Electrical Terms Electrical Definitions
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Solar Cells
POWERandDATA.info_Solar-Cell Foil-1.1
Solar Cell Foil
POWER can be generated by a solar cell (photovoltaic cell). Photovoltaic comes from the words photo, which means light, and voltaic, which means volt (a component of electrical power). An absorber is one of several thin layers of different materials in a photovoltaic cell assembly that make it possible for it to generate power.

It should be noted that a photovoltaic cell does not generate electrical power by converting photons (light particles) into something else. Instead, it uses the energy that photons provide to free existing electrons from their connected state. After that the photon's work is done and the freed electrons and photovoltaic cell assembly do the rest. For more see diagram in the view below.

  » Also see How Solar Cells Work, Wikipedia: Solar cell, and Encyclopeadia Britanica: Absorber Layer.
ACAlternating Current
Nanofabricated Accelerator

DATA processing (computing) speed drives the computer world. Humans hunger for it and businesses depend on it. Software and hardware accelerators are used to help increase data processing speed.

POWERandDATA.info_ Accelerator-Data-2

The biggest difference between hardware and software is that hardware has much more of an ability to perform multiple tasks at the same time or concurrently. Generally speaking, hardware that performs acceleration and is a separate unit (card) from the CPU is referred to as a hardware accelerator, but is more commonly referred to its specific use (such as a graphics accelerator).

Software accelerators increase speed by making software applications run more efficiently. Executing software code is when a computer reads code and then makes it do what it's written to do. That takes computing time. One type of software accelerator increases computing speed by decreasing computing time. A way of doing that is by bypassing/not executing code in an application that is not necessary for what the user is trying to accomplish.

For more go to Wikipedia: Accelerator.

accessible (as applied to equipment)[CEC 2010] Admitting close approach; not guarded by locked doors, elevation, or other effective means.
accessible (as applied to wiring methods)[CEC 2010] Capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building.
accessible, readily (readily accessible)[CEC 2010] Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth.
accuracyIn general accuracy is the comparison of an indicated or published value from original tests to a value referenced in a more recent test report. Mathematically it is usually shown as the extent to which a reference measurement agrees with the indicated value for that measurement. Here is an example comparing an indicated valued based on factory testing with factory instruments (indicated value) to a referenced value based on field testing with field instruments (referenced value). If published sound data indicates the sound pressure level of a particular model generator at seven meters is 100 decibels (indicated value), but field sound test reports references only 90 decibels at the same distance (referenced value), then the indicated value is 90% accurate. Purchases are usually made based on indicated values. To make sure you got what you paid for, reference values of generators, UPSs, and data related equipment should always be checked against indicated values after installation and startup.
A/D converterA device that converts an analog signal such as generator output voltage into a digital “word” for use by a microprocessor in order to print readable data, show on a control panel, computer, or remote enunciator, or broadcast text messages.
aeration (of coolant)The entrainment of gas into an engines coolant. Cause gas (air and/or combustion gas) to join and circulate with engine coolant. A process used by some engines that drive generators.
adjustable (as applied to circuit breakers)[CEC 2010] A qualifying term indicating that the circuit breaker can be set to trip at various values of current, time, or both, within a predetermined range. Instantaneous Trip (as applied to circuit breakers ). A qualifying term indicating that no delay is purposely introduced in the tripping action of the circuit breaker.
aftercoolingProcess by which an engines combustion chargeair exiting from the final stage of compression is cooled by means of an air to air, or liquid to air, heat exchanger, before re-introduction into the engine. A process used by some engines that drive generators.
air bleedPressurized air in a gas turbine engine compressor allowed to escape. A process used by some engines that drive generators.
air cleanerDevice to filter combustion air at the entrance to the combustion air circuit. Air cleaners are used on some engines that drive generators.
air cooled engineAn engine that is cooled by means of air being forced about the heated parts of the engine. A method used by some engines that drive generators.
air/fuel ratioAir/fuel ratio = mass of delivered air / mass of delivered fuel. Engines that drive generators run most efficiently when they get the proper air/fuel ratio.
air gapA separating space between two parts of magnetic material through which the magnetic flux must pass. A typical representation of this space is the clearance between the rotor and stator of an electrical generator.
air/gas startingUsing compressed air or gas to crank engine or turbine. A process sometimes use by engines that drive generators.
air intake silencerDevice to reduce the noise of incoming combustion air and objectionable noise originating in the air intake manifold. Air intake silencers are used on some engines that drive generators.
air restrict indicatorA device used to measure air flow at an air cleaner. It's purpose is to detect restricted air flow and then signal that maintenance of the air cleaner (filter) is required. Air restrict indicators are included in some generator engine monitors. Also see failure prediction.
alternating current (AC)The varying, direction changing flow of electric charge. Alternating current reverses in regularly recurring intervals of time, has alternately positive and negative values, and occurs a specified number of times per second. These changes are measured in cycles per second, which are called Hertz.
alternatorA device that converts mechanical energy into electrical energy (power) with alternating current . It is also referred to as an AC generator or synchronous generator.
alternator (for charging batteries) An engine driven AC generator, usually self regulating, and self rectifying, which provides DC power for the purposes of re-charging the battery(s) used for starting the engine and providing power to engine controls and monitoring systems. These alternators usually have an output rating of about 1 to 3 kW at either 12 volts or 24 volts.
altitudeThe vertical elevation relative to sea level at which a generator is operating.
altitude ratingThe maximum generator power output rating indicated at a given altitude.
ambient temperatureTemperature of the air that surrounds the generating and related equipment. The ambient temperature for optimum performance rating may vary from device to device.
American Bureau of Shipping (ABS)A marine classification and inspection association that establishes various requirements for shipbuilding and equipment for use on ships.
American Wire Gauge (AWG)Standard solid copper wire sizes used in the United States. It is the same as the Brown & Sharp gauge.
ampacity[CEC 2010] The current, in amperes , that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. For more go to Wikipedia: ampacity.
Illustration of a Moving Coil Ammeter.
Hand held ammeter. Sometimes referred to as a Current Clamp or Clamp Meter.
An instrument used to measure electric current. Electric current is measured in amperes, thus the name ammeter. There are six basic types of ammeters:

  1. Moving-coil ammeter
  2. Electrodynamic ammeter
  3. Moving-iron ammeter
  1. Hot-wire ammeter
  2. Digital ammeter
  3. Integrating ammeter

Also see recording ammeter.  
ampereThe base SI unit of electrical current, equivalent to one coulomb per second, formally defined to be the constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per meter of length. Abbreviation: A, amp. Also see ampacity . For more go to Wikipedia: ampere and Dictionary.com: ampere.
amper frame (AF)The full current carrying capacity of a circuit breaker or the maximum current that the breaker can carry before tripping.
ampere trip (AT)The amount of current a circuit breaker is set to trip at in an overcurrent or short circuit condition.
appliance[CEC 2010] Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, and so forth.
approved[CEC 2010] Acceptable to the authority having jurisdiction.
askarel[CEC 2010] Generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. Under arcing conditions, the gases produced, while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible gases, depending on the askarel type.

[Also referred to as Polychlorinated biphenyl or PCB, askarel was used mostly as insulation in transformers. Due to PCBs' environmental toxicity and classification as a persistent organic pollutant, PCB production was banned by the United States Congress in 1979 and by the Stockholm Convention on Persistent Organic Pollutants in 2001.] For more go to. Wikipedia: Polychlorinated biphenyl and Dictionary.com: askarel.
attachment plug (plug cap) (plug)[CEC 2010] A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.
authority having jurisdiction (AHJ)[CEC 2010] An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure.

FPN: The phrase "authority having jurisdiction", or its acronym AHJ, is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances, the property owner or his or her designated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction.
automatic[CEC 2010] Self-acting, operating by its own mechanism when actuated by some impersonal influence, as, for example, a change in current, pressure, temperature, or mechanical configuration.
automatic transfer switch (ATS)>>> This definition is still being prepared. Please check back later. Thanks
AWGAmerican Wire Gauge(AWG)
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bathroom[CEC 2010] An area including a basin with one or more of the following: a toilet, a tub, or a shower.
bonded (bonding)[CEC 2010] Connected to establish electrical continuity and conductivity.
For more go to: Wikipedia: electrical bonding.
bonding jumper[CEC 2010] A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.
bonding jumper, equipment[CEC 2010] The connection between two or more portions of the equipment grounding conductor. Bonding Jumper, Main. The connection between the grounded circuit conductor and the equipment grounding conductor at the service.
branch circuit[CEC 2010] The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).
Also see branch circuit, appliance , branch circuit, general-purpose , branch circuit, individual, branch circuit, multiwire , and branch circuit, overcurrent device .
branch circuit, appliance[CEC 2010] A branch circuit that supplies energy to one or more outlets to which appliances are to be connected and that has no permanently connected luminaries that are not a part of an appliance.
branch circuit, general-purpose[CEC 2010] A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.
branch circuit, individual[CEC 2010] A branch circuit that supplies only one utilization equipment.
branch circuit, multiwire[CEC 2010] A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
branch circuit, overcurrent device[CEC 2010] A device capable of providing protection for service, feeder, and branch circuits and equipment over the full range of overcurrents between its rated current and its interrupting rating. Branch-circuit overcurrent protection devices are provided with interrupting ratings appropriate for the intended use but no less than 5,000 amperes.
branch circuit, overcurrent protection deviceSame as overcurrent protection device (OPD)
building[CEC 2010] A structure that stands alone or that is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.
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cabinet[CEC 2010] An enclosure that is designed for either surface mounting or flush mounting and is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.
California Building Code (CBC)California Building Code is part of the California Building Standards Code (CBSC) and is maintained by the California Building Standards Commission. It consists of two volumns. Vol-1 includes Chapters 1 thru 15 and Vol-2 includes Chapter 16 thru 35. Both volumes include the full table of contents, appendix, and index. See link to both volumes under California Building Standards Code (Parts) 2013 below.
    » For a list of links to all of California's building codes see California Building Standards Code (Parts) below.
California Building Standards Code (CBSC)The California Building Standards Code regulates building design and construction in the State of California, USA. The CBSC is established by Title 24 of the California Code of Regulations (CCR). It's maintained by the California Building Standards Commission and is published by the International Code Council (ICC) who also wrote it.  Also see International Building Code (IBC) and International Code Council (ICC) below.
    » For a list of links to all of California's building codes see California Building Standards Code (Parts) below.
California Building Standards Code (Parts) 20132013 California Building Standards Code is made up of the following parts: NOTES:
  1. Downloading- CBC Vol-1 and Vol-2 can be quickly downloaded here. All other codes can be downloaded at there respective links above.
  2. Next Code Cycle- Unless stated otherwise by the State of California, as of January 1, 2017 these (2013) codes will be superceded by the 2016 codes.
California Building Standards Code (Parts) 20102010 California Building Standards Code is made up of the following parts: NOTES:
  1. As of January 1, 2014 these (2010) codes will be superceded by the 2013 codes.
  2. The above codes can be downloaded in PDF format here.
California Electrical Code (CEC)This document is the 3rd of 12 Parts of the official triennial compilation and publication of the adoptions, amendments and repeal of administrative regulations to California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This Part is known as the California Electrical Code [CEC] and incorporates, by adoption, the previous edition of the National Electrical Code (NEC) of the National Fire Protection Association (NFPA) with the California amendments.

Note: The probability of major seismic events (earthquakes) in the State of California, US, is among the highest in the world. Because of this as well as for environmental reasons the State of California amends the National Electrical Code (NEC) to its higher requirements and standards making it one of the most stringent codes in the world. It's for this reason that we normally reference the California Electric Code (CEC) in lieu of the National Electrical Code (NEC) and the electrical section of the International Building Code (IBC). To view an easy to navigate version in a new tab click here . To open a PDF version in a new tab (9 MB) click here .
CEC 20102010 edition of the California Electrical Code. To view an easy to navigate version in a new tab click here . To open a PDF version in a new tab (9 MB) click here . Also see California Electrical Code (CEC) above.
circuitIn simple terms a circuit is pathway made of conductors in which electrical electrical current travels. In a bit more complex terms a circuit is a network of conductors consisting of a closed loop, giving a return path for the electrical current. For electrical engineering purposes circuits are broken down into two major parts: 1) Feeder circuits (sometimes referred to as feeders) and 2) branch circuits .
For more go to Wikipedia: Electrical network.
circuit breaker[CEC 2010] A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.

FPN: automatic opening means can be integral, direct acting with the circuit breaker, or remote from the circuit breaker.
For more go to Wikipedia: Circuit breaker.
circuit breaker [Over 600V][CEC 2010] [Over 600V] A switching device capable of making, carrying, and interrupting currents under normal circuit conditions, and also of making, carrying for a specified time, and interrupting currents under specified abnormal circuit conditions, such as those of short circuit.
clothes closet[CEC 2010] A non-habitable room or space intended primarily for storage of garments and apparel.
code precedence When the code of a governing authority overrides (can by law be enforced over) the code of another governing authority. Some examples would be when City code is enforcable over State code or Federal code is enforcable over State code.

As a rule of thumb the more restrictive or stringent code takes precedence over the lesser code. Because that could be up for interpretation, the higher governing authority normally determines which code will govern or take precedence over the other.

The State of California is a perfect example of that. The preface of the California Building Code (CBC) states "A city, county or city and county may establish more restrictive building standards reasonably necessary because of local climatic, geological or topographical conditions. Findings of the local condition(s) and the adopted local building standard(s) must be filed with the California Building Standards Commission to become effective and may not be effective sooner than the effective date of this edition of California Building Standards Code. Local building standards that were adopted and applicable to previous editions of the California Building Standards Code do not apply to this edition without appropriate adoption and the required filing." This means that unless a city within the limits of the State of California prepares its own code based on the CBC, files it with the State, and adopts it, all construction within the city limits will be subject to and governed by the California Building Standards Code (CBSC).

It should also be noted that as of 2000 most building codes in the United States are based on the International Building Code (IBC), which is a model only and has no jurisdictional power. The California Building Standards Code (CBSC) is made up of the IBC and added restrictions.  See International Building Code (IBC) and International Code Counsil (ICC) below.
communications equipment[CEC 2010] The electronic equipment that performs the telecommunications operations for the transmission of audio, video, and data, and includes power equipment (e.g., dc converters, inverters, and batteries) and technical support equipment (e.g., computers).
concealed[CEC 2010] Rendered inaccessible by the structure or finish of the building. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them.
conductTo carry electric current.
conductionThe carrying of electrical current from one point to another. Conduction is limited by the material the conductivity, conductance and resistivity, resistance.
conductivity, conductanceElectrical conductivity or specific conductance is the opposite of electrical resistivity and represents a material's ability to a class="glink" href="#conduct"> conduct electric current.
For more go to Wikipedia: Electrical resistivity and conductivity .
conductorIn physics and electrical engineering, a conductor is an object or type of material which permits the flow of electric charges in one or more directions. For example, a wire is an electrical conductor that can carry electricity along its length.
For more go to: Wikipedia: conductor Also ref. conductor, bare, conductor, covered, and conductor, insulated.
For more go to Wikipedia: Electrical conductor.
conductor fillA category in the [CEC 2010] index under which is referenced just about everything that could house and give a protected pathway for California Electrical Code (CEC 2010), scroll down to the bottom of the table of content and click on the Index link, then scroll down to Conductive fill.
conductor, bare[CEC 2010] A conductor having no covering or electrical insulation whatsoever.
conductor, covered[CEC 2010] A conductor encased within material of composition or thickness that is not recognized by this Code as electrical insulation.
conductor, insulated[CEC 2010] A conductor encased within material of composition and thickness that is recognized by this Code as electrical insulation.
conduitTubing used for carrying and protecting electrical conductors (wiring) between electrical devices . There are several materials that governing codes allow conduit to be made of. The most common are metal and plastic. The use of any type of conduit is limited by governing codes .
For more go to Wikipedia: Electrical conduit . Also see conductor fill .
conduit body[CEC 2010] A separate portion of a conduit or tubing system that provides access through a removable cover(s) to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system. Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bodies.
connector, pressure (solderless)[CEC 2010] A device that establishes a connection between two or more conductors or between one or more conductors and a terminal by means of mechanical pressure and without the use of solder.
continuous load[CEC 2010] A load where the maximum current is expected to continue for 3 hours or more.

P&D Comment-1: Continuous load is often referred to as Long Continuous Load or LCL.
P&D Comment-2: It's important to understand continuous load because CEC 210.20A and NEC 210.20A both state that "Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load."

Why is this required? Brian Spaziani of Advanced Electrical Training explains. "What you'll notice when reading the sections on continuous loads is that they are directly related to the overcurrent protection devices and/or assemblies [such as circuit breakers and panels]. That's because the equipment rating is the exact reason we're doing it. They're derated or listed to operate at 80% of their rating continuously. This is even clearer when taking a look at the exceptions.

For overcurrent devices and conductors you're permitted to calculate continuous loads at 100% when the assemblies and overcurrent devices are listed to operate at 100% of their rating.

For conductors the more obvious exception is for grounded conductors (neutrals). When they don't terminate on an overcurrent device they aren't required to be calculated at 125%.

In case you didn't know, taking the load at 125% is the same as 80% of the device rating. 1.25 and 0.8 are reciprocals.

For example: A 120 volt 20 amp circuit rating is 2,400 VA (120 x 20). 80% of 2,400 VA is 1,920 VA (2400 x 0.8). Now if you take the 1,920 VA at 125% or times 1.25 you'll get 2,400 VA." For more go to: Advanced Electrical Training: Continuous Loads | 125% Decoded.
controlled vented power fuse[CEC 2010] [Over 600V] A fuse with provision for controlling discharge circuit interruption such that no solid material may be exhausted into the surrounding atmosphere.

FPN: The fuse is designed so that discharged gases will not ignite or damage insulation in the path of the discharge or propagate a flashover to or between grounded members or conduction members in the path of the discharge where the distance between the vent and such insulation or conduction members conforms to manufacturer's recommendations.
controller[CEC 2010] A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.
cooking unit, counter-mounted[CEC 2010] A cooking appliance designed for mounting in or on a counter and consisting of one or more heating elements, internal wiring, and built-in or mountable controls.
coordination (selective)[CEC 2010] Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the choice of overcurrent protective devices and their ratings or settings, [OSHPD 1, 2, 3, & 4] utilizing the 0.10 second level of the overcurrent protective device [OPD] from the time current curve as the basis for the lower limit of the calculation method.
copper-clad aluminum conductors[CEC 2010] Conductors drawn from a copper-clad aluminum rod with the copper metallurgically bonded to an aluminum core. The copper forms a minimum of 10 percent of the cross-sectional area of a solid conductor or each strand of a stranded conductor.
cost reductionThe best way to explain cost reduction analysis is to compare it to value engineering analysis. There is one fundamental difference. Value engineering analysis includes some post-construction operating expenses and cost reduction does not. So what are they and how are they calculated? Let's take a look. . . For more see POWER & DATA article, Value Engineering, by Greg Kulda
coulombThe charge transported by a steady current of one ampere in one second.
For more go to: Wikipedia: coulomb.
criticalFor our purposes "critical" means something that human life, information security, or business profits is dependent upon.
critical dataData that human life, information security, or business profits is dependent upon.
critical powerPower that human life, information security, or business profits is dependent upon.
Alien Crosstalk
Crosstalk (XT) is when a signal transmitted on one circuit or channel of a transmission system creates an undesired effect on another circuit or channel. In structured communications and signal cabling, crosstalk can refer to electromagnetic interference from one unshielded twisted pair to another twisted pair, normally running in parallel. Crosstalk is measured as follows.

  • Near End Crosstalk (NEXT). NEXT is a measure of the ability of cabling to reject crosstalk. Interference between two pairs in a cable measured at the same end of the cable as the interfering transmitter. Crosstalk is undesirable. In crosstalk, the signals traveling through adjacent pairs of wire in twisted-pair cabling interfere with each other. The pair causing the interference is called the “disturbing pair,” while the pair experiencing the interference is the “disturbed pair.” Channel NEXT is the NEXT value measured between one wire pair and another in the same cable; NEXT is measured at both ends of the wire. The NEXT value for a given cable type is generally expressed in decibels per feet or decibels per 1000 feet. NEXT value varies with the frequency of transmission. The higher the NEXT value, the greater the cable’s ability to reject crosstalk at its local connection. Generally specifications for cabling (such as CAT 5) include the minimum NEXT values.

  • Power Sum Near End Crosstalk (PSNEXT). A NEXT measurement which includes the sum of crosstalk contributions of all adjacent pairs.

  • Far End Crosstalk (FEXT). Interference between two pairs of a cable measured at the other end of the cable with respect to the interfering transmitter.

  • Equal Level Far End Crosstalk (ELFEXT). An FEXT measurement with attenuation compensation.

  • Alien Crosstalk (AXT). Interference caused by other cables routed close to the cable of interest.
currentAn electric current is a flow of electric charge. Electric charge flows when there is voltage present across a conductor. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in a plasma. The SI unit for measuring an electric current is the ampere , which is the flow of electric charges through a surface at the rate of one coulomb per second. Electric current can be measured using an ammeter. Electric currents cause many effects, notably heating, but also induce magnetic fields, which are widely used for motors , inductors , and generators . For more go to Wikipedia: Electric current.
cutout[CEC 2010] [Over 600V] An assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link) or may act as the disconnecting blade by the inclusion of a nonfusible member.
cutout box[CEC 2010] An enclosure designed for surface mounting that has swinging doors or covers secured directly to and telescoping with the walls of the box proper.
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dataAs it relates to power & data, data means data centers. It includes the structure that houses them, their layout, data storage systems, frames (racks) that support them, air conditioning systems, power systems, and back-up power systems and everything else about them.

Data are values of qualitative or quantitative variables, belonging to a set of items. Data in computing (or data processing) are represented in a structure, often tabular (represented by rows and columns), a tree (a set of nodes with parent-children relationship) or a graph structure (a set of interconnected nodes). Data are typically the results of measurements and can be visualized using graphs or images. However, in today's world of computer hard drives and servers, just about any information stored/listed in a computer database is considered data (such as this list of power and data terminology and definitions.

Breaking down the term 'data', as an abstract concept it can be viewed as the lowest level of abstraction from which information and then knowledge are derived. Raw data, i.e., unprocessed data, refers to a collection of numbers, characters and is a relative term; data processing commonly occurs by stages, and the "processed data" from one stage may be considered the "raw data" of the next. Field data refers to raw data collected in an uncontrolled environment. Experimental data refers to data generated within the context of a scientific investigation by observation and recording.

As for it's origin, the word 'data' is the plural of datum, neuter past participle of the Latin dare, "to give", hence "something given". In discussions of problems in geometry, mathematics, engineering, and so on, the terms given and data are used interchangeably. Such usage is the origin of data as a concept in computer science or data processing: data are numbers, words, images, etc., accepted as they are. Click here for more on 'Data'.
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DCDirect Current
dead front[CEC 2010] Without live parts exposed to a person on the operating side of the equipment.
demand factor[CEC 2010] The ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration.
device[CEC 2010] A unit [or component] of an electrical system that carries or controls electric energy as its principal function.
direct current (DC)The non-varying, unidirectional flow of electric charge. Direct current flows in a constant direction, distinguishing it from alternating current (AC).
disconnectA device by which conductors can be temporarily broken and the flow of electrical current from the power source is stopped. There are three basic types; manual disconnect and fused disconnect and combo disconnect. For more on each type, click on the green links.
disconnect, combo (manual/fused) A manual disconnect that is also fused. The fuse is inline so that the conductor can be broken by either operation. Combo disconnects are use when overcurrent protection in addition to upstream circuit breakers is desired.
disconnect, fusedA fused disconnect that operates with a fuse instead of a hinged metal bar like manual disconnects. Also see disconnecting means.
disconnect, manualManual disconnects are mechanical in nature. Basic models consist of a hinged metal bar that is attached to the downstream conductor . When in the connected position the hinged metal bar fits tightly between two fixed, but flexible pieces of metal that are attached to the upstream conductor coming from the power source. When the hinged bar is manually rotating it disengages from in-between the two flexible metal pieces breaking the flow of electrical current. Also see disconnecting means.
disconnecting (or isolating) switch (disconnector, isolator)[CEC 2010] [Over 600V] A mechanical switching device used for isolating a circuit or equipment from a source of power.
disconnecting means[CEC 2010] [Over 600V] A device, group of devices, or other means whereby the conductors of a circuit can be disconnected from their source of supply.
disconnecting means (over 600V)[CEC 2010] A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
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dusttight[CEC 2010] Constructed so that dust will not enter the enclosing case under specified test conditions.
duty, continuous[CEC 2010] Operation at a substantially constant load for an indefinitely long time.
duty, intermittent[CEC 2010] Operation for alternate intervals of (1) load and no load; or (2) load and rest; or (3) load, no load, and rest.
duty, periodic[CEC 2010] Intermittent operation in which the load conditions are regularly recurrent.
duty, short-time[CEC 2010] Operation at a substantially constant load for a short and definite, specified time.
duty, varying[CEC 2010] Operation at loads, and for intervals of time, both of which may be subject to wide variation.
dwelling unit[CEC 2010] A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation.
dwelling, multifamily[CEC 2010] A building that contains three or more dwelling units.
dwelling, one-family[CEC 2010] A building that consists solely of one dwelling unit.
dwelling, two-family[CEC 2010] A building that consists solely of two dwelling units.
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EGC[CEC 2010] Equipment Grounding Conductor (Grounding Conductor, Equipment).
electric powerSame as electrical power".
electric power production and distribution network[CEC 2010] Power Production, distribution, and utilization equipment and facilities, such as electric utility systems that deliver electric power to the connected loads, that are external to and not controlled by an interactive system.
electric sign[CEC 2010] A fixed, stationary, or portable self- contained, electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention.
electrical energy>>> We apologize! This definition is still being prepared. Please check back later. Thanks
electrical powerThe rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Electric power is usually produced by electric generators, but can also be supplied by chemical sources such as electric batteries. Electric power is generally supplied to businesses and homes by the electric power industry. Electric power is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours.
For more go to Wikipedia: Electrical power.
electromagnetIn its most basic form an electromagnet is a piece of iron that becomes magnetized while inside the magnetic field of a solenoid. The momentous benefit to that is that when the solenoid stops making the magnetic field the iron stops being a magnet and to stop the solenoid from making a magnetic field, you simply turn off the electrical current.

Why is that so momentous, you say! Well, did you know that electromagnets are what make motors work. That's why when you turn them on (send electric current to them) they start running. The different types of mechanisms that use motors to operate are countless. Items like fans, washing machines, and the starter in your car all operate with motors built out of electromagnets.

Because of their ability to turn on and off at the flip off a switch, electromagnets revolutionized the world and drove the industrial age.

Electromagnets are widely used in electrical devices other than motors as well. They include electrical generators, relays, automatic transfer switches, loudspeakers, computer hard disks, MRI machines, scientific instruments, magnetic separation equipment, and industrial lifting electromagnets for picking up and moving heavy iron objects like scrap iron just to name a few.

   » For more go to Wikipedia: Electromagnet.
electronically actuated fuse[CEC 2010] [Over 600V] An overcurrent protective device [OPD] that generally consists of a control module that provides current sensing, electronically derived time-current characteristics, energy to initiate tripping, and an interrupting module that interrupts current when an overcurrent occurs. Electronically actuated fuses may or may not operate in a current-limiting fashion, depending on the type of control selected.
enclosed[CEC 2010] Surrounded by a case, housing, fence, or wall(s) that prevents persons from accidentally contacting energized parts.
enclosure[CEC 2010] The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts or to protect the equipment from physical damage.

FPN: See Table 110.20 for examples of enclosure types.
energized[CEC 2010] Electrically connected to, or is, a source of voltage.
energy (electric)Go to Wikipedia: Electric energy .
equipment[CEC 2010] A general term, including material, fittings, devices, appliances, luminaries, apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.
explosion proof apparatus[CEC 2010] Apparatus enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited thereby.

FPN: For further information, see ANSI/UL 1203-1999, Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations.
exposed (as applied to live parts)[CEC 2010] Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to part that are not suitably guarded, isolated, or insulated.
exposed (as applied to wiring methods)[CEC 2010] On or attached to the surface or behind panels designed to allow access.
expulsion fuse unit (expulsion fuse)[CEC 2010] [Over 600V] A vented fuse unit in which the expulsion effect of gases produced by the arc and lining of the fuseholder, either alone or aided by a spring, extinguishes the arc. Nonvented Power Fuse. A fuse without intentional provision for the escape of arc gases, liquids, or solid particles to the atmosphere during circuit interruption.
externally operable[CEC 2010] Capable of being operated without exposing the operator to contact with live parts.
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failure prediction>>> This definition is still being prepared. Please check back later. Thanks.
feederSame as feeder circuit.
feeder circuit[CEC 2010] All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.
festoon lighting[CEC 2010] A string of outdoor lights that is suspended between two points.
fine print notes (FPN)[CEC 2010] Notes that are used in the California Electrical Code (CEC), are informational only, and are not enforceable as requirements of the Code.
fitting[CEC 2010] An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.
FPNAcronym for Fine Print Notes. FPNs are used in the California Electrical Code (CEC) to clarify code language. CEC 2010 refers to them as "Explanatory material, such as references to other standards, references to related sections of this Code, or information related to a Code rule". They are informational only, and are not enforceable as requirements of the Code. Ref. CEC 2010 (clicking will open a PDF version of CEC 2010 in a new tab).
fuse[CEC 2010] [Over 600V] An overcurrent protection device [OPD] with a circuit-opening fusible part that is heated and severed by the passage of overcurrent through it.

FPN: A fuse comprises all the parts that form a unit capable of performing the prescribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit.
For more go to Wikipedia: Fuse.
fused disconnect>>> This definition is still being prepared. Please check back later. Thanks
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garage[CEC 2010] A building or portion of a building in which one or more self-propelled vehicles can be kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes.

FPN: For commercial garages, repair and storage, see Article 511.
>>> This definition is still being prepared. Please check back later. Thanks   
generator enclosureGenerator enclosures are shields that protect outside generators from weather, animals, vehicles, and unauthorized personnel. There are two types: primary and secondary.

Primary. The primary enclosure is made of metal, is integral to the generator set, and is purchased from the generator manufacturer as an accessory. It can be ordered with sound insulation to reduce noise.
POWERandDATA.info: Generator Enclosure Made of Block
This enclosure sheilds a 350kW genset that includes a primary enclosure. Also see Views below.
Photos courtesy of: Tony Nuzzo, Shore Break Electric

Secondary. The secondary enclosure is a fence that surrounds the generator area and associated components within it (such as a standalone fuel tank, electrical disconnect, spill kits, etc.), and is built by a contractor. If appearance and sound are not a concern, chain link fencing is often used to keep costs down. If it need to look good or blend in, concrete block is usually used. The height of a block enclosure wall is determined by the size of the generator and required sound attenuation, but as a rule of thumb run about 3 feet above the top of the generator or primary enclosure. The enclosure can be made as attractive as the surrounding architecture calls for as long as applicable codes are met.

Governing Codes . Spaces (clearances) around electrical equipment, including generators, are dictated by CEC 110.26. No smoking signage is called for in CFC 2703.7.1. Because of the fuel stored within the enclosure for use by the generator, hazardous material warning signs are required in accordance with CFC 2703.5 and NFPA 704. Also reference CFC 407.3. Fire extinguishers are required in accordance with CFC 906 and CFC 3403.2.1. If concrete block is used to construct the enclosure, CBC 2101.2 and CBC 2101.3 require a structural engineer's calculations and stamped construction drawings. If a roof is designed over the enclosure other building codes will apply and some engineering may be required.
generator fuel tank codesMany of the codes and standards that apply to fuel storage tanks are not found in standard building codes and are often hard to find if you don't know where to look. For that reason we assembled them in a separate page called Regulations. It contains a lot of information like this page does so it might take a few seconds to load.

generator fuel polishingFuel Polishing is the removal of water, sediment, non-combustible particulate matter and microbial contamination below levels stated in ASTM D975 (Standard Specification for Diesel Fuel Oils) while resuspending combustible particulate matter to maintain ASTM standards for BTU value, lubricity, and cetane (measurement of the combustion quality of diesel fuel during compression ignition).

Fuel polishing uses centrifuges, coalescers, and filters to remove non-combustible particulate matter (sand, dust, cigarette wrappers, lady bugs, and anything else that makes its way into the tank) from fuel. In other words, everything that wasn’t really supposed to be there in the first place.

Because water is heavier than fuel, the centrifuges and coalescers that. Then water blocking filters to pick up the last little bit of suspended or “entrained” water.

The primary difference between fuel polishing and fuel filtration is that fuel polishing acknowledges that fuel itself can degrade and cause solids. Fuel filters will simply pull the solids out because they plug up filters whereas fuel polishers break down the combustible solids so that the fuel stays within the industry specifications.

Because, the solids that fuel – particularly diesel, kerosene, home heating oil, and some of the JP (jet propulsion) fuel, creates are exactly the aspects of fuel that add lubricity and BTU value to it. If you cycle the fuel through filters over and over again you will remove all of those solids and through the fuel out of spec! It simply won’t have the power or lubricity that your diesel engine will require!

It's important to note that If you have a Tier-1, Tier-2, Tier-3, or Tier-4 engine (highly engineered to reduce emissions), then it is going to be VERY finicky about the fuel it consumes. If there is some sort of failure, catastrophic or not, and the manufacturer discovers that the fuel is out of spec, then there is a strong possibility that they will void the warrantee!

If the fuel has been standing for an exceptionally long time it might be wise to have the inside of the tank cleaned aat the same time There are quite a few services that do both.
GFCIGround-Fault Circuit Interrupter (GFCI)
governing codes>>> This definition is still being prepared. Please check back later. Thanks
ground[CEC 2010] The earth.
grounded (grounding)[CEC 2010] Connected (connecting) to ground or to a conductive body that extends the ground connection.
grounded conductor[CEC 2010] A system or circuit conductor that is intentionally grounded.
grounded, solidly[CEC 2010] Connected to ground without inserting any resistor or impedance device.
ground-fault circuit interrupter (GFCI)[CEC 2010] A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.

FPN: Class A ground-fault circuit interrupters trip when the current to ground is 6 mA or higher and do not trip when the current to ground is less than 4 mA. For further information, see UL 943, Standard for Ground-Fault Circuit Interrupters.
ground-fault protection of equipment[CEC 2010] A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device.
grounding conductor[CEC 2010] A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
grounding conductor, equipment (EGC)[CEC 2010] The conductive path installed to connect normally non?current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

FPN: No. 1: It is recognized that the equipment grounding conductor also performs bonding.

FPN: No. 2: See 250. 118 for a list of acceptable equipment grounding conductors.
grounding electrode[CEC 2010] A conducting object through which a direct connection to earth is established.
grounding electrode conductor[CEC 2010] A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.
guarded[CEC 2010] Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach or contact by persons or objects to a point of danger.
guest room[CEC 2010] An accommodation combining living, sleeping, sanitary, and storage facilities within a compartment.
guest suite[CEC 2010] An accommodation with two or more contiguous rooms comprising a compartment, with or without doors between such rooms, that provides living, sleeping, sanitary, and storage facilities.
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handhole enclosure[CEC 2010] An enclosure for use in underground systems, provided with an open or closed bottom, and sized to allow personnel to reach into, but not enter, for the purpose of installing, operating, or maintaining equipment or wiring or both.
hoistway[CEC 2010] Any shaftway, hatchway, well hole, or other vertical opening or space in which an elevator or dumbwaiter is designed to operate.
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identified (as applied to equipment)[CEC 2010] Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code requirement.

FPN: Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation.
inductor >>> This definition is still being prepared. Please check back later. Thanks
in sight from (within sight from, within sight)[CEC 2010] Where this Code specifies that one equipment shall be ?in sight from,? ?within sight from,? or ?within sight of,? and so forth, another equipment, the specified equipment is to be visible and not more than 15 m (50ft) distant from the other.
interactive system[CEC 2010] An electric power production system that is operating in parallel with and capable of delivering energy to an electric primary source supply system.
International Building Code (IBC)Code officials around the world recognized the need for a modern, up-to-date building code addressing the design and installation of building systems through requirements emphasizing performance so they formed the International Code Council (ICC). In 2000 they published the first International Building Code, which replaced the old Uniform Building Code (UBC). It's designed to meet these needs through model code regulations that safeguard the public health and safety in all communities, large and small. It's also an effort to standardize building codes worldwide or as they put it in the preface on Page iii, "it encourages international consistency in the application of its provisions".

The word model is emphasized to point out that the code is not Federal law and does not take precedence over State laws. Instead, States adopt the IBC model as their law. In many cases States adapt the IBC to their siesmic, geographic, and climate conditions first, usually making it stricter, and then adopt it. That is what the State of California does.

Also see code precedence.
International Code Council (ICC)An association dedicated to developing model codes and standards used in the design, build, and compliance process to construct safe, sustainable, affordable, and resilient structures in all areas of the world. Most U.S. communities and many global communities have adopted the International Codes or are based on them.

For more go to International Code Council (ICC).  Also see International Building Code (IBC) and code precedence above.
interrupter switch[[CEC 2010] [Over 600V] A switch capable of making, carrying, and interrupting specified currents.
interrupting rating[CEC 2010] The highest current at rated voltage that a device is intended to interrupt under standard test conditions.

FPN: Equipment intended to interrupt current at other than fault levels may have its interrupting rating implied in other ratings, such as horsepower or locked rotor current. Intersystem Bonding Termination. A device that provides a means for connecting communications system(s) grounding conductor(s) and bonding conductor(s) at the service equipment or at the disconnecting means for buildings or structures supplied by a feeder or branch circuit.
inverse time (as applied to circuit breakers)[CEC 2010] A qualifying term indicating that there is purposely introduced a delay in the tripping action of the , which delay decreases as the magnitude of the current increases.
isolated (as applied to location)[CEC 2010] Not readily accessible to persons unless special means for access are used.
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kitchen[CEC 2010] An area with a sink and permanent facilities for food preparation and cooking.
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labeled[CEC 2010] Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
lamp (electrical component)Referred to in electrical codes as a luminaire ., a lamp is a replaceable component such as a light bulb, which is designed to produce light from electricity. In electrical terms a lamp is not an assembly that sits on a desk or table, which in electrical terms is a lampholder. Nor is it an assembly that is mounted to a wall or ceiling, which in electrical terms is a light fixture. A lamp is usually made up of a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. Re-lamping is the replacement of only the removable lamp in a light fixture.
LCL Long Continuous Load .
lighting outlet[CEC 2010] An outlet intended for the direct connection of a lampholder or luminaries .
listed[CEC 2010] Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.

FPN: The means for identifying listed equipment may vary for each organization concerned with product evaluation, some of which do not recognize equipment as listed unless it is also labeled. Use of the system employed by the listing organization allows the authority having jurisdiction to identify a listed product.
live parts[CEC 2010] Energized conductive components.
loadIn simple terms, load or electrical load is the power demand put on a circuit. If measured in amps an example would be a toaster and a blender plugged into an outlet. If the each require 10 amps of current to operate, then when both are turned on they put a total load of 20 amps on the circuit. When calculating the size of an electrical panel, all potential loads are included in the calculation to come up with a total potential load. Also see load study below.
load studyThe collection of load data on an active panel over a specified period of time and then using the data in calculations to establish the maximum demand on it. There are two methods of collecting load data:

1) Tabulation
The tabulation method determines potential load or potential load plus existing load by summing the load of all electrical appliances, equipment, lighting, etc. that might be connected and applying factors in accordance with CEC Article 220.1 - 220.86. Note that CEC Article 220 doesn't specifically define this method. It only implies it.

2) Ammeter Recording.
Current (amps) recorded over a period of time. There are two periods of time allowed by CEC Article 220.87 and one by California's Office of Statewide Health Planning and Development (OSHPD). They are as follows:
  • One Year: CEC Article 220.87.1. states "The maximum demand data is available for a 1-year period." This data would come from the utility company that provided the electricity to the facility. It's best if it's provided in maximum 15 minute increments.

  • 30 Day: CEC Article 220.87.1 also states "Exception: If the maximum demand data for a 1-year period is not available, the calculated load shall be permitted to be based on the maximum demand (measure of average power demand over a 15-minute period) continuously recorded over a minimum 30-day period using a recording ammeter or power meter connected to the highest loaded phase of the feeder or service, based on the initial loading at the start of the recording. The recording shall reflect the maximum demand of the feeder or service by being taken when the building or space is occupied and shall include by measurement or calculation the larger of the heating or cooling equipment load, and other loads that may be periodic in nature due to seasonal or similar conditions."

  • Three Day (72 hour): OSHPD's PIN 38 allows you to determine maximum demand (measure of average power demand over a 15-minute period) with continuous recording over a minimum 72 hour period using a recording ammeter.
location, damp[CEC 2010] Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.
location, dry[CEC 2010] A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.
location, wet[CEC 2010] Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.
long continuous loadSame as continuous load . Acronym: LCL
luminaire[CEC 2010] A complete lighting unit consisting of a light source such as a lamp or lamps, together with the parts designed to position the light source and connect it to the power supply. It may also include parts to protect the light source or the ballast or to distribute the light. A lampholder [such as a light fixture or table lamp] itself is not a luminaire. [a light bulb is a luminaire]
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manual transfer switch (MTS)
POWERandDATA.info: Generator Enclosure Made of Block
Drafting Symbol
A transfer switch that is operated manually. A manual transfer switch can be used instead of an automatic transfer switch (ATS). In some situations the use of a manual transfer switch is more practical. A good example can be seen in the Single Line Diagram view below where a manual transfer switch is used to switch between a permanent standby generator and a temporary generator. Before ATS's were developed all transfer switches were manually operated. An ATS should also have a built-in manual transfer switch that overrides the ATS so it can be maintained and repaired.

As seen in the Inner Mechanics view below, manual transfer switches are very mechanical in nature. Basic models consist of a hinged metal bar that is attached to the load conductor. When in the connected position the hinged metal bar fits tightly between two fixed, but flexible pieces of metal that are attached to a power source conductor. When the hinged bar is manually rotated (switched) from one side to the other it disengages from in-between the two flexible metal pieces and engages the same on the other side that is connected to a different power source conductor.
metal-enclosed power switchgear[CEC 2010] A switchgear assembly completely enclosed on all sides and top with sheet metal (except for ventilating openings and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with buses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided by doors, removable covers, or both. Metal-enclosed power switchgear is available in non-arc-resistant or arc-resistant constructions.
motorAn electric motor is a machine that uses electricity to turn a shaft that then turns something else (such as a fan, pump, household appliance, power tool, machine tool, and disk drive). It does that by converting electrical energy into mechanical energy. In normal motoring mode, most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force within the motor that causes a shaft to turn. In certain applications, such as in the transportation industry with traction motors, electric motors can operate in both motoring and generating or braking modes to also produce electrical energy from mechanical energy.
For more go to Wikipedia: Electric motor.
motor control center[CEC 2010] An assembly of one or more enclosed sections having a common power bus and principally containing motor control units.
multioutlet assembly[CEC 2010] A type of surface, flush, or freestanding raceway designed to hold conductors and receptacles, assembled in the field or at the factory.
multiple fuse[CEC 2010] [Over 600V] An assembly of two or more single-pole fuses.
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National Electrical Code (NEC)The National Electrical Code (NEC) (clicking will open a new tab) is developed and maintaned by the National Fire Protection Association. For this reason the National Electrical Code is also referenced as NFPA 70. It is adopted in all 50 states.
National Fire Protection Association (NFPA) National Fire Protection Association (clicking will open a new tab). The NFPA developes and maintains the National Electrical Code (NEC).
NEC National Electrical Code .
neutral conductor[CEC 2010] The conductor connected to the neutral point of an system that is intended to carry current under normal conditions.
neutral point[CEC 2010] The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system.

FPN: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential.
NFPA National Fire Protection Association
NFPA Codes & StandardsThe NFPA prepares and publishes over 350 different codes and standards. The most notable ones are the National Fire Code (NFC) and the National Electric Code (NEC). The rest address specialized items (such as the Flammable and Combustible Liquids Code). A complete list with links can be found here.

It should be noted that not all of the codes listed apply to construction related activities. However, in California, most of the ones that do can be found in the California Fire Code (CFC). Also see code precedence and California Building Standards Code (Parts) 2010.
nonadjustable (as applied to circuit breakers)[CEC 2010] A qualifying term indicating that the circuit breaker does not have any adjustment to alter the value of current at which it will trip or the time required for its operation.
nonautomatic[CEC 2010] Action requiring personal intervention for its control. As applied to an electric controller, nonautomatic control does not necessarily imply a manual controller, but only that personal intervention is necessary. Nonlinear Load. A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.

FPN: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.
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Office of Statewide Health and Planning Development (OSHPD) >>> This definition is still being prepared. Please check back later. Thanks.
oil cutout (oil-filled cutout)[CEC 2010] [Over 600V] A cutout in which all or part of the fuse support and its fuse link or disconnecting blade is mounted in oil with complete immersion of the contacts and the fusible portion of the conducting element (fuse link) so that are interruption by severing of the fuse link or by opening of the contacts will occur under oil.
oil switch[CEC 2010] [Over 600V] A switch having contacts that operate under oil (or askarel or other suitable liquid).
OPD Overcurrent Protection Device
OSHPD >>> This definition is still being prepared. Please check back later. Thanks.
outageTerm used to describe the loss of electrical power from the utility service (electric company) to a facility or residence. Facilities and residences that have a standby generator get power back quickly when an automatic transfer switch (ATS) senses that electrical power from the utility service has been lost and switches to power from the standby generator. The ATS also tells the standby generator to turn on.
outlet[CEC 2010] A point on the wiring system at which current is taken to supply utilization equipment.
outline lighting[CEC 2010] An arrangement of incandescent lamps, electric-discharge lighting, or other electrically powered light sources to outline or call attention to certain features such as the shape of a building or the decoration of a window.
over 600VWhereas most California Electric Code (CEC) definitions are intended to apply wherever the terms are used throughout the Code, the definitions with this notation are applicable only to parts of the CEC specifically covering installations and equipment operating at over 600 volts, nominal.
overcurrent[CEC 2010] Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault.

FPN: A current in excess of rating may be accommodated by certain equipment and conductors for a given set of conditions. Therefore, the rules for overcurrent protection are specific for particular situations.
For more go to Wikipedia: Overcurrent.
overcurrent deviceSame as an overcurrent protection device (OPD). A device that stops the flow of overcurrent (such as a circuit breaker , fuse, or disconnect). Also see branch circuit overcurrent device .
overcurrent protection device (OPD)A device that stops the flow of overcurrent (such as a circuit breaker , fuse or disconnect ).
overload[CEC 2010] Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.
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panelboard[CEC 2010] A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall, partition, or other support; and accessible only from the front.
For more go to Wikipedia: Distribution board.
plenum[CEC 2010] A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
plugA device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle. Also see attachment plug (plug cap) (plug)
powerGeneraly speaking in reference to energy, the term "power" is internationally understood to mean electricity or electrical power.
POWERandDATA.info Animated-P&D-XXXL
Power & Data means the special relationship and dependency that exists between critical power and critical data. It also means. . . More »
power fuse unit[CEC 2010] [Over 600V] A vented, nonvented, or controlled vented fuse unit in which the arc is extinguished by being drawn through solid material, granular material, or liquid, either alone or aided by a spring.
power outlet[CEC 2010] An enclosed assembly that may include receptacles, circuit breakers, fuseholders, fused switches, buses, and watt-hour meter mounting means; intended to supply and control power to mobile homes, recreational vehicles, park trailers, or boats or to serve as a means for distributing power required to operate mobile or temporarily installed equipment.
power source >>> This definition is still being prepared. Please check back later. Thanks.
premises wiring (system)[CEC 2010] Interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all their associated hardware, fittings, and wiring devices, both permanently and temporarily installed. This includes (a) wiring from the service point or power source to the outlets or(b) wiring from and including the power source to the outlets where there is no service point. Such wiring does not include wiring internal to appliances, luminaries , motors, controllers, motor control centers, and similar equipment.
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qualified person[CEC 2010] One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.

FPN: Refer to NFPA 70E?-2004, Standard for Electrical Safety in the Workplace, for electrical safety training requirements.
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raceway[CEC 2010] An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
Also see conductor fill.
rainproof[CEC 2010] Constructed, protected, or treated so as to prevent rain from interfering with the successful operation of the apparatus under specified test conditions.
raintight[CEC 2010] Constructed or protected so that exposure to a beating rain will not result in the entrance of water under specified test conditions.
receptacle[CEC 2010] A receptacle is a contact device installed at the outlet for the connection of an attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is two or more contact devices on the same yoke.
receptacle outlet[CEC 2010] An outlet where one or more receptacle are installed.
recording ammeter>>> This definition is still being prepared. Please check back later. Thanks
regulator bypass switch[CEC 2010] [Over 600V] A specific device or combination of devices designed to bypass a regulator.
remote-control circuit[CEC 2010] Any electrical circuit that controls any other circuit through a relay or an equivalent device.
resistivity, resistanceElectrical resistivity or specific resistance is the opposite of electrical conductivity and represents how much a material limits the conduction of electric current.
For more go to Wikipedia: Electrical resistivity and conductivity .
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sealable equipment[CEC 2010] Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made accessible without opening the enclosure. The equipment may or may not be operable without opening the enclosure.
separately derived system[CEC 2010] A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.
service[CEC 2010] The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.
service cable[CEC 2010] Service conductors made up in the form of a cable.
service conductors[CEC 2010] The conductors from the service point to the service disconnecting means.
service disconnectA disconnect that breaks the flow of electrical current through a service conductors.
service disconnect overcurrent deviceSame as a fused disconnect.
service drop[CEC 2010] The overhead service conductors from the last pole or other aerial support to and including the splices, if any, connecting to the service-entrance conductors at the building or other structure.
service equipment[CEC 2010] The necessary equipment, usually consisting of a circuit breaker(s) or switch(es) and fuse(s) and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of the supply.
service lateral[CEC 2010] The underground service conductors between the street main, including any risers at a pole or other structure or from transformers, and the first point of connection to the service-entrance conductors in a terminal box or meter or other enclosure, inside or outside the building wall. Where there is no terminal box, meter, or other enclosure, the point of connection is considered to be the point of entrance of the service conductors into the building.
service point[CEC 2010] The point of connection between the facilities of the serving utility and the premises wiring.
service-entrance conductors, overhead system[CEC 2010] The service conductorsbetween the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the service drop.
service-entrance conductors, underground system[CEC 2010] The service conductors between the terminals of the service equipment and the point of connection to the service lateral.

FPN: Where service equipment is located outside the building walls, there may be no service-entrance conductors or they may be entirely outside the building.
setting (of circuit breakers)[CEC 2010] The value of current , time, or both, at which an adjustable circuit breakers is set to trip.
short circuitAn abnormal connection between two conductors of an electric circuit intended to be at different voltages. This results in an overcurrent with little resistance from the rest of the circuit potentially causing circuit damage, overheating, fire, or explosion.
For more go to Wikipedia: Short circuit.
short-circuit current rating[CEC 2010] The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.
show window[CEC 2010] Any window used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level.
SIAn abbreviation of the French term Le Systeme international d'unites, which means The International System of Units. As it relates to electricity, SI represents a unit of electrical current equivalent to one coulomb per second.
For more go to: ampacity , Wikipedia: ampere, and Dictionary.com: ampere.
signaling circuit[CEC 2010] Any electrical circuit that energizes signaling equipment.
solar photovoltaic system[CEC 2010] The total components and subsystems that, in combination, convert solar energy into electric energy suitable for connection to a utilization load.
solenoidIn its most basic form, a solenoid is a coil of wire that produces a magnetic field in a volume of space when an electric current is passed through it. It does not matter which direction the electric current runs in order for a solenoid to produce a magnetic field. For this reason Direct Current (DC) or Alternating Current (AC) can be used. A solenoid is the key component to making an electromagnet.
special permission[CEC 2010] The written consent of the authority having jurisdiction.
standby generator >>> This definition is still being prepared. Please check back later. Thanks.
structure[CEC 2010] That which is built or constructed.
supplementary overcurrent protective device[CEC 2010] A device intended to provide limited overcurrent protection for specific applications and utilization equipment such as luminaries and appliances. This limited protection is in addition to the protection provided in the required branch circuit by the branch circuit overcurrent protective device [OPD] .
surge arrester[CEC 2010] A protective device for limiting surge voltages by discharging or bypassing surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions.
surge-protective device (SPD)[CEC 2010] A protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions and is designated as follows:
  • Type 1: Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device
  • Type 2: Permanently connected SPDs intended for installation on the load side of the service disconnect overcurrent device , including SPDs located at the branch panel.
  • Type 3: Point of utilization SPDs.
  • Type 4: Component SPDs, including discrete components, as well as assemblies.
FPN: For further information on Type 1, Type 2, Type 3, and Type 4 SPDs, see UL 1449. Standard for Surge Protective Devices.
switch, bypass isolation[CEC 2010] A manually operated device used in conjunction with a transfer switch to provide a means of directly connecting load conductors to a power source and of disconnecting the transfer switch.
switch, general-use[CEC 2010] A switch intended for use in general distribution and branch circuits. It is rated in amperes, and it is capable of interrupting its rated current at its rated voltage.
switch, general-use snap[CEC 2010] A form of general-use switch constructed so that it can be installed in device boxes or on box covers, or otherwise used in conjunction with wiring systems recognized by this Code.
switch, isolating[CEC 2010] A switch intended for isolating an electrical circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means.
switch, motor-circuit[CEC 2010] A switch rated in horsepower that is capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.
switch, transfer[CEC 2010] An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another.
switchboard[CEC 2010] A large single panel, frame, or assembly of panels on which are mounted on the face, back, or both, switches, overcurrent and other protective devices, buses, and usually instruments. Switchboards are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets. Thermally Protected (as applied to motors). The words Thermally Protected appearing on the nameplate of a motor or motorcompressor indicate that the motor is provided with a thermal protector.
For more go to Wikipedia: Electrical switchboard.
switching device[CEC 2010] [Over 600V] A device designed to close, open, or both, one or more electrical circuits.
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thermal protector (as applied to motors)[CEC 2010] A protective device for assembly as an integral part of a motor or motor-compressor that, when properly applied, protects the motor against dangerous overheating due to overload and failure to start.

FPN: The thermal protector may consist of one or more sensing elements integral with the motor or motor-compressor and an external control device.
transfer switch
POWERandDATA.info: Generator Enclosure Made of Block
Drafting Symbol
A device that switches the source of electrical power. There are two basic types:
    • Manual Transfer Switch (MTS)
    • Automatic Transfer Switch (ATS)

Uses & Capabilities. Transfer switches are most commonly used to switch power from utility power to standby generator power. Automatic ransfer switches should be capable of both automatic switching and manual switching with automatic being the primary operation and manual being the backup operation.

As can be seen in the following View, the mechanics of a manual transfer switch can be very simple. However, with the advancement of technology, automatic transfer switches have become faster, more reliable, and do more.
    » For more on each type of transfer switch, click on the green links above. VIEW:  TRANSFER SWITCH- Inner Mechanics
twisted pair
Communication Cable-1-POWERandDATA.info
Unshielded Twisted Pairs
Communication Cable-2-POWERandDATA.info
Shielded Twisted Pairs
Twisted pair cabling is a low voltage wire assembly used specifically for sending communication signals between devices (such as telephones, computers, alarms, and electronic instruments). It's made up of two small gauge conductors that are twisted together. Simply twisting them together cancels out most noise that would otherwise be picked up from other wires next to them. Noise is the term used to describe electromagnetic interference (EMI) from external sources (such as electromagnetic radiation from other unshielded twisted pair (UTP) cables) and crosstalk between neighboring pairs. The twisted pair was invented by Alexander Graham Bell. In order to know which type of twisted pair cabling to use you should know a bit about the following:

  • Twist Rate: The twist rate (also called pitch of the twist, usually defined in twists per meter), adds a second level of protection. If pairs with the same twist rates lie next to each other some EMI and crosstalk will likely occure. For this reason the twist rates should differ and are usually specified accordingly.

  • Shielding: Twisted pair cables are often shielded in an attempt to prevent electromagnetic interference from outside the cable. Shielding provides an electric conductive barrier to attenuate electromagnetic waves external to the shield. Shielding can be applied to individual pairs or quads, or to the collection of pairs. Individual pairs are foiled, while overall cable may use an thin braided wire screen, foil, or both braiding and foil.

  • Wire Codes: The code before the slash designates the shielding for the cable itself, while the code after the slash determines the shielding for the individual pairs or sets of wires. See legend below.
Code Chart
TP=Twisted Pair
TQ=Twisted pair, individual shielding in Quads
F=Foil Shielding
S=Braided Shielding (outer layer only)

   » For more go to Wikipedia: Twisted pair.
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ungrounded[CEC 2010] Not connected to ground or to a conductive body that extends the ground connection.
upstream >>> This definition is still being prepared. Please check back later. Thanks
utility >>> This definition is still being prepared. Please check back later. Thanks.
utility-interactive inverter[CEC 2010] An inverter intended for use in parallel with an electric utility to supply common loads that may deliver power to the utility.
utilization equipment.[CEC 2010] Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.
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value engineeringThe best way to explain value engineering analysis is to compare it to cost reduction analysis. There is one fundamental difference. Value engineering analysis includes some post-construction operating expenses and cost reduction does not. So what are they and how are they calculated? Let's take a look. . . For more see POWER & DATA article, Value Engineering, by Greg Kulda
vented power fuse[CEC 2010] [Over 600V] A fuse with provision for the escape of are gases, liquids, or solid particles to the surrounding atmosphere during circuit interruption.
ventilated[CEC 2010] Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors.
volatile flammable liquid[CEC 2010] A flammable liquid having a flash point below 38° C (100° F), or a flammable liquid whose temperature is above its flash point, or a Class II combustible liquid that has a vapor pressure not exceeding 276 kPa (40 psia) at 38° C (100° F) and whose temperature is above its flash point.
voltageThe electric potential difference between two points, or the difference in electric potential energy of a unit charge transported between two points.
For more go to Wikipedia: Voltage .
voltage (of a circuit)[CEC 2010] The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned.

FPN: Some systems, such as 3-phase 4-wire, single-phase 3-wire, and 3-wire direct current, may have various circuits of various voltages.
voltage to ground[CEC 2010] For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
voltage, nominal[CEC 2010] A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.

FPN: See ANSI C84.1-2006, Voltage Ratings for Electric Power Systems and Equipment (60 Hz).
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watertight[CEC 2010] Constructed so that moisture will not enter the enclosure under specified test conditions.
weatherproof[CEC 2010] Constructed or protected so that exposure to the weather will not interfere with successful operation.

FPN: Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor.
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<< Y >> A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
y!Something thinkers often ponder. Thanks for letting us humor you a bit!
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I think Eric Schmidt , executive chairman of Google, in his 2009 University of Pennsylvania Commencement Address, put it best when he said "None of us is as smart as all of us." There are so many of you around the world with great power & data knowledge. The challenge we've been having is getting our hands on it. We believe the community based approach to this website will make that much easier for everyone. Power & Data.info-Head wCircuit

We have found power and data information resources on the internet to be limited. Don't get us wrong, Google found us some information, but we just found it difficult and very time consuming at times to find everything we needed. On top of that we were never able to find a single source or even a few sources on the web that could be relied on to quickly get a lot of power and data information for commercial and industrial purposes. Human resources with power and data knowledge either don't have the time to explain things, don't have the ability to explain things, or they want a lot of money to do it. In this economy, that's difficult to afford.

Speed learning is often crucial. Whether it's an engineer designing, a contractor building, a professor teaching, or a student learning, readily available information will increase their success. One of our goals is to make power and data information much faster to find.

Demand is growing. The need for data storage and data servers is growing at an unbelievable rate. To keep up, data storage and server technology is changing rapidly as well. There are now thousands upon thousands of hard working, fast moving people who design and construct the data centers that house the technology and the standby/emergency/back-up power systems that prevent down time and lost data. Those people need a way to find power and data information, be alerted of changes, and kept informed.

Power & Data.info-CA003.1-Think-1 Trans OBJECTIVES?
Eric Schmidt also said in his Commencement Address that "Success is really about being ready for the good opportunities that come before you." There are several objectives that we intend to achieve. 1.) Develop a source of power and data information that can be accessed quickly so you can be ready for the next opportunity when it comes. 2.) Have a platform for healthy debate in an effort to clarify power and data information. 3.) Have a platform to standardize power and data terminology, power and data communication styles (written, drafted, and spoken), and power and data means and methods.

Well, we want to make it fun and stimulating so here's what we are doing:
  • Building Databases :   We will continually add to the databases in Power & Data's Knowledge Center (such as Terminology, Design & Engineering, Downloads, News, and other categories as needed). We intend to also provide information via blogs regularly. To make it easier to keep up, if you choose to subscribe, you will automatically be notified when new information and publications are posted.

  • Your Comments: A In the comments section under the posts, we ask and challenge you to comment, add-to, criticize, compliment, clarify, etc. That way everyone can learn from you. Try to write clear and concise explanations, and please keep it professional.
    Mind Gears Turning-1
    Are your gears turning?

  • Your Contributions: A Using the Contact Us page we urge you to send us articles you've written, articles you recommend, topics you would like us to touch on, news, terms and definitions, unique and/or challenging designs and engineering, and even your ideas on how to improve the Power & Data Knowledge Center.

  • Your Brain: A Ok, we admit it. We like your brain. Just by the fact that you are reading this means it's powerful; there is a lot of valuable knowledge in it that could help others be successful. We would like to extract a copy of what you know and input it here for the world to find and benefit from. Hope you don't mind!
My career in the building industry (Greg's bio) has been wonderful and includes many successes. Those successes however were in large part a result of many very kind people sharing their design and construction knowledge with me. Of those I prospered most from the ones that enjoyed healthy debate, sometimes over the smallest of issues, in an effort to think everything through to the fullest with the intent of getting the job done right the first time. One of the things I really liked about that process is that everyone involved benefited, which included sleeping better at night.
Mind Dump
Mind Dump

Those are the famous words of my good friend and colleague Ray Juncosa, Vise President at Heery International. Of all the great professionals I've had the pleasure of working with he definitely is the best at trading information. We worked out numerous, sometimes project threatening, issues on massive medical center projects by talking through and often debating them - sometimes for hours. Our sessions almost always started with an outpouring of information Ray would call a "mind dump". Once that was done there was no turning back. It started the gears turning, adrenalin flowed to the brain, and mental synergy kicked into overdrive! That is what we want to happen through this website.
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