Power Distribution Terms

Power distribution terms related to Specialty Lighting products.

amperage, ampere, amp (A)

Amperage (A) is the volume (or quantity) of electrical current flowing through a circuit.  For example, volume is measured in amperes, otherwise referred to as amps (A).


A complete path for electrical current flowing from the building power source to the equipment being powered and back to the power source. Also, circuits are rated according to the number of amps (A) they can accommodate.

circuit breaker

A safety device designed to automatically stop the flow of electricity whenever a circuit becomes overloaded, i.e., exceeds the number of amps (A) that the wiring can accommodate.

electrical rating

The rating of an electrical appliance or device that indicates the voltage (V) at which the appliance is designed to work and the current consumption at that voltage (V).

electrical switch

A device used to interrupt the flow of electrons in a circuit.  Also, switches are essentially binary devices: they are either completely on (closed) or completely off (open).

grounded plug

A male three-prong plug (two flat blades and one round prong) with the third round prong on the plug being the ground connector.  It is round and just under the two blade-style plug protrusions.  Therefore, the ground prong acts as an emergency path for electricity to travel through if a short circuit or other fault develops inside the electrical device.  Also, it can be called a polarized plug.

grounded receptacle

A female outlet (receptacle) with a third wire called a ground wire is called a grounded receptacle, or outlet, and will have three slots. A ground wire is an important safety feature, because if a electrical system, or an individual outlet, get a surge of excess electricity, a grounded receptacle reduces the risk of fire, shock, or electrocution.

hertz (Hz)

Hertz (Hz) is the unit of frequency measurement, and with respect to electric power is the measure of number of electric cycles of an alternating current (AC) occurring per unit time (one second).

High-Definition Multimedia Interface (HDMI)

A proprietary (trademark) audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device.

hospital grade receptacle

In addition to complying with the general use requirements, hospital grade receptacles are specially designed and are subject to additional requirements of the standards.  For example, these include additional grounding reliability, assembly integrity, strength and durability.

IP rating (Ingress Protection)

A rating that defines levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc.) and moisture.

junction box

A box containing a junction of electric wires or cables and provides protection and a safety barrier for electrical connections.


Describes the amount of power (amps) consumed by an electrical circuit or device.  Loads are usually expressed in amps (A), but sometimes in watts (W).


An electrical socket located on a power distribution unit (PDU).

non-grounded outlet or receptacle

An outlet or receptacle that has only two wires, and has no ground wire.  Also, called an ungrounded, outlet or ungrounded receptacle.

non-grounded plug

A male plug with only two prongs and no ground prong. Also, can called a ungrounded plug.


A female receptacle for the male plug of an electrical device.

National Electrical Code (NEC)

Approved by the American National Standards Institute (ANSI), the NEC is the most complete set of electrical Code requirements that govern electrical installations in the interest of safety for persons and property.

ohm (Ω)

Ohm is the measure of electrical resistance, or impedance, in a circuit. For example, one volt (V) will cause one amp (A) to flow through one ohm of resistance.


A male fitting for making an electrical connection to a live circuit by insertion into a female receptacle or connector.

polarized plug

See grounded plug.

power distribution unit (PDU)

A device fitted with multiple outlets designed to distribute and manage electric power.


A female electrical outlet or plug into which the male plug or connector of an electrical device may be inserted.

surge suppressor

A device that protects electronic equipment from damage in the event of a power surge or voltage spike.  Also, it is referred to as a surge protector.

tamper-resistant (TR)

Tamper-resistant receptacles contain a built-in shutter system that allows plugs to be inserted when equal pressure is applied simultaneously to both sides of the receptacle. Therefore, when a plug is inserted into the receptacle, both springs are compressed and the shutters then open, allowing the metal prongs to make contact to create an electrical circuit.  The purpose of TR receptacles is to reduce the risk of electrical injuries.  Note:  They are not completely tamper-proof.

UL Listed, cUL, CSA, ETL

UL Listed refers to electrical/mechanical equipment or materials tested and listed under the standards of Underwriters’ Laboratories, Inc (UL), a private laboratory.  The symbol identifies listed products.  cUL is the Canadian equivalent of UL; the cUL symbol is also marked on products listed for use in Canada.  A CSA mark appears on products tested by the Canadian Standards Association.  Finally, the ETL listing mark appears on products tested by Electrical Test Laboratories, Inc., which is a lab equivalent to UL.

USB charging receptacle (Universal Serial Bus)

A receptacle used to charge a smartphone or other portable device using a USB charging cord.

voltage, volts (V)

The measure of electrical pressure in a circuit expressed in volts (V).  For example, one volt of pressure is required to push one amp (A) of current through a conductor with one ohm of resistance.

wattage, watts (W)

The amount of power used by an electrical device. To calculate wattage (W), multiply voltage (V) and amperage (A). Watts (W) can be converted to amps (A) with this calculation. For example,  watts (W) divided by volts (V) equals amps (A).

wire gauge

The diameter (thickness) of a wire, that one measures in numbers.   This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight.  Generally, the smaller the gauge number, the thicker the cable.


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