Power Controls Glossary

The maximum current, in amperes, that a conductor or device can carry continuously without exceeding its temperature rating.

The amount of current that could flow during a short circuit at a specific point in the electrical system.

A rigid copper or aluminum conductor used to distribute power inside switchboards, panelboards, and other electrical assemblies.

Series 16 devices are the standard for temporary power tie-ins, rated by ampacity and keyed by color to enforce correct phase and ground connection.

A color-coded, single-pole separable connector used for temporary generator or load bank connections.

An overcurrent protective device that opens a circuit automatically during overload or short-circuit conditions.

An enclosure containing electrical controls, relays, PLCs, terminals, and related components used to operate equipment or systems.

Busbar made from copper, typically selected for high conductivity, thermal performance, and compact current-carrying capacity.

Equipment construction where energized parts are not exposed on the operating face. UL 891 is the standard commonly associated with dead-front switchboards. (UL Solutions)

A generator docking station configured for both temporary generator connection and load bank testing.

The cabinet or housing that protects electrical components from personnel contact, weather, dust, and installation conditions.

A circuit that carries power from service equipment or switchgear to downstream panelboards, transformers, or distribution equipment.

Zinc-iron coated steel that improves corrosion resistance and provides a paint-ready surface for powder-coated enclosures.

A conductive path connected to earth or equipment grounding conductors to help clear faults and stabilize system voltage.

A busbar used to terminate equipment grounding conductors inside electrical equipment.

An unintended current path between an energized conductor and ground or grounded equipment.

A grounding method that separates sensitive equipment grounding paths from general equipment grounding noise.

A trapped-key interlock system used to enforce a safe operating sequence between breakers, switches, or power sources.

A device that applies an electrical load to a generator so it can be tested under controlled operating conditions.

A docking station used to connect a portable load bank to a generator or electrical system for testing.

The primary overcurrent protective device controlling power into a switchboard, panelboard, or service entrance assembly.

Equipment supplied without a main breaker, where incoming conductors terminate directly on main lugs.

A physical device that prevents two switches or breakers from being closed at the same time.

An indoor enclosure rating intended to provide protection against incidental contact with enclosed equipment.

An indoor or outdoor enclosure rating that provides protection against access to hazardous parts and a degree of protection from falling rain, sleet, snow, and external ice. (NEMA)

An outdoor enclosure type similar to 3R but with added corrosion resistance.

A busbar used to terminate neutral conductors in an electrical assembly.

The NFPA standard covering performance requirements for emergency and standby power systems that provide alternate electrical power in buildings. (NFPA)

Protection against excessive current caused by overloads, short circuits, or faults.

A wall-mounted or cabinet-mounted distribution assembly containing buses and overcurrent devices for branch or feeder circuits. UL states that UL 67 is the basic standard used to investigate panelboards. (UL Solutions)

The sequence of phases in a three-phase electrical system. Incorrect phase rotation can cause motors to run backward.

A device that verifies proper phase sequence before equipment is energized or transferred.

A durable baked-on finish applied to metal enclosures for appearance and corrosion resistance.

Equipment that distributes incoming power to multiple downstream loads, often with breakers, metering, and branch circuit protection.

Short Circuit Current Rating. The maximum short-circuit current equipment can withstand without creating a shock or fire hazard under specified conditions.

Equipment suitable for use at the point where utility power enters a facility, including required disconnecting and bonding provisions.

A device that limits transient voltage spikes by diverting surge energy away from protected equipment.

A component that limits transient voltage spikes by diverting excess energy away from connected equipment. Integrated into power distribution equipment, an SPD helps protect downstream loads from surges caused by switching events, lightning, or generator transfer.

A large electrical distribution assembly used to divide incoming power into branch or feeder circuits. UL 891 is commonly used for dead-front switchboards. (UL Solutions)

A permanent connection point that allows a portable generator to be connected during outages, maintenance, or emergency operation.

Equipment that transfers electrical load between normal and alternate power sources.

The UL standard for industrial control panels.

The UL standard for panelboards. It covers panelboards used for lighting, appliance branch circuits, and power circuits. (UL Solutions)

The UL standard commonly used for dead-front switchboards. UL describes UL 891 as broadly recognized and applied in North America. (UL Solutions)

A mechanical interlock using a pivoting beam so only one of two breakers can be closed at a time.

The level of fault current equipment can tolerate for a defined period without failure.