This comprehensive guide provides clear and detailed definitions of essential electrical engineering terms, ensuring accuracy and ease of understanding. From branch circuits and busbars to building systems and broadband, each term is explained with precision, including relevant references and informational notes.
Whether you’re a professional or a student, this resource is designed to help you navigate complex electrical concepts with confidence.
1. Bathroom
An area including a sink with one or more of the following: a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fixtures.
(CMP—2)
2. Battery
A single cell or a group of cells connected together electrically in series, in parallel, or a combination of both.
(CMP—13)
3. Flow Battery
An energy storage component that stores its active materials in the form of one or two electrolytes external to the reactor interface. When in use, the electrolytes are transferred between the reactor and storage tanks.
(706) (CMP—13)
Informational Note: Three commercially available flow battery technologies are zinc-air, zinc-bromine, and vanadium redox, sometimes referred to as pumped electrolyte ESS.
4. Sealed Battery
A battery that has no provision for the routine addition of water or electrolyte or for external measurement of electrolyte specific gravity and might contain pressure relief venting.
(CMP—13)
5. Stationary Standby Battery
A battery that spends the majority of the time on continuous float charge or in a high state of charge, in readiness for a discharge event.
(CMP—13)
Informational Note: Uninterruptible Power Supply (UPS) batteries are an example that falls under this definition.
6. Battery-Powered Lighting Units
Individual unit equipment for backup illumination consisting of a rechargeable battery; a battery-charging means; provisions for one or more lamps mounted on the equipment, or with terminals for remote lamps, or both; and a relaying device arranged to energize the lamps automatically upon failure of the supply to the unit equipment.
(517) (CMP—15)
7. Berth
The water space to be occupied by a boat or other vessel alongside or between bulkheads, piers, piles, fixed and floating docks, or any similar access structure.
(555) (CMP—7)
Informational Note: See the definition of Slip for additional information.
8. Bipolar Circuit
A DC circuit that is comprised of two monopole circuits, each having an opposite polarity connected to a common reference point.
(CMP—4)
9. Block
A square or portion of a city, town, or village enclosed by streets and including the alleys so enclosed, but not any street.
(800) (CMP—16)
10. Boatyard
A facility used for constructing, repairing, servicing, hauling from the water, storing (on land and in water), and launching of boats.
(555) (CMP—7)
11. Artificially Made Bodies of Water
Bodies of water that have been constructed or modified to fit some decorative or commercial purpose such as, but not limited to, aeration ponds, fish farm ponds, storm retention basins, treatment ponds, and irrigation (channel) facilities. Water depths may vary seasonally or be controlled.
(682) (CMP—17)
12. Natural Bodies of Water
Bodies of water such as lakes, streams, ponds, rivers, and other naturally occurring bodies of water, which may vary in depth throughout the year.
(682) (CMP—17)
13. Bonded (Bonding)
Connected to establish electrical continuity and conductivity.
(CMP—5)
14. Bonding Conductor (Bonding Jumper)
A conductor that ensures the required electrical conductivity between metal parts that are required to be electrically connected.
(CMP—5)
15. Equipment Bonding Jumper
The connection between two or more portions of the equipment grounding conductor.
(CMP—5)
16. Main Bonding Jumper
The connection between the grounded circuit conductor and the equipment grounding conductor, or the supply-side bonding jumper, or both, at the service.
(CMP—5)
17. Supply-Side Bonding Jumper
A conductor installed on the supply side of a service or within a service equipment enclosure(s), or for a separately derived system, that ensures the required electrical conductivity between metal parts required to be electrically connected.
(CMP—5)
18. System Bonding Jumper
The connection between the grounded circuit conductor and the supply-side bonding jumper, or the equipment grounding conductor, or both, at a separately derived system.
(CMP—5)
19. Border Light
A permanently installed overhead strip light.
(520) (CMP—15)
20. Bottom Shield
A protective layer installed between the floor and flat conductor cable (Type FCC) to protect the cable from physical damage. It may or may not be incorporated as an integral part of the cable.
(324) (CMP—6)
21. Branch Circuit (Branch-Circuit)
The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).
(CMP—2)
22. Appliance Branch Circuit
A branch circuit that supplies energy to one or more outlets to which appliances are connected and has no permanently connected luminaires that are not part of an appliance.
(CMP—2)
23. General-Purpose Branch Circuit
A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.
(CMP—2)
24. Individual Branch Circuit
A branch circuit that supplies only one utilization equipment.
(CMP—2)
25. Motor Branch Circuit
The circuit conductors, including equipment, between the motor branch-circuit short-circuit and ground-fault protective device and an individual motor.
(CMP—11)
26. Multiwire Branch Circuit
A branch circuit consisting of two or more ungrounded conductors with a voltage between them and a neutral conductor with equal voltage between it and each ungrounded conductor, connected to the system’s neutral conductor.
(CMP—2)
27. Branch-Circuit Selection Current (BCSC)
The value in amperes used instead of the rated-load current to determine the ratings of motor branch-circuit conductors, disconnecting means, controllers, and branch-circuit short-circuit and ground-fault protective devices. This value is equal to or greater than the marked rated-load current.
(440) (CMP—11)
28. Breakout Assembly
An adapter used to connect a multipole connector containing two or more branch circuits to multiple individual branch-circuit connectors.
(520) (CMP—15)
29. Broadband
Wide bandwidth data transmission that transports multiple signals, protocols, and traffic types over various media types.
(CMP—16)
30. Building
A structure that stands alone or is separated from adjoining structures by fire walls.
(CMP—1)
31. Floating Building
A building that floats on water, is moored in a permanent location, and has a premises wiring system served through connection by permanent wiring to an electrical supply system not located on the premises.
(CMP—7)
32. Manufactured Building
Any building of closed construction made or assembled in manufacturing facilities on or off the building site for installation or assembly and installation on the building site, excluding manufactured homes, mobile homes, park trailers, or recreational vehicles.
(545) (CMP—7)
33. Building Component
Any subsystem, subassembly, or other system designed for use in or as part of a structure, including structural, electrical, mechanical, plumbing, and fire protection systems, and other systems affecting health and safety.
(545) (CMP—7)
34. Building System
Plans, specifications, and documentation for a system of manufactured building or for a type or system of building components, including structural, electrical, mechanical, plumbing, and fire protection systems, and other systems affecting health and safety. Variations permitted by regulation are included as part of the building system.
(545) (CMP—7)
35. Bulkhead
A vertical structural wall, usually of stone, timber, metal, concrete, or synthetic material, constructed along and generally parallel to the shoreline to retain earth and provide suitable water depth at the waterside face.
(555) (CMP—7)
36. Bull Switch
An externally operated wall-mounted safety switch that may contain overcurrent protection and is designed for the connection of portable cables and cords.
(530) (CMP—15)
37. Bundled
Cables or conductors that are tied, wrapped, taped, or otherwise periodically bound together.
(520) (CMP—15)
38. Busbar
A noninsulated conductor electrically connected to the source of supply and physically supported on an insulator, providing a power rail for connection to utilization equipment such as sensors, actuators, A/V devices, low-voltage luminaire assemblies, and similar electrical equipment.
(393) (CMP—18)
39. Busbar Support
An insulator that runs the length of a section of suspended ceiling bus rail, supporting and isolating the busbars from the suspended grid rail.
(393) (CMP—18)
40. Busway
A raceway consisting of a metal enclosure containing factory-mounted, bare or insulated conductors, usually copper or aluminum bars, rods, or tubes.
(CMP—8)
Summary Table
| Term | Definition | Reference |
|---|---|---|
| Bathroom | Area with a sink and plumbing fixtures (toilet, tub, etc.). | CMP—2 |
| Battery | Single or grouped cells connected in series, parallel, or both. | CMP—13 |
| Flow Battery | Energy storage with external electrolytes transferred during use. | 706, CMP—13 |
| Sealed Battery | Battery with no routine maintenance or electrolyte addition. | CMP—13 |
| Stationary Standby Battery | Battery on continuous float charge, ready for discharge. | CMP—13 |
| Battery-Powered Lighting Units | Backup illumination units with rechargeable batteries. | 517, CMP—15 |
| Berth | Water space for boats between docks or piers. | 555, CMP—7 |
| Bipolar Circuit | DC circuit with two opposite polarity monopole circuits. | CMP—4 |
| Block | City portion enclosed by streets, excluding streets. | 800, CMP—16 |
| Boatyard | Facility for boat construction, repair, and storage. | 555, CMP—7 |
| Artificially Made Bodies of Water | Constructed or modified water bodies for decorative/commercial use. | 682, CMP—17 |
| Natural Bodies of Water | Naturally occurring water bodies like lakes and rivers. | 682, CMP—17 |
| Bonded (Bonding) | Connected for electrical continuity and conductivity. | CMP—5 |
| Bonding Conductor | Ensures electrical conductivity between metal parts. | CMP—5 |
| Equipment Bonding Jumper | Connects portions of the equipment grounding conductor. | CMP—5 |
| Main Bonding Jumper | Connects grounded circuit conductor and equipment grounding conductor. | CMP—5 |
| Supply-Side Bonding Jumper | Ensures conductivity on the supply side of a service. | CMP—5 |
| System Bonding Jumper | Connects grounded circuit conductor and supply-side bonding jumper. | CMP—5 |
| Border Light | Permanently installed overhead strip light. | 520, CMP—15 |
| Term | Definition | Reference |
|---|---|---|
| Bottom Shield | Protective layer for flat conductor cable (Type FCC). | 324, CMP—6 |
| Branch Circuit | Conductors between the final overcurrent device and outlet(s). | CMP—2 |
| Appliance Branch Circuit | Supplies outlets for appliances, no permanent luminaires. | CMP—2 |
| General-Purpose Branch Circuit | Supplies multiple receptacles for lighting and appliances. | CMP—2 |
| Individual Branch Circuit | Supplies only one utilization equipment. | CMP—2 |
| Motor Branch Circuit | Conductors between protective device and motor. | CMP—11 |
| Multiwire Branch Circuit | Circuit with multiple ungrounded and a neutral conductor. | CMP—2 |
| Branch-Circuit Selection Current | Amperes used for motor circuit ratings. | 440, CMP—11 |
| Breakout Assembly | Adapter for multipole to individual branch-circuit connectors. | 520, CMP—15 |
| Broadband | Wide bandwidth data transmission. | CMP—16 |
| Building | Standalone or fire-separated structure. | CMP—1 |
| Floating Building | Building floating on water with permanent wiring. | CMP—7 |
| Manufactured Building | Closed construction building assembled off-site. | 545, CMP—7 |
| Building Component | Subsystem or system integral to a structure. | 545, CMP—7 |
| Building System | Plans and documentation for manufactured building systems. | 545, CMP—7 |
| Bulkhead | Vertical structural wall along the shoreline. | 555, CMP—7 |
| Bull Switch | Wall-mounted safety switch for portable cables. | 530, CMP—15 |
| Bundled | Cables or conductors tied or wrapped together. | 520, CMP—15 |
| Busbar | Noninsulated conductor for power rail connection. | 393, CMP—18 |
| Busbar Support | Insulator supporting busbars in suspended ceiling systems. | 393, CMP—18 |
| Busway | Raceway with factory-mounted conductors. | CMP—8 |
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