Ampacity
The maximum current a conductor can carry under its conditions of use without exceeding its temperature rating.
Electrical Glossary
22 core terms used across calculator results, guides, and U.S. electrical field workflows.
Updated May 26, 2026
Terminology follows U.S. electrical practice. Use terms such as bonding, GFCI, AWG, and kcmil when they are the clearest labels for results, drawings, equipment nameplates, and field documentation.
Use terms such as bonding, GFCI, AWG, and kcmil when they are the clearest labels for results, drawings, equipment nameplates, and field documentation.
A
Apparent Power
The product of RMS voltage and RMS current in an AC circuit, measured in volt-amperes.
AWG
American Wire Gauge, the standard U.S. sizing system used for many copper and aluminum conductors.
B
Bonding
The permanent joining of metallic parts to maintain electrical continuity and an effective fault-current path.
Branch Circuit
The circuit conductors between the final overcurrent device protecting the circuit and the outlets or loads served.
C
Continuous Load
A load expected to run at its maximum current for three hours or more, which affects conductor and overcurrent sizing decisions in U.S. practice.
D
Demand Factor
The ratio of maximum demand to the total connected load when a full connected-load sum would overstate actual simultaneous use.
F
Fault Current
Current that flows during an abnormal condition such as a bolted fault, ground fault, or short circuit.
Feeder
All circuit conductors between service equipment, a separately derived system, or another source and the final branch-circuit overcurrent device.
G
GFCI
Ground-fault circuit-interrupter protection that opens the circuit when leakage to ground reaches a hazardous level.
Grounded Conductor (Neutral)
A system or circuit conductor that is intentionally connected to ground as part of the electrical system design.
Grounding
Establishing a conductive connection to earth or to a conductive body that serves in place of earth.
I
Impedance
The total opposition to AC current flow, combining resistance and reactance, measured in ohms.
K
kcmil
A conductor area unit equal to one thousand circular mils and commonly used for larger U.S. conductors.
L
Load
Any equipment or utilization device that draws electrical power from the system.
N
NEC
NFPA 70, the National Electrical Code used as the primary U.S. installation standard for electrical work.
O
Overcurrent Protective Device (OCPD)
A protective device such as a circuit breaker or fuse that opens when current exceeds the permitted value.
P
Power Factor
The ratio of real power to apparent power in an AC circuit, expressed as a decimal or percentage.
S
Service Equipment
The disconnecting means and related equipment that control and protect the electrical supply entering a building or structure.
Short Circuit
An unintended low-impedance connection between conductors at different potentials that allows very high current to flow.
V
Voltage Drop
The reduction in voltage between the source and the load because conductor impedance absorbs part of the available voltage.
W
Watt
The unit of real power equal to one joule per second, commonly used to describe electrical load.