Electrical Glossary
Plain-language definitions of the terms, symbols and safety concepts used across the code.
AFCI
A device that detects dangerous arcing and opens the circuit to prevent fire.
AHJ
The official or agency that enforces the code and approves installations locally.
Ampacity
The maximum current a conductor can carry continuously without exceeding its temperature rating.
Bonding
Connecting metal parts so they share a common electrical potential and carry fault current safely.
Box fill
The total volume conductors, devices and fittings occupy inside an outlet box (NEC 314.16).
Conductor
A wire or busbar intended to carry electric current.
Continuous load
A load expected to run for 3 hours or more; sized at 125% of its current.
EVSE
The charging equipment that safely delivers energy to an electric vehicle.
GFCI
A device that cuts power when it senses current leaking to ground, protecting against shock.
Grounding
Connecting a system or equipment to earth to stabilize voltage and provide a fault path.
Overcurrent
Current above the rated value — from overload, short circuit or ground fault.
Voltage drop
The loss of voltage along a conductor due to its resistance; kept under ~3% on branch circuits.
Codex is an independent educational reference. Not the National Electrical Code® and not affiliated with the NFPA. Always verify against the adopted code and your AHJ. · Privacy