Electrical terms, defined
Plain definitions of the electrical words that come up on estimates, inspections and supplier calls, written for electricians. Each term says where it matters on the job and links the Koira calculator, cost guide or template that goes with it.
A
ElectricalAFCI breakerAn AFCI is an arc-fault circuit interrupter: a breaker or receptacle that recognizes the electrical signature of arcing, like a loose or damaged wire, and shuts the circuit off.ElectricalAmpAn amp, short for ampere, is the unit of electric current: how much electricity is flowing through a wire.ElectricalAmpacityAmpacity is the most current a wire can carry continuously without getting hotter than its insulation is rated for.ElectricalAWGAWG, the American wire gauge, is the sizing system for copper and aluminum wire.
B
Shared with SolarBattery storageBattery storage is a home battery system that stores electricity from solar or the grid to use later or during an outage.ElectricalBondingBonding is connecting metal parts together with conductors so they stay at the same electrical potential and any fault current has a clear path.ElectricalBox fillBox fill is the count of wires, devices and clamps inside an electrical box, converted to cubic inches and checked against the box's volume.ElectricalBranch circuitA branch circuit is the wiring from the last breaker or fuse out to the outlets it feeds.Shared with General ContractorBuilding permitA building permit is the local government's approval to do regulated construction work, with inspections at set stages.
C
Shared with Home InspectionCarbon monoxide alarmA carbon monoxide alarm senses the odorless gas from fuel burning appliances, attached garages and blocked vents and sounds an alarm.ElectricalCircuit breakerA circuit breaker is a switch that opens a circuit on its own when the current is too high, protecting the wiring, and can be reset by hand.ElectricalConduitConduit is metal or plastic tubing that wires are pulled through to protect them, used where cable is not allowed or would be exposed to damage.ElectricalConduit bodyA conduit body is a fitting with a removable cover, such as an LB or T, used to turn corners in conduit and give access for pulling wire.ElectricalConduit fillConduit fill is how much of a conduit's inside area the wires take up.Shared with General ContractorCut sheetA cut sheet is the maker's one or two page product sheet with dimensions, ratings and install requirements for a fixture, appliance or material.
D
ElectricalDedicated circuitA dedicated circuit is a branch circuit that serves one appliance or one outlet only, such as a range, dryer, microwave, freezer or EV charger.Shared with Appliance RepairDiagnostic feeA diagnostic fee is the set charge for coming out and finding what is wrong, before any repair is approved.ElectricalDouble tapA double tap is two wires under one breaker terminal that is only made for one.
E
ElectricalElectrical load calculationAn electrical load calculation adds up a home's lighting, appliance and heating or cooling loads by the code method to see what size service or feeder it needs.ElectricalElectrical panelThe electrical panel is the box where the service or feeder splits into branch circuits, each protected by a breaker.ElectricalElectrical rough-inElectrical rough-in is the stage where boxes are set and cable or conduit is run through open framing, before insulation and drywall.ElectricalEV charger circuitAn EV charger circuit is the dedicated higher voltage circuit that feeds a Level two electric vehicle charger in a garage or driveway.
G
ElectricalGFCI outletA GFCI is a ground-fault circuit interrupter: a receptacle or breaker that shuts off power in a fraction of a second when current leaks to ground, such as through a person.ElectricalGround rodA ground rod is a metal rod driven into the earth and connected to the electrical service, giving the system a connection to earth.ElectricalGround wireThe ground wire, or equipment grounding conductor, connects metal parts of equipment and boxes back to the panel so a fault trips the breaker instead of energizing the metal.
K
M
ElectricalMain breakerThe main breaker is the large breaker that shuts off power to the whole panel and protects the service conductors.ElectricalMeter baseThe meter base is the socket box on the outside of the house where the utility's meter plugs in.ElectricalMud ringA mud ring is the raised cover on a square metal box that brings the opening out flush with the drywall and gives the device a mounting point.
N
O
ElectricalOpen circuitAn open circuit is a break in the path, such as a loose wire, a broken conductor or an open switch, so no current flows.Shared with Holiday LightingOutdoor GFCI outletAn outdoor GFCI outlet is a ground-fault protected receptacle in a weatherproof cover, the power source for most holiday displays and landscape lighting.ElectricalOvercurrentOvercurrent is any current above what the equipment or wire is rated for, whether from an overload, a short circuit or a ground fault.
R
S
ElectricalService dropThe service drop is the overhead wiring from the utility pole to the house.ElectricalService entranceThe service entrance is the wiring and equipment that bring utility power into the house, from the service drop or lateral through the meter to the main disconnect.ElectricalShort circuitA short circuit is an unintended low resistance path, such as a hot wire touching a neutral or ground, that lets a large current flow and trips the breaker.Shared with Home InspectionSmoke alarmA smoke alarm is a self contained device that senses smoke and sounds an alarm.ElectricalSubpanelA subpanel is a second panel fed from the main panel by a feeder, used to add circuits in a garage, addition or shop, or when the main panel is full.
T
ElectricalTamper-resistant receptacleA tamper-resistant receptacle has internal shutters that only open when both prongs of a plug push in together, so a child cannot push an object into one slot.ElectricalThree-way switchA three-way switch is one of a pair of switches that control the same light from two places, such as the top and bottom of a stair.ElectricalTransfer switchA transfer switch moves a house's circuits from utility power to a generator and back, so the generator can never feed power back into the utility lines.
V
W
ElectricalWattA watt is the unit of electrical power, the rate at which energy is used.ElectricalWire nutA wire nut is a twist on connector that joins wires in a splice.Shared with Property MaintenanceWork orderA work order is the document that authorizes a job and records what was done: the request, location, tasks, parts, time and sign off.
More for electricians: free electrical tools, templates and guides and how the trade runs on Koira. Or browse the whole glossary.