Electrical Definitions (By An Electrician & His Wife)

By thewriteDuffy •  Updated: 05/08/24 •  6 min read

This website is a collaboration between myself, a writer, and my husband, a master electrician with 20+ years in the trade (check out our about page here). Needless to say, our understanding of electrical terms is very different.

This is a problem when I ask him what I think are easy questions in order to deliver quality advice to you, our fellow homeowners who just want to know how to properly renovate or build the home of your dreams. While I’m expecting an easy answer, he sometimes finds it hard to avoid some of the electrical terms he uses on a daily basis.

So, in the interest of having a resource I can point you to when things get a bit too technical or full of jargon and slang, we’ve created this list of electrical definitions to help us all stay on the same page. I’ve also tried to leave out the stuff we’ll never need here like diodes and electrons.


AC Current

AC current, or alternating current, is an electric current that changes direction many times a second at regular intervals. 

AFCI (Arc Fault Circuit Interrupter)

An electrical device in your circut panel that cuts power to prevent electrical fires when the AFCI detects minute differences in electrical current caused by a punctured wires, shorts, and arcing. See also GFCI.

Ampere (or AMP)

an electrical unit of measurement that measures the rate of electrical charge flowing through the system. Electrical service panels and circuit breakers are usually measured in AMPS.

Ampere Meter (or ammeter)

An ammeter is an instrument for measuring either direct (DC) or alternating (AC) electric current, in amperes. An ammeter can measure a wide range of current values because of a shunt in parallel with the meter that directs the majority of the current through the meter mechanism at high values, meaning only a small portion actually flows through the meter itself. 


A short circuit where the electricity litterlly jumps, or archs, to the nearest metal.

AWG (American Wire Gauge)

AWG, also known as the Brown & Sharpe Gage, is the North American system of standard wire sizes that start with the lowest numbers (6/0) for the largest sizes and increase in number as the wire decreases in size. In other words, the higher the gauge number, the thinner the wire.

The AWG standard includes copper, aluminum and other wire materials. Typical household copper wiring is AWG number 12 or 14.

You’ll often hear electricians simply refering to wire as “12-gage” or “14-gage” when talking about home wiring, this is the size scale that comes from.



Electricity flows in a circuit, from the service panel to the various outlets and fixtures, and then back to the panel. Each circuit is rated for AMPS (See above) which are controlled by a circuit breaker (see below).

A home circut breaker is commonly made for 15 or 20 Amps. A circuit controlled by a 15-amp breaker is capable of safely carrying 1,440 watts (15 AMPS x 120 Volts x 80% for safety).

Ten outlets is usually the maximum for a circuit, but it can be fewer if those outlets are serving appliances that draw a lot of electricity such as a fridge or window air conditioner.

Circuit Breaker

A protective device in an electrical panel that interrupts the flow of electricity in the electrical circuit when there is excess load or a short.

Older service panels used fuses, but they were replaced by circuit breakers, which are easier to reset.


Electrical System

The blanket term for all the electrical components used to supply electricity to your home. Your electrical system includes many individual components like panels, wiring, plugs, fixtures, etc.



In plumbing and electrical, the “finishing” is a building stage in the constrtuction of a new home.

In this stage, the walls been closed in and all of the lights, fixtures, and plug plates are now being installed. See also Rough-In.


Before circuit breakers, fuses were the devices used to interrupt a circuit in the event of a problem. A fuse is a strip of wire that can melt and break an electric circuit if the current gets too great. After fixing the cause of blown fuse, it’s necessary to replace it with a similar one of the same size and rating.


GFCI (Ground Fault Circuit Interrupter)

A GFCI monitors the amount of current flowing from hot to neutral; if there is a difference — even as small as 4 or 5 milliamps, which is too small to activate a fulse or circuit breatker — it cuts the electricity off in a fraction of a section. This protects people from severe electric shocks and electrocution. See also AFCI.


Junction Box

A metal box where the electrical separate lines are run off the circuit to the receptables and lights.


Kilowatt (kW)

A kilowatt is a unit of electrical measurement; one kilowatt is equal to 1000 watts. Also see watts.

Kilowatt-hour (kWh)

One kilowatt hour (kWh) is equivalent to 1,000 watts of power consumed for one hour. kWh is the unit of electricity sold; you’ll see it on lightbulbs mostly.

Knob and Tube

Knob and tube wiring is the oldest form of electrical wiring, which was installed until about 1945.

Thsi system featured two separate wires (one black and one white) for each circuit. This is different from today’s electrical wires, which combine black, white and ground wires.

The words “knob and tube” refer to the ceramic knobs the wite was strung from and the tubes used to protect the wire where it passed through joists and studs.


PVC (Polyvinyl Chloride) Conduit

PVC is also used as plumbing pipes, but in electrical, PVC conduit is used to protect wires, often in underground and other wet location applications.



In plumbing and electrical, the “rough-in” is a building stage in the constrtuction of a new home.

In this stage, the pipes or wires have been installed but the walls and floors have not been closed in and the fixtures have not been connected. See also Finishing.


Service Panel

All electricity entering a home first goes into a service panel, which is a wall-mounted box, usually placed in the basement, that features breakers for individual circuits.



An electrical unit of measurement that measures the electrical preassure exerted by a power source.

In Canada, most electrical service is 120 volts or 240 volts.

Voltage Drop

Voltage drop is when voltage is lost through all or part of a circuit due to impedance, which could be as simple as the length of the wire being used.

For example, if your running a a 10-foot, 14-gauge extension cord, you will be able to use that cord for something that’s 120 Volts, but that same cord at 200 feet will only be good for running something that needs about 103 Volts. 


A voltmeter is simply an instrument used to measure the force of the current in volts.



An Electrical unit of measurement for the amount of electrical energy flowing to a particular fiture in an electrical system.

All the lights and appliances that you run off your circuits are rated for wattage — the amount of electricity tey consume.


At home, April is a mom, wife, and DIY darling. Among other home projects, she helped her husband Dan renovate their 1986 bungalow and is currently designing and decorating the 2023 custom home they are building themselves. Professionally, April is a writer, author, and online marketer with 15 years of experience writing for newspapers and magazines, building online authority websites, and publishing books.