Reference
27 terms
Electrical words,
in plain English.
Every trade has words that stop being explained once everyone in the room knows them. These are the ones you are most likely to meet on a quote, a spec sheet or an inspection report — written for someone who does not do this for a living.
A
Branch wiring run in aluminum rather than copper, common in Canadian homes built between the mid-1960s and late 1970s.
Aluminum expands, contracts and oxidises differently to copper, so the connections at outlets and switches loosen over time and heat up. The wire itself is rarely the problem; the terminations are, and they can be remediated.
Electricity jumping a gap it should not, across a loose terminal or damaged insulation, producing intense localised heat. It is the most common cause of electrical fires.
You may hear it as a buzz or crackle, smell it as hot plastic, or see it as scorching around a faceplate. Any of the three is a reason to switch that circuit off and call someone.
B
A switch in your panel that cuts a single circuit when it draws more current than the wire behind it can safely carry.
A breaker that trips is doing its job. A breaker that trips repeatedly is reporting a fault: either too much plugged into one circuit, or something wrong in the wiring. Resetting it over and over treats the alarm rather than the fire.
D
Two wires jammed under a single breaker terminal designed for one. It works until the connection loosens and starts heating.
E
The licence a company must hold to carry out electrical work for hire in Ontario. Ontario law requires it to be displayed, and you are entitled to ask for the number.
It is held by the company, and is a different credential from a Master Electrician licence, which is held by a person. Copper Bee holds a contractor licence.
A licensed electrician assessing the system you already have and writing up what is unsafe, what is aging, and what it would cost to put right.
Different from an ESA inspection, which closes a permit on work just done and ends in a certificate only ESA can issue. Also different from a home inspection, which covers the whole building as a generalist.
An inspection by the Electrical Safety Authority that closes a permit on work just completed, ending in a Certificate of Inspection. Only ESA can issue one.
Worth separating from an electrical inspection by a contractor, which assesses the condition of a system that already exists and produces findings, not a certificate. If someone has asked you for a Certificate of Inspection, only ESA can provide it.
ESA permit
Process & paperwork
Also called electrical permit · notification of work
The notification a licensed contractor files with the Electrical Safety Authority before doing work that requires inspection. We pull it; you never call ESA.
G
A device that cuts power within milliseconds if current starts leaking to ground, through water or through a person. Required near sinks, outdoors and in bathrooms.
It protects people, which is what separates it from an ordinary breaker: a normal breaker is sized to protect the wire, and the current that will kill you is far below the current that will trip it.
The system that gives stray current a safe path back instead of through you: grounding ties the system to the earth, bonding ties metal parts together so they sit at the same voltage.
H
Connected permanently into the building wiring rather than plugged into an outlet. Required for some chargers and for every smoke alarm on a modern circuit.
I
Installed price
Process & paperwork
Also called all-in price · price installed
The figure that covers the equipment, the labour, the breaker and cable, and the ESA permit, so the number you are quoted is the number you pay.
K
Wiring used in houses built before roughly the 1950s, with no ground wire and cloth-and-rubber insulation that hardens and crumbles with age.
It is not illegal to have, and intact runs can still be serviceable. It becomes a problem when it has been buried under insulation, extended by an amateur, or asked to carry loads it was never designed for — and many insurers now ask about it directly.
L
A 240-volt car charger, running off the same supply as an electric dryer, which adds range several times faster than a regular wall outlet.
Level 1 is the cord that comes with the car plugged into an ordinary socket. It works, and it is slow enough that most people who drive daily move to Level 2 within a year.
The arithmetic that adds up everything drawing power in a house to work out what service size it actually needs, set out in OESC Rule 8-200.
It is not a simple sum of every nameplate rating, because the code assumes you will never run the stove, the dryer, the A/C and the car charger at full tilt simultaneously, and applies demand factors accordingly.
Our panel calculator runs the same rule so you can see roughly where you stand before anyone visits.
A device that watches how much power the house is using and throttles or pauses a big load, usually an EV charger, so the total never exceeds your service.
It is the cheaper answer when the only thing standing between you and a car charger is capacity. Instead of upgrading the whole service, you let the charger wait its turn.
M
The single large breaker at the top of your panel that cuts power to the whole house. Its rating is your service size.
If you want to know what service you have, this is where to look: the number printed on the main breaker handle is your answer.
The weatherproof housing on the outside of your house that the utility meter plugs into, between the incoming service cable and your panel.
N
The standard naming system for North American plug shapes. NEMA 14-50 is the big 240-volt socket most plug-in car chargers and ranges use.
P
Replacing the breaker panel inside your home, the box the circuits land in, usually with the main breaker at the same time.
Adding breakers to a panel you already have is a different thing; that only fills space that was already there. A service upgrade is different again, because it also replaces the equipment outside. See the next entry: the difference is a different job at a different price.
It needs an ESA permit and an inspection, and the power has to come off while the circuits are moved across.
S
The pipe carrying the overhead service line from the utility pole down to your meter. It is the part most often damaged in a storm.
Where the utility's responsibility ends and yours begins varies, so if it is damaged, call your utility before anyone else. They will tell you which side is theirs.
The total amount of electricity your house can draw from the grid at once, measured in amps. Most Ontario homes are 100A or 200A.
It is set by the main breaker, the meter base and the cable running in from the street, so raising it is a bigger job than swapping a panel. It is also the number that decides whether you can add an EV charger, a heat pump or a hot tub without further work.
Replacing the panel and the equipment outside it: meter base, and often the mast or the incoming cable. This is what actually raises how much power the house can draw.
A panel upgrade stops at the wall. A service upgrade goes through it: the grey box your hydro meter sits in, and sometimes the pipe and cable feeding it, get replaced too.
You need one if you are raising your service size, or if the meter base is cracked or rusted, or the wires entering it are wrapped in frayed cloth rather than smooth plastic. It involves the utility disconnecting and reconnecting you, so it is scheduled rather than same-day.
A hardwired, interconnected alarm covering both smoke and carbon monoxide, an odourless gas a smoke sensor alone cannot detect.
Interconnected means one going off sets them all off, so an alarm in the basement wakes you upstairs. Ontario sets rules for where they must be and how often they are replaced.
A device fitted at the panel that absorbs voltage spikes from lightning, from the grid, or from your own appliances, before they reach anything plugged in.
A power bar with surge protection covers one outlet. A panel-mounted one covers every circuit, including the hardwired things you cannot put a power bar on: the furnace, the A/C, the garage door opener.
T
The switch that disconnects your house from the grid and connects it to a generator, so power cannot flow back down the line toward utility crews.
This is the part that makes a standby generator legal as well as safe. Backfeeding a generator into the house wiring without one can electrocute someone working on the line outside.