How a whole-house surge protector works

What a whole-house surge protector is

Canadian standards speak of “surge protective devices” and sort them into three types: two that stay wired in for good, Types 1 and 2, and a third for devices with a cord or that plug into an outlet, Type 3. A whole-house surge protector is the permanently connected kind: once installed, it covers every circuit the panel feeds.

The Government of Canada calls it a “whole home surge protector”. You will also see the term panel surge protector.

An uninterruptible power supply (UPS) does not play this role: the CSA standards for Types 1 and 2 do not consider it a surge protective device.

Where surges come from: What is a power surge, and where does it come from.

Type 1 or Type 2: where it connects

What sets the two permanently connected types apart is where they sit relative to the main breaker.

• Type 1. Its standard provides for installation between the utility’s service transformer and the line side of the service equipment’s overcurrent device, in other words before the main breaker; it may also be installed after it. The Alberta sheet assigns it to large surges, such as those from a lightning strike on the power grid.
• Type 2. It goes on the load side, after the main breaker. According to the Alberta sheet, it targets surges from outside as well as those that start inside the building.

In both cases, wire length matters: the Alberta sheet explains that short wires give the surge current a more direct path, and so more effective protection.

How it protects: ground does the work

The principle fits in one sentence: during a surge, the surge protector diverts the surge current away from the connected equipment and sends it to ground.

That is why grounding matters. Ontario’s Electrical Safety Authority notes it for surge protectors used with computer or entertainment equipment: without a ground reference, they do not work. Hydro-Québec, for its part, recommends having the electrical system and its grounding inspected by a master electrician, particularly when buying a home.

A surge protector does not last forever. Each surge it diverts can degrade it slightly, and most models have an indicator that signals the end of its life, according to the Alberta sheet.

How grounding is checked, and when to redo it: Grounding your home (in French).

Is a whole-house surge protector mandatory?

For us, the answer is clear: no rule requires one, but it protects electronics.

In Québec, electrical installations follow the Québec Construction Code, Chapter V (Electricity), which adopts the 25th edition of the Canadian Electrical Code, CSA C22.1:21, with amendments specific to Québec. The code’s official index places surge protective devices under Rule 26-420. The Québec amendments themselves do not mention surge protectors.

Many pages you find online come from the United States and cite their own code. In Québec, it is the Québec Construction Code, based on the Canadian code, that applies.

What it protects, and its limits

For the Government of Canada, a whole home surge protector is worth considering: it helps prevent damage to appliances such as your refrigerator, stove or microwave.

That does not make it the last word for every device. The Alberta sheet describes Type 3, placed in front of a specific device, as an extra layer of protection against residual surges. A surge protector power bar and panel protection work together: Power strip, surge protector or panel protection?

As for lightning, the Alberta sheet speaks of large surges caused by a direct lightning strike on the power grid, and that is the role it gives to Type 1. It says nothing about lightning striking the house itself.

And protection remains the customer’s job: Hydro-Québec points out that it is up to each customer to protect their appliances.

Getting one installed

A whole-house surge protector connects inside the electrical panel. The Corporation des maîtres électriciens du Québec points out that at home, this work is reserved for master electricians, with fines of $5,000 to $200,888 for offenders.

The device must also be approved: the Régie du bâtiment du Québec prohibits selling or installing unapproved electrical equipment.

Adding an EV charger, a generator or solar panels? See also our EV charger, generator and solar panel pages.

The installed price, the brand we install and how the job goes: Whole-house surge protector installation.

Frequently asked questions