What a surge is
A surge is a brief spike in voltage, lasting a tiny fraction of a second. Your electronics are designed for a steady 120 V. A large spike can damage them outright, and many small ones can wear them out early.
Edmonton gets summer thunderstorms, but lightning is only part of the story. A good share of surges start inside the home or building, every time a motor or compressor switches on and off. Utility switching and faults on the grid add more.
How a surge protective device works
A surge protective device, or SPD, sits between your wiring and ground. At normal voltage it does nothing. When the voltage spikes above its clamping level, it diverts the excess energy to ground in a few billionths of a second, then goes back to waiting.
Two ratings matter when comparing devices. The clamping or voltage protection rating tells you how high the voltage can rise before the device acts; lower is better. The surge current rating tells you how much energy it can handle; higher means a longer life. Joule ratings on power bars are a rough guide only.
Each time an SPD absorbs a large surge, it wears a little. Most whole-home units have an indicator light or flag that shows when the protection is used up and the device needs replacing.
Layered protection
No single device catches everything. The best results come from layers:
- A whole-home SPD at the panel protects every circuit, including hard-wired equipment like the furnace, range, heat pump and EV charger that cannot plug into a power bar.
- Point-of-use surge strips at computers, TVs and networking gear catch the smaller surges that start inside the house.
- Data line protection on incoming cable, phone or antenna lines, which surges can also travel along.
A basic power bar only adds receptacles. Look for a surge protector certified to a recognised Canadian standard, and replace it if its protection light goes out.
Is it worth it for your home or business?
Whole-home surge protection makes the most sense when you have a lot to lose. Consider it if you have:
- A modern furnace, heat pump or tankless water heater with electronic controls.
- An EV charger, solar inverter or battery storage.
- Smart appliances, a home office or a home theatre.
- A rural or acreage service on a long overhead line.
- In a business, point-of-sale systems, refrigeration, servers or controls that would stop work if damaged.
For most existing homes, whole-home surge protection is an optional upgrade rather than a code requirement. Whether a particular installation needs it depends on the code edition and the equipment, so ask your electrician.
No surge protector can stop a direct lightning strike to your building, and it does not replace a proper ground. It greatly reduces everyday surge damage, which is where most of the cost comes from.
Surge protection for businesses
For a business, a surge rarely means one dead TV. It means a point-of-sale system that will not boot on a Saturday, a walk-in cooler controller that stops, or a server that loses data. The cost of downtime is usually far larger than the cost of the equipment.
Commercial and industrial surge protection is usually designed in layers: SPDs at the main switchboard, at distribution panels feeding sensitive loads, and at the equipment itself. Motor drives, controls and refrigeration benefit most. Pair it with UPS systems for equipment that cannot tolerate even a short outage.
Installation and upkeep
A whole-home SPD mounts at or inside your main panel and connects to a breaker. Short, direct connections make it work better, which is one reason it is installed by a licensed electrician. It is often done alongside a panel replacement or service upgrade, when the panel is open anyway.
What affects cost is the type and rating of the device, whether the panel has a space for its breaker, and whether the grounding needs attention. Check the indicator light once or twice a year, and after any big storm or power event.
Alberta Electrical installs surge protection for homes and businesses, and can check your grounding and bonding at the same time.
Common questions
Does a whole-home surge protector replace my power bars?
No. It handles large surges from outside and protects hard-wired equipment. Keep point-of-use surge protectors for sensitive electronics.
How long does a whole-home SPD last?
It depends on how many surges it absorbs. Most have an indicator that shows when protection is spent. Check it after storms and replace it when it says so.
Is surge protection required by code?
For most existing homes it is optional. Some installations and equipment may have requirements; your electrician will confirm for your project.
Will surge protection help with a power outage?
No. An SPD only limits voltage spikes. For outages you need a UPS for short gaps or a standby generator for longer ones.
Can I install a plug-in whole-home protector?
A true whole-home SPD connects inside or at the panel and must be installed by a licensed electrician. Plug-in units are point-of-use devices only.
Codes and permit rules change and every building is different. For work on your system, talk to a licensed electrician and your local permit authority.