A standby generator isn’t tested by the monthly exercise run on a mild afternoon. It’s tested at 3 a.m. in a January cold snap, when the power drops and the unit has to start cold, carry the load and keep carrying it. Most generators that let people down on that night weren’t broken in summer. […]
A standby generator isn’t tested by the monthly exercise run on a mild afternoon. It’s tested at 3 a.m. in a January cold snap, when the power drops and the unit has to start cold, carry the load and keep carrying it. Most generators that let people down on that night weren’t broken in summer.
Something small on the electrical side had quietly stopped working, and nobody noticed because the power never went out.
This is what I check on the electrical side before winter, and why each item matters here.
Cold does two things to a standby unit. It makes the engine harder to start, and it means everything that keeps the engine ready — the block heater, the battery charger — is working harder and has less margin. A weak battery that turns the engine over fine in September may not do it at -30.
Winter outages also tend to last longer and matter more. If a barn fan, a well pump, heat tape on a water line or a building’s furnace circuits are on that generator, a failed start isn’t an inconvenience. It’s frozen lines, stressed livestock or a building going cold.
Most standby units in Alberta have a block heater (coolant heater) that keeps the engine warm enough to start and take load quickly. It’s usually powered from the building’s supply, not from the generator itself, so it only works while utility power is on — which is exactly when nobody is watching it.
What goes wrong:
A quick check anyone can do: on a cold morning, carefully feel the engine block or the heater hose through the service door. A working block heater leaves it noticeably warm. If it’s as cold as the air, something is wrong. Finding out why — testing the circuit, the receptacle and the element — is electrical work.
The battery charger keeps the starting battery topped up between runs. Like the block heater, it runs off building power, and it often shares a circuit with the block heater. If that circuit is down, both are down.
A charger that has failed doesn’t announce itself. The battery slowly discharges, the weekly exercise run still manages to start the engine for a while, and then one cold week it doesn’t. Many controllers will show a charger or low-battery alarm, but only if someone looks at the display.
On a pre-winter visit I confirm the charger is actually getting power, that it’s charging at the voltage it should, and that the controller isn’t showing a charger or battery warning. Battery age and condition matter too. Batteries are cheap compared to a failed start, and whoever services the engine side can load-test the battery.
The transfer switch is what moves the building from utility power to the generator and back again. An automatic transfer switch (ATS) watches the utility supply, signals the generator to start, waits for the generator’s voltage and frequency to come up, then transfers the load. When the utility comes back, it waits again, transfers back and lets the generator cool down.
Things I look for:
On a manual transfer switch or an interlock setup, check that the person who’ll be operating it during an outage knows the sequence. Do it in daylight, not in the dark during an outage.
This is the one that gets missed. Over a few years, circuits get added to the standby panel: a block heater for a truck, a space heater in a pump house, a freezer, a welder receptacle “because it was close”. The generator was sized for the load it had when it was installed. During an outage in cold weather, everything on that panel tends to come on at once. That’s when a generator overloads and trips its main breaker, or struggles to start a large motor.
Before winter it’s worth confirming what’s on the standby panel, whether the panel directory is still accurate, and whether the total load still fits the generator. That’s panel and load work, the same process as checking whether a panel can take another machine.
On farms I also look at motor loads — ventilation fans, well pumps, waterer circuits. A generator that handles the steady load can still stall or drop out when a large motor tries to start.
A generator is an engine and an electrical system bolted together. The engine side — oil, coolant, fuel, filters, air intake — belongs to a generator service technician or your equipment dealer. Winter fuel issues belong there too: diesel gelling, propane supply in deep cold, natural gas pressure. The electrical side is mine: supply circuits, block heater and charger power, controller supply, transfer switch, distribution and the connected load. Both should be done before winter.
If you’ve got a portable generator rather than a standby unit, the question is different. It’s about how it’s connected to the building — and it has to be through a proper transfer switch or approved interlock, never by backfeeding a receptacle. A backfed generator can energize the power company’s lines and put their crews at risk.
September and October, before the first real cold. Once the first cold snap arrives, everyone with a generator problem finds out on the same night.
I do generator electrical service across Red Deer, Red Deer County and Central Alberta — standby units at shops, farms and commercial buildings. That covers the controller supply, block heater and charger circuits, transfer switches and the distribution the generator feeds. Details are on the generator and light tower service page.
Doesn’t the weekly exercise run prove it works? It proves the engine starts on that day. Most exercise runs don’t transfer the building’s load, so they don’t test the transfer switch or show whether the generator can carry what’s connected. A loaded test once a year covers that.
My generator ran fine last winter. Do I still need a check? The things that fail — a tripped block heater GFCI, a dead charger, a controller left in OFF — can happen at any point in the year and give no warning. A check is short compared to finding out during an outage.
Can I plug the block heater into any outdoor receptacle? It needs a circuit that stays on, isn’t overloaded by other plug-in loads, and is suitable for outdoor use. Where it’s plugged in now is worth looking at if it keeps tripping.
Who do I call if the power is out right now? Report the outage to your power company first. If your generator didn’t start or didn’t transfer, call me. Tell me what the controller display shows and send a photo if you can.
Book a generator electrical check before winter, or send a photo of the generator’s data plate and controller display through the service request form. If the unit is already giving you trouble, call 403-872-8698.
Todd Grasse, Red Seal Journeyman Electrician. Grasse Electric is a licensed electrical contractor in Alberta, insured and WCB covered.
Written by Todd Grasse, Red Seal Journeyman Electrician, Grasse Electric — Red Deer, Alberta. Published September 22, 2026.
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