Total power loss is usually the utility’s problem. Partial power loss — some rooms dark, others fine — is almost always yours, and it’s worth understanding what you’re dealing with before you start flipping things.
First: is it just you?
Look outside. If the street is dark, it’s an outage and there’s nothing to diagnose. If your neighbours have lights and half your house doesn’t, keep reading.
The three usual causes
1. A tripped breaker
The most common by far. A breaker that has tripped often doesn’t look obviously off — it can sit in a middle position that resembles “on.”
To check: open the panel door and look along the row. Push any suspect breaker firmly to off first, then back to on. Half-resetting a breaker is the most common reason people conclude “it’s not the breaker.”
If it trips again immediately, stop. It is doing its job. Something on that circuit is faulted or overloaded, and resetting it repeatedly turns a protected fault into an unprotected one.
2. A tripped GFCI
This one catches nearly everyone.
GFCI protection is required in bathrooms, kitchens, garages, outdoors and unfinished basements. Crucially, one GFCI outlet often protects several other ordinary outlets downstream of it.
So a dead outdoor outlet, or dead garage outlets, or a dead outlet behind the fridge, is frequently caused by a tripped GFCI somewhere else entirely — commonly in a bathroom, a garage, or an unfinished part of the basement.
To check: find every GFCI outlet in the house — they have TEST and RESET buttons — and press RESET on each. Check the bathrooms, the garage, the exterior and the utility room. People routinely find one they’d forgotten existed.
If it resets and stays reset, you’ve solved it. If it trips again, something on that circuit has a fault.
3. A lost leg of your service
Less common, and more serious.
Your home is fed by two 120-volt legs that combine to give 240 volts. If one leg is lost — a failed connection at the service, a utility-side fault, a problem at the meter — roughly half your house goes dark while the other half keeps working, and your 240-volt appliances behave strangely.
The tell: about half the circuits are dead, spread across the house rather than grouped in one area, and things like the dryer or stove misbehave rather than simply not working.
This one is not a homeowner fix. It can also produce dangerous voltage conditions on the working half. If this is what you’re seeing, call an electrician.
When to stop troubleshooting and call
Immediately, if any of these are true:
- Burning smell, hot plastic, or smoke — anywhere, however faint
- Scorch marks or discolouration on an outlet, switch or the panel
- The panel is warm, buzzing, or crackling
- Water anywhere near the panel — don’t touch it at all
- Lights flickering across the whole house, or brightening and dimming
- A breaker that trips again immediately each time you reset it
- About half the house is dead — the lost-leg pattern above
→ Emergency Electrician — 24/7
What not to do
- Don’t remove the panel cover. The door is fine. The cover is not.
- Don’t keep resetting a breaker that keeps tripping.
- Don’t run extension cords from working circuits as a workaround. That’s how an inconvenience becomes an overload.
- Don’t ignore it because it came back on. Intermittent is usually a loose connection, and loose connections generate heat.
If it turns out to be nothing
Sometimes it is a GFCI in a garage nobody had thought about for four years. That’s a good outcome, it costs you nothing, and we’d rather you found it yourself than paid us to find it for you.
Still dark? We answer 24 hours a day. Call (403) 690-3994.