Why are my lights flickering?

Flickering lights get ignored longer than almost any other electrical symptom, because most of the time nothing bad happens next. A bulb flutters, you shrug, life continues.

Most of the time that instinct is right. But flickering is one of the few symptoms where the harmless version and the serious version look similar from the couch, and the serious version is genuinely serious. So it’s worth knowing which is which.

Start here: is it one light, one room, or the whole house?

That single question sorts most of it.

One fixture. Almost always the fixture, the bulb, or the switch. Low stakes.

One circuit or one room. Usually a loose connection somewhere on that circuit. Worth fixing, not an emergency.

The whole house, on and off, especially with brightness that varies. This is the one. Stop reading the rest and skip to the section below on loose neutrals.

The harmless explanations

Something big just turned on. A furnace blower, a well pump, a compressor, or an air conditioner draws a large surge of current for a moment when its motor starts. Lights on the same service dip briefly. If your flicker happens at the exact moment the furnace kicks in and lasts a fraction of a second, that’s normal behaviour on most services. It becomes worth investigating if it’s getting more pronounced over time, which can mean the service is closer to its limit than it used to be.

LED and dimmer mismatch. The single most common flicker call we get since everyone switched to LED. Old dimmers were designed for incandescent bulbs that drew far more power, and they don’t regulate a small LED load smoothly. The fix is usually a dimmer rated for LED loads, and sometimes a different bulb. If your flickering started when you changed the bulbs, this is your answer, not the wiring.

A loose bulb or a worn socket. Try tightening it. It costs nothing and it solves a surprising share of single-fixture cases.

The ones worth fixing properly

A loose connection on the circuit. Terminal screws work loose over decades of heating and cooling. A backstabbed receptacle, where the wire was pushed into a spring clip on the back of the outlet rather than wrapped around the screw, is a classic offender. The symptom is one circuit flickering, sometimes worse when someone walks across the floor above.

This one matters because a loose connection is a warm connection, and a warm connection arcs. That’s the mechanism behind a lot of wire fires. It’s cheap to fix and worth not putting off. If your house has aluminum branch wiring, this failure mode is more likely and the fix has specifics to it, which we covered in aluminum wiring in BC homes.

A failing breaker or a bad panel connection. A breaker that’s worn out, or a bus connection that’s corroded or loose, can cause everything downstream to flicker. Older panels and the brands with a poor track record are more prone to this. If the flickering is accompanied by breakers that trip for no clear reason, read why does my breaker keep tripping, because the two symptoms often share one cause.

The pattern that means call today

Here’s the one to take seriously. Lights across the whole house flickering, with brightness that varies from room to room or from one moment to the next, sometimes with electronics behaving strangely or appliances dying earlier than they should.

That pattern points at a loose or failing neutral at your service, either in the panel, at the meter, or on the utility’s side. Your home’s 240-volt supply is split into two 120-volt legs that share a neutral. When that neutral connection degrades, the two legs stop being balanced against each other. One side of the house can see well over 120 volts while the other sees well under. High voltage cooks electronics quickly, and the connection itself is a heat and fire risk.

That’s not a wait-and-see symptom. Call an electrician, and if you smell anything hot near the panel or the meter, call BC Hydro too. This is the one flickering pattern where the cost of ignoring it is measured in fried appliances at best.

When flickering is really a capacity problem

There’s a slower version worth mentioning. If the dip when a large appliance starts has gotten noticeably worse over the years, and especially if you’ve added load since the panel went in, the service may simply be stretched. That’s not a fault to find, it’s arithmetic, and we walked through how to check it in how many amps does my house need. The fix is a panel and service upgrade, which usually runs $4,000 to $6,000 depending on the service, the panel location, and what BC Hydro’s side involves.

What we actually do about it

Tracing a flicker is measurement. We check voltage on both legs under load, look for imbalance that points at a neutral, thermally check terminations in the panel, and work outward through the affected circuit’s devices to find the loose or damaged connection. Most of the time we find it in a device box, and the repair is small once you know where to look.

That’s ordinary repairs and troubleshooting work, and older housing stock has predictable patterns. A postwar Vancouver house with decades of added circuits fails differently than a 90s build.

The short version

One fixture flickering is a bulb or a switch. One room is a loose connection, worth fixing soon. The whole house with varying brightness is a neutral problem, and that one gets a phone call today rather than a note on the fridge. If you’re in the last category, or you’re not sure which category you’re in, get in touch and we’ll find out.