Lights flickering in the house: when it’s urgent

One light, one room or the whole house: the first check

The first question to ask yourself: what exactly is flickering? One lamp, one room or the entire house does not call for the same response.

Ontario’s electrical safety body, the Electrical Safety Authority (ESA), places the loose connection that can make lights dim, surge or flicker in three possible spots: a lighting circuit, a light fixture or the home’s electrical service.

Bulbs, LEDs and dimmers: what you can check

If a single light flickers and it is controlled by a dimmer, start with the bulb. This check doesn’t involve opening anything: you just read the packaging.

The Government of Québec points it out: a dimmer that is incompatible with the bulbs in place can cause flickering or disrupted lighting and a limited dimming range. At Sinopé, a dimmer manufacturer, technical support generally attributes an LED flickering on a dimmer to compatibility or to a brightness level set too low. Leviton, another manufacturer, adds wiring, load type and configuration to the list.

What you can look at yourself:

1. The label on the bulb. On a dimmer, an LED bulb must be designed for dimming: look for “dimmable” on the packaging.
2. The dimmer. It must be rated for LEDs; Leviton warns that older models are not always.
3. The minimum level. On some dimmers, manufacturers suggest raising the minimum dimming level to fix flickering at low brightness. Sinopé then says to check that the bulb is compatible with dimmers if the flickering persists.

Choosing a dimmer that works with LEDs, and what to know before having one installed: see our guide LED dimmers: choosing a compatible model.

Replacing the dimmer itself is another matter. Sinopé requires its dimmers to be installed by a certified electrician, and the CMEQ puts it plainly: in your home, only a master electrician can perform electrical work.

When a large appliance starts

Lights that dip for a short moment when an appliance starts are not the emergency sign we describe: that one affects the whole house at once, and is not limited to the moment an appliance switches on.

Hydro-Québec explains these dips. In its bulletin on voltage dips, it lists motor starting, a sudden change in load and an electrical fault among the causes that come from customers’ installations. Among the causes of voltage variations, it also counts the use of an appliance that can trigger a sudden current draw. Its document on voltage quality states that a rapid voltage change, caused by load variations or by switching on the grid, can produce a noticeable change in the brightness of the lighting.

An electrical fault is on the same list. If the flickering doesn’t line up with anything starting and it affects several rooms, it is an emergency: call us at 438-542-7304.

What a power surge is, and where it comes from: see our guide What is a power surge, and where does it come from?

The whole house flickers: a loose connection

When every room flickers together, or some bulbs shine brighter than usual, our master electricians see a loose connection, often on the neutral. Appliances can then receive too much voltage and burn out.

The danger isn’t limited to appliances. According to the ESA, a loose connection that makes lights dim or flicker can present a risk of electric shock or become a fire hazard.

A real case shows it. In British Columbia, Technical Safety BC investigated a fire (incident report dated January 14, 2020). Flickering lights, outlets and appliances working intermittently: the organization sees them as classic symptoms of poor or loose conductor terminations, which drive temperatures up. The occupant had noticed these signs about six weeks before the fire.

While you wait for us, unplug your electronic devices. Has an appliance stopped working after the episode? See our guide Appliances damaged by a power surge.

It’s urgent if…

Phone us right away at 438-542-7304 if:

• the flickering affects several rooms, or the whole house, at the same moment;
• some bulbs shine brighter than usual;
• you smell burning, or a switch or an outlet heats up, turns black or crackles;
• the electrical panel becomes abnormally hot.

Every type of electrical emergency: our page 24-hour emergency electrician.

Electrician or Hydro-Québec: who to call first?

Us. Call us at 438-542-7304; we’ll tell you if Hydro-Québec needs to step in.

The cause can be in the house or on the grid. Among the causes of voltage dips, Hydro-Québec lists a motor starting at a customer’s home as well as, on its side, vegetation, an animal, a collision, the weather (wind, lightning, rain, freezing rain) or equipment failure. The Government of Québec, for its part, includes power drops among the situations to entrust to a master electrician.

Repairs: a job for a master electrician

On site, the master electrician makes the area safe, then runs a diagnosis to find the exact cause of the problem. For a flickering light, our rule is simple: we find the cause before replacing anything.

Replacing an outlet or a light fixture is electrical work. In the home, the CMEQ reserves it for a master electrician. Our master electricians hold RBQ licence 5815-0137-01 and are members of the CMEQ.

A flickering light with no sign of an emergency? Troubleshooting is part of the everyday work of our General electrical work (in French) service. If a breaker trips as well, see our guide Breaker keeps tripping: the causes and what to do.

Frequently asked questions