Why do my lights flicker every time the heat pump kicks on in my New Brunswick home?

A brief flicker when your heat pump starts is usually normal — the compressor motor draws a large surge of current (called inrush current) that momentarily drops the voltage on your home's electrical system. However, if the flickering is severe, lasts more than a second, or happens on every cycle, it could indicate an undersized panel, a loose connection, or a problem with your electrical service.

Heat pumps are incredibly popular in New Brunswick right now, largely thanks to NB Power rebates that make the switch from oil heat very attractive. But many older homes weren't designed for the electrical load a heat pump adds. A typical heat pump compressor draws 15 to 25 amps at 240V when running, but the startup surge can hit 40 to 60 amps for a fraction of a second. If your panel is a 100 amp service that's already loaded with an electric dryer, electric range, and hot water heater, that startup surge can cause noticeable voltage drops throughout the house.

When flickering is a concern. If your lights dim significantly (more than a brief blink), if the flickering lasts several seconds, or if you notice lights dimming at random times unrelated to the heat pump cycling, you should have a licensed electrician investigate. These symptoms can indicate loose connections at the panel, a deteriorating main breaker, corroded service entrance connections, or an issue with the NB Power service drop to your home.

Common fixes include installing a hard-start kit on the heat pump compressor (around $150 to $300 installed), which reduces the inrush current by 30 to 50 percent. If your home is on 100 amp service, upgrading to 200 amps will eliminate the issue entirely and give you capacity for future additions like an EV charger. A loose connection at the panel — which is a genuine fire hazard — needs immediate attention from a licensed electrician.

One important check before calling an electrician. If the flickering is only in one area of your home, it might be a loose connection at a specific outlet or switch rather than a panel issue. Try turning off the breaker for that area and checking if the lights on other circuits still flicker when the heat pump starts. If they don't, the issue is isolated to that circuit. If they do, it's a panel or service issue.

A TSANB-licensed electrician can perform a load analysis on your panel, check all connections with a thermal camera, and recommend the most cost-effective solution. In many New Brunswick homes, a combination of a hard-start kit and tightening panel connections resolves the issue for under $500.

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