Why does my microwave trip the breaker every time?

Your microwave is likely tripping the breaker because it's drawing more current than the circuit can handle — either the circuit is overloaded with other appliances, or the microwave itself has a fault.

Microwaves are power-hungry appliances. A typical 1,000-1,200 watt microwave draws 8-10 amps at startup, and many models spike even higher during the first few seconds of operation. If your microwave is sharing a 15-amp circuit with a toaster, coffee maker, or refrigerator, that circuit can easily get overloaded — especially when multiple appliances run simultaneously. The breaker does exactly what it's designed to do: trip before the wiring overheats.

The most common causes are:

• Shared circuit overload — too many appliances on the same 15A circuit
• Aging or weak breaker — breakers can wear out over time and trip at lower loads than they should
• Microwave internal fault — a failing magnetron or capacitor can cause current spikes that trip the breaker
• Undersized circuit — older Ottawa homes often have 15A kitchen circuits that weren't designed for modern appliance loads

What the Ontario Electrical Safety Code says is that kitchen countertop appliance circuits should be 20-amp dedicated circuits — and modern code requires at least two of these in a kitchen. If your home was built before the mid-1990s, there's a good chance your kitchen wiring doesn't meet current standards. This is especially common in older Ottawa neighbourhoods like Centretown, Westboro, and Glebe where homes date back to the 1950s-70s.

Here's what you should check first (safely, with the power off): Is anything else plugged into the same circuit as the microwave? Try unplugging everything else on that circuit and running the microwave alone. If it still trips, the problem is either the microwave itself or the breaker — both need professional attention.

Do not ignore a repeatedly tripping breaker. A breaker that trips constantly is under stress, and a failing breaker can eventually stop tripping when it should — which is when wiring overheats and fires start. If the breaker feels warm to the touch or you notice any burning smell near your panel, treat that as an emergency.

The proper fix is usually a dedicated 20-amp circuit for the microwave, which runs around $300–$500 in the Ottawa market and requires an ESA permit. If your kitchen is due for a broader electrical update, it's worth having an electrician assess all your countertop circuits at the same time.

For a free estimate on adding a dedicated microwave circuit, feel free to reach out to Electrical Ottawa — we can assess your panel capacity and get the work permitted and inspected properly.