How do heated mirrors work, and do they need a dedicated electrical circuit?

Heated mirrors — also called anti-fog or defogger mirrors — use a thin heating element bonded to the back of the mirror glass that warms the surface just enough to prevent condensation from forming after hot showers. They are increasingly popular in GTA bathroom renovations, especially in homes where the bathroom mirror fogs up heavily during Toronto's humid summer months or after long hot showers in winter.

The technology is straightforward. A low-wattage heating pad (typically 40–80 watts for a standard vanity mirror) is adhered to the back of the mirror glass. When activated, it raises the mirror surface temperature a few degrees above the dew point, preventing moisture from condensing on the glass. Most heated mirrors available through GTA suppliers use a simple on/off switch — some are hardwired to the bathroom light switch or exhaust fan switch so the defogger activates automatically when you turn on the lights or fan. Higher-end models include a separate dedicated switch or a timer that runs the defogger for 15–30 minutes after activation.

Regarding whether a heated mirror needs its own dedicated circuit — in most cases, no. A standard heated mirror draws only 40–80 watts, which is comparable to a single incandescent light bulb. This is a very small electrical load that can typically share an existing bathroom circuit with the vanity lights, exhaust fan, and GFCI outlet without approaching the circuit's capacity. A standard 15-amp, 120-volt bathroom circuit can handle 1,800 watts; your mirror defogger, vanity light, and exhaust fan together rarely exceed 300–400 watts combined.

However, the installation itself still requires a licensed electrician in Ontario. Even though the power draw is modest, hardwiring a heated mirror involves making electrical connections inside the wall, potentially running new wiring from a switch or junction box to the mirror location, and ensuring the connection meets Ontario Electrical Safety Code requirements. An electrical permit and ESA inspection are required for new wiring. If your heated mirror is a plug-in model (some are), it simply plugs into an existing GFCI-protected bathroom outlet, which a homeowner can do without an electrician.

Cost and Options in the GTA

Heated mirrors range widely in price depending on features. A basic heated mirror (LED-lit perimeter with built-in defogger) runs $200–$600 at GTA bathroom suppliers. Smart mirrors with integrated LED lighting, defogger, touch controls, Bluetooth speakers, and colour temperature adjustment run $500–$2,000+. Installation by a licensed electrician adds $150–$400 depending on whether new wiring needs to be run or the mirror can connect to existing wiring at the mirror location.

For GTA homeowners doing a full bathroom renovation, the most cost-effective approach is to plan the heated mirror wiring during the electrical rough-in stage — your electrician can run a dedicated wire to the mirror location and connect it to the vanity light switch or a separate switch at minimal additional cost. Retrofitting a hardwired heated mirror into a finished bathroom is more expensive because the electrician needs to fish wire through closed walls.

One practical consideration for Toronto condo bathrooms: many condo bathrooms have a single electrical box behind the existing mirror/medicine cabinet location. A skilled electrician can often tap into this existing box to power a heated mirror without running new wire, keeping the installation simple and affordable. Confirm the existing circuit capacity with your electrician before adding any load.