How to Wire a Baseboard Heater to a Thermostat

How to Wire a Baseboard Heater to a Thermostat

Electric baseboard heaters in Ontario are typically 240V units wired on a dedicated circuit. The thermostat can be either a line-voltage thermostat (wired directly in the circuit) or a low-voltage thermostat (used with a relay). Most residential baseboard heaters use a line-voltage thermostat rated for 240V — do not use a standard 24V HVAC thermostat on a baseboard heater circuit without a compatible relay, as it will not function correctly and may be a fire hazard.

Line-Voltage Thermostat Wiring (240V)

• Turn off the circuit breaker for the heater circuit and verify with a non-contact tester before touching any wires
• A 240V baseboard heater circuit has two hot conductors (typically red and black) and a bare or green ground — there is no neutral in most 240V heater circuits
• The line-voltage thermostat is wired in series with the heater: the two incoming hot conductors from the panel connect to the thermostat line terminals; the two outgoing conductors from the thermostat connect to the heater load terminals
• The thermostat must be rated for the heater’s wattage — a 2000W heater draws about 8.3A at 240V; the thermostat must be rated for at least that amperage
• Ground the thermostat enclosure if a grounding terminal is provided

Important Notes for Ontario

Installing a new baseboard heater circuit or moving a thermostat to a different location requires an ESA permit in Ontario. Replacing an existing thermostat in-kind on an existing circuit is typically maintenance work, but if any wiring is extended or a new circuit is run, a permit is required. EZSMART installs and replaces baseboard heater circuits and thermostats across Ontario and handles all permit coordination with the Electrical Safety Authority.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp