Considerations on how to install baseboard heaters. Includes electric baseboard heater wiring-three different wiring scenarios and connections for electric baseboard heaters, single pole, and double pole wall-mounted thermostats, 240-volt versus 120-volt heaters.
DIY Electric Baseboard Heaters: How to Install Baseboard Heaters
Learn how to install baseboard heaters for supplemental or primary heating. See how to make the wiring connections at the wall-mounted thermostat and at the baseboard heater, work safely with the electrical wiring, and some considerations for installing your electric baseboard heater.
Electric Baseboard Heaters
Baseboard heaters offer affordable, supplemental heating for rooms that may not get enough heat from a home’s furnace. They can also provide the primary source of heating for additions or seasonal rooms which do not have access to the home’s heating system.
Energy efficient electric baseboard heaters may operate on either 120 or 240 volts. 240-volt heaters use less current to produce the same amount of heat as the same wattage 120-volt heater. This allows wiring with a smaller gauge wire which is both cheaper and easier to install.
Consider the following when determining how to install an electric heater.
- Size the circuit correctly using the right gauge wire and circuit breaker.
- The best location for a baseboard heater is under a window.
- The best thermostat location is on the wall opposite the heater.
- Never install a baseboard heater below an outlet.
- Mount the baseboard heater at least 12 inches away from flammable materials such as furniture, or drapery. Most allow mounting on top of carpeting.
Turn off the baseboard heater circuit breaker. Test to make sure the circuit is off with a non-contact voltage tester. Turn the tester on and bring the probe near the wires.
If the light stays off or the beeper does not sound, the wires carry no current and are safe to work on. Test all the wires, not just one.
Connecting the Wires: How to Wire Electric Baseboard Heaters
Nearly all baseboard heater installations will require connecting stranded wires in the heater and thermostat with solid wires between the thermostat wiring box and the baseboard heater, and also to the solid wires that connect to the service panel and circuit breaker.
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The diagram on the left illustrates two typical wiring scenarios for baseboard heaters with wall-mounted single pole thermostats. Single pole thermostats may be used with either 120-volt or 240-volt heaters while double pole thermostats only control 240-volt heaters.
Four Wire Single Pole Thermostat Wiring
One set of wires enters the thermostat wiring box from the service panel, the other set leaves the box and goes to the baseboard heater.
In most cases, each set has a black wire and a white wire but it won’t matter if the wires are all the same color or different colors. Select the two white wires or one colored wire from each set of wires and join them together (how to join solid wires) with a wiring nut.
Join each of the remaining wires (how to join solid wires to stranded wires) in the thermostat wiring box with one of the thermostat wires.
In the baseboard heater, join each of the two heater wires with one of the wires that run to the thermostat. It does not matter which wire connects to the colored wire or the white wire.
Two-Wire Single Pole Thermostat Wiring
The two wires in the thermostat wiring box run between the thermostat and the baseboard heater. Connect each wire in the wiring box with one wire from the thermostat.
In the baseboard heater, connect the black supply wire (the wire from the service panel) to the black wire that runs to the thermostat.
Connect the white wire from the thermostat to one of the baseboard heater wires. Connect the other wire from the baseboard heater to the white wire that runs back to the service panel.
Four Wire Double Pole Thermostat Wiring
Two wires on the thermostat are labeled “Line” and two are labeled “Load“. The wires labeled “Line” connect to the two wires from the double pole circuit breaker (a breaker with two switches). The “Load” wires connect to the two wires leading to the baseboard heater.
The baseboard heater’s metal case must be grounded. Inside the case is a green ground wire or a green terminal screw. Connect the green ground wire to the bare ground wire included with the sheathed cable.
If your baseboard heater wires were run through a metal conduit, the ground connection is the metal conduit.
Mount the heater to the wall with screws and the thermostat to the wiring box. Turn on the circuit breaker and turn the thermostat up higher than the ambient room temperature to test the new heater. That’s a how-to install baseboard heaters.