How To Wire A BaseBoard Heater - Conquerall Electrical

How To Wire A BaseBoard Heater


Understanding how a heater works can be difficult. We will help you through the process on how to wire a baseboard heater. Sizing it the key to the process.

Most heaters have wire nuts inside one end of the connection box to make the termination. Connecting L1 and L2 to the heater is a simple process. Make sure the ground wire is connected to the back of the heater.

Safety First On How To Wire A Baseboard Heater

The most important thing when you’re talking about wiring a baseboard heater is always your safety first. Make sure you shut the power off at the panel before you do anything.

If you have a voltmeter then it is a good idea to use it .

You always want to be certain 100% certain that the power shut off.

Shutting Off The Power On How To Wire A Baseboard Heater

how to wire a baseboard heater

Look at the panel look for the circuit marked heater and shut it off. It will most likely be a double pole 20 amp circuit.

Before you install the new heater take your voltmeter and make sure it is on 240 volt or 300 volt reading.

You can test from the red to the black wire and you should get 240 volt with the thermostat on. This is done before you shut the power off.

You can also test from the red to the ground which is the bare copper wire and you should show 120 volt.

Test from the black to the ground and you should show 120 volt.

It’s also just the opposite when the power shut off you should get 0 V across all three.

Sizing The Heater For The Room

There are several different size heaters that you can install in a room. As a rule of thumb we use 10 W per square foot.

So for example if the room is 10 x 10 or 100 ft.² you would multiply that by 10 watts per square foot. This equals out to be a 1000 watt baseboard heater.

To make things simple just multiply your square footage by 10.

150 square-foot room would be a 1500 W heater.

200 square foot room would be 200 watts etc.

What Type Of Heater Should I Buy?

When making a purchase on a regular baseboard heater it is always a good idea to check the room sizing like mentioned above.

Replace the heater with the same physical size that was there before. You will want to do this so you do not have to make repairs to the baseboard itself.

For more on what we recommend for heater types you can find that out here.

how to wire a baseboard heater

How Long Are The Different Size Heaters?

Electric baseboard heaters come in a variety of shapes and sizes depending on your application.

We have included a chart below to show you the various links for a standard baseboard heater.

These are the type of baseboard heaters that you see in your local hardware store. Stelpro

500 watt27 7/8 inches
750 watt37 5/8 inches
1000 watt47 1/2 inches
1250 watt57 1/4 inches
1500 watt66 1/4 inches
1750 watt76 inches
2000 watt83 /7/8 inches
2250 watt93 3/4 inches
2500 watt102 5/8 inches

What About Those Space Saver Heaters?


A few years ago some companies decided to come out with a baseboard style heater to shorten its length.

As a comparison a regular baseboard heater of 1000 watt is 4 feet in length and a space saver 1000 watt is only 2 feet in length.

If you decide to purchase the shorter length save saver heaters please make sure you use the stand off wall kit included.

This wall kit protects the wall itself from heating up. It makes the heater stick about half inch off the wall.

You can find out more where to purchase these heaters here.

What Color Wire Do I Need?

how to wire a baseboard heater

The standard wire color for a baseboard heater is red. This type of wire is referred to as nmd90 12/2 non metallic dry.

We use this type of wire in dry locations usually wood construction type.

There are some instances where we do use this type of cable in commercial projects providing it is of wood construction.

How Do I Connect The Heater To The Wire?

Connecting the wires to the baseboard heater is actually quite easy.

You’ll come into the back of the heater through the terminal provided. You will then simply wrap the bare copper ground wire around the screw.

You then terminate the red and black wires with a pair of wire nuts.

Make sure you do not over tighten the clamp on the back of the baseboard heater. This will cause the wire to short out.

The red wires will terminate together and the same with the black wires.

In most standard baseboard heaters you can enter on ether side with the wire.

After the connections are made, screw the heater to the wall and install the cover plates.

The cover plates can be a bit tricky. They usually go on bottom side first then push the top into place.

Can I Wire A Baseboard heater To An Electrical Outlet ?

It is not recommended to wire a baseboard directly to a wall outlet. You would need a 120 volt special order baseboard. This would be the only time it would be permitted.

The other issue is most 120 volt baseboards can consume an entire 15 amp circuit.

This would not leave amperage left over to use for the outlet itself.

If you are going to use an electrical outlet, it should be a plug in portable heater.

How To Wire A Baseboard Heater On The Left Side

There are some baseboard heaters that you can wire on the left side.

Most standard heaters you purchase will allow for both sides of entry with the wire.

One of the key factors when picking a side it to check the other side of the heater that you don’t use.

The connections on the other side should be wire nutted together to complete the circuit.

If you do not close the other end of the loop the heater will not work as it will not complete the circuit.

Note that some electrical heaters do not allow a left side wire entry. Just make sure you check that when making a purchase.

Does A Baseboard Heater Need To Be A Dedicated Circuit?

Yes, all electric baseboard heater should be on a dedicated circuit. It should be clearly marked at the source or panel as to what its for.

This applies for several baseboard heaters on the same circuit.

On a 240 volt circuit you can install 3840 watts of heaters.

You should never try to install a heater with lights or other appliances.

How Do You Wire Multiple Baseboard Heaters?

When wiring multiple baseboard heater be careful of circuit loading. Do not exceed 80 percent of the circuits capacity. The wires themselves usually run from heater to heater.

We call this daisy chaining. The wire comes from the wall thermostat to the first heater. Then from the first to the second and so on.

Again be careful of fastening the wires under the clamp on the back of the heater so you do not over tighten.

We recommend installing the wires into the clamp on the back of the heater before you strip the wires.

All of the images used in the article are stelpro. We are a distributor and supplier of this product.

You can find more on baseboard heaters here.

More on what we recommend for heating products here.

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