This article will you understand the wire sizes and what size wire for a baseboard heater.
In total a standard 12 gauge awg should be used for wiring electrical heat circuits. This is used for residential and commercial applications. Always refer to the electrical code for wire sizes. Most all baseboard heaters require 12 gauge as it is reliability available.
1.Chart For What Size Wire For A Baseboard Heater 240 Volt
| 500 watt | 240 v | 2.08 A | 12 Gauge |
| 750 watt | 240 v | 3.12 A | 12 Gauge |
| 1000 watt | 240 v | 4.16 A | 12 Gauge |
| 1250 watt | 240 v | 5.20 A | 12 Gauge |
| 1500 watt | 240 v | 6.25 A | 12 Gauge |
| 1750 watt | 240 v | 7.29 A | 12 Gauge |
| 2000 watt | 240 v | 8.33 A | 12 Gauge |
| 2500 watt | 240 v | 10.41 A | 12 Gauge |
| 3000 watt | 240 v | 12.5 A | 12 Gauge |
| 4000 watt | 240 v | 16.6 A | 10 Gauge |
| 5000 watt | 240 v | 20.8 A | 10 Gauge |
| 6000 watt | 240 v | 25 A | 8 Gauge |
| 8000 watt | 240 v | 33.3A | 6 Gauge |
| 10000 watt | 240 v | 41.6 A | 6 Gauge |
When it comes to wiring the baseboard heater in terms of wire size standard application is used 12 gauge NMD 90.
You will notice that most of the amps are below 20 amp which is what 12 gauge is rated for.
Technically yes you could use 14 gauge if you were to wire only one heater.
This is the red wire that you will see your hardware store or supplier. It has a red and black wire inside as well a bare ground.
This is what we use for a typical installation.
You should never load the circuit up some more than 80% of the rating of the breaker or wire for 20 amp. You can only load the circuit up to 16 amps which is actually 3840 watts of electricity.
2.Chart For What Size Wire For A Baseboard Heater 120 volt
| 120 v | 3000 watt | 25 amps | 8 gauge |
| 120 v | 2000 watt | 16.6 amp | 10 gauge |
| 120 v | 1500 watt | 12.5 amp | 14 gauge |
| 120 v | 1000 watt | 8.3 amp | 14 gauge |
| 120 v | 750 watt | 6.25 amp | 14 gauge |
| 120 v | 500 watt | 4.16 amp | 14 gauge |
| 120 v | 300 watt | 2.5 amps | 14 gauge |
| 120 v | 150 watt | 1.25 amps | 14 gauge |
You will notice in the diagram above that the 3000 watt heater is rated at 10 gauge an it is because of that 80 percent circuit loading rule.
Because it is 25 amps instead of 24 you have to go up a size in wire.
Wiring a 120 V heater can be a little different as some units just plug straight into the wall.
As a rule of thumb you can safely go up to 1500 W on an electrical outlet.
We often use 120 V heaters when we do not have 240 V available. You can order 120 V baseboard heaters but you will be hard-pressed to get one over 1500 Watt in size.
3.What Other Wire Sizes Are There For Base Board Heaters?
As mentioned above the standard size wiring for a baseboard heater is 12 gauge. You can get into larger size permanently mounted heaters that are hardwired into the home.
You will also notice in the tables above that when you double the voltage you will cut the amps in half.
For example a central air system can we require as high as 100 Amp for the electric heat bank.
Some garage heaters that can mount on the baseboard can consume up to to 50 amp.
This is usually plugged in with a standard welding receptacle.
4.What Kind Of Wire Do I Need For A Baseboard Heater?
If you are installing a baseboard heater in a drywall wood frame constructed area. You can simply run the NMD non-metallic type dry wire.
This will need to be mechanically protected below 1.5 m or 5 feet.
If the wire runs on the surface then you may be better off to run AC 90 or armored cable as we refer to it.
Most baseboard heaters come with a half inch knockout in the side so that you can terminate the AC 90 into the heater.
5.Does The Location Of The Heater Matter For What Kind Of Wire?
As mentioned above it does matter the type of wire that you run for the location.
If you were in a damp or wet location and it is recommended that you use tech conductor and or a flexible protected conduit.
The only time you should be using NMD nonmetallic dry wire is when the wire will be enclosed in a wall.
If you are installing a baseboard heater in a drywall wood frame constructed area then you can simply run the NMD non-metallic type dry wire.
This will need to be mechanically protected below 1.5 m or 5 feet.
If the wire runs on the surface then you may be better off to run AC 90 or armored cable as we refer to it.
Most baseboard heaters come with a half inch knockout in the side so that you can terminate the AC 90 into the heater.
6.Does The Size Wire Change If I Hook Up More Than One Heater?
When running a bunch of heaters in parallel. It is recommended that you had the wire size goes up.
As mentioned in this post and other posts you can go to 16 A on a 20 amp circuit.
24 A on a 30 amp circuit safe to convert that to watch you would simply take your voltage time your amperage which equals watts.
You can see 3840 Watts on a 20 amp circuit. This can be a number of heaters that you hook into the circuit to equal to 3840 watt.
This is called maxing out the circuit and we often do this in new home construction to save them wire prices.
7.What Size Breaker Does The Wire Need To Be On?
Typically you will need to have the wire connected to a 20 amp breaker.
This type of breaker is referred to as a double pole 20 amp. It is also what is used for 12 gauge wire.
If you are mounting a single heater and you are using 14 gauge then the max size you can install for a breaker is 15 amp double pole.
In no case should you install and undersized wire.
8.Is This The Same If Its On A Fuse
Fuse ratings are the same as a breaker. If you are install 12 gauge heatex then it should be protected by two 20 amp fuses.
You will need two fuses to created the proper voltage or 240 volt in this case.
Fuse bocks are specific to 120 or 240 volt so make sure you get the right one.
The 240 volt fuse block will have a pull out tab in the middle of it.
This is so it makes it easier to pull out of it’s holder in the fuse box.
9.What Happens If The Wire Is Too Small For The Heater?
If the wire is too small for the heater then it will simply blow the fuse or trip the breaker.
This is providing you have the fuse or breaker size correct.
If you don’t have it sized correctly and get yourself into an oversized fuse situation. You can burn the wire up and most likely cause a fire.
Allowing more amps to flow through a wire than it is rated for it a no no.
That it where the heat is caused from in the wire and melts.
Over fusing is a common problem with fuse panels. A lot of people thing oh I’ll just put a bigger fuse in to giver me more power so it doesn’t pop.
Big mistake. You are allowing more amps to flow through the wire than it is designed for.
This is why so many homeowners insurance policies push to have fuse panels removed in the home. More on fuse panels here
10.Wiring Baseboard Heaters In Parallel
Wiring baseboard heaters in parallel is when you will get into the importance of amps and not exceeding them. It is important not to go over the 80 percent circuit rating.
So if you are adding heaters up around a room try not to install more than 3840 watts or 16 amps of the 20 amp circuit.
The rule applies to all types of wire sizes. For example a 30 amp circuit would be 24 amps. 24 amps multiplied by 240 volt is a maximum of 6000 watts loaded on the circuit.
The images in this article were used as we are certified Stelpro installers and dealers.
You can find more on heating products here.