ask the electrician
Electrician Training Electrical Certification wiring recessed light fixtures Electrical Wiring Electrical Troubleshooting and Electrical Repairs wire outdoor light fixture Home Electrical Wiring Diagrams
wiring home generator and transfer switch wiring a 220 volt range cord outlet Wiring for GFCI Outlets Wiring Outlets and a Switched Outlet Wiring and Installing Ceiling Fans and Remote Controls wire dimmer switch wiring diagrams for switches wiring a dryer cord and 220 outlet circuit breaker panel
Electrical Wire and Cable

Electrical Question from Martin about 240 Volt Wall Heater Wiring

Will 12-2 wire and a 20 amp breaker handle a 4000 watt 240 volt wall heater?

© By:

Electrical Wiring Video

Home Electrical Wiring Videos about this Topic and More

Check out my YouTube Channel, and Subscribe!

Learn more with my Home Electrical Video Course:

Basic Home Electrical Wiring by Example

Electrical Question from Martin about 240 Volt Wall Heater Wiring

Received from Martin a Homeowner in Tacoma, WA

[ad#block]Question: Will 12-2 wire and a 20 amp breaker handle a 4000 watt 240 volt wall heater?

Dave’s Reply:
Thanks for your electrical question.
Hi Martin – A 4000 watt 240 volt wall heater will require about 16.6 amps. Although a 12/2 wire is rated at 20 amps it would be best to install a 10/2 wire for a 4000 watt 240 volt heating unit. This would ensure that the circuit is safely loaded at 80 % of the capacity of the wire.
When using a 2-wire Romex cable with a ground understand that a 2-pole circuit breaker will be required and the white wire will need to be identified with red or black electrical tape as a power conductor at both ends of the circuit.

The Following links will assist you with your electrical question:

For more information about Electrical Wiring
Electrical Wiring

This link is helpful as a Homeowner
Do-It-Yourself Electrical

Make sure not to miss these Resources for: How-To-Videos
Electrical Videos

Be Careful and Be Safe – Never Work on Energized Circuits!

For Best Results Consult a Licensed Electrical Contractor.
Locate An Electrical Contractor in Your Area

The following may also be helpful for you:

electrical wiring book

A Complete Guide to Home Electrical Wiring

Be sure to get your copy of my BIG Book:
Perfect for Homeowners, Students and Electricians
Home Electrical Wiring - Room by Room
120 Volt Circuits
240 Volt Circuits
Multi-Wired Circuits
Wiring Methods for Installing Home Electrical Circuit Wiring
Electrical Codes for Home Electrical Wiring
....and much more.

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

More articles about 220 Volt Wiring, Electric, Heater and Home Electrical Wiring:

« Previous Next »

Electrical Question from Ryan about The Vented Toilet Seat

Electrical Question from Sankar about Sizing Cable for a MCCB

FAQs Frequently Asked Questions and Comments

4 Responses to “Electrical Question from Martin about 240 Volt Wall Heater Wiring”
  1. Dave Rongey says:

    Wire Size for a Water Heater
    Hi Del,
    240 volt Water heaters come in several different sizes, therefore it is essential to identify the specific water heater you have before determining the wire size.
    Please Note: The wire size is based on the amperage or watts, as well as the voltage.
    I hope this helps,

  2. Del says:

    Water Heater Wire
    Will 10-2 Romex work with a 240 volt water heater?

  3. Dave Rongey says:

    Hi TJ
    Here is the confusion:
    This type of 240 volt circuit for this wall heater does not require a 3-wire (with ground) cable, so 99% of the time there would be a 2-wire (with ground) cable installed, which would not have a red wire. So in the case of a 2-wire cable the white is colored red.

    In a case like yours where there is a 3-wire cable, I would normally cap off the white wire as a spare, and connect black/black, red/red ground/ground as instructed.
    HOWEVER – this may only be done if it can be verified that the black and the red are in fact terminated at the 2-pole circuit breaker for the 240 volts, and it normally is, you just want to be sure.
    If the white wire of the 3-wire cable is terminated to the neutral buss then that may remain as it is, just make sure it is capped off at the heater end.
    Also verify that the ground wire is terminated to the ground buss.
    And that’s it – you will be set.
    Enjoy the heat and Be Careful!

  4. TJ says:

    I have a Fahrenheat 240 volt wall heater,
    10/3 romex (Black, red, white and bare)
    The heater has 2 wires and the ground nut (green) on the back box.
    Black to black, bare ground to the ground nut on the back box,
    instructions (and code) says white gets changed to black (electrical tape),
    doesn’t say connected to what?
    what happens with the red as i thought that was the other hot leg?