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Electric Water Heater Wiring

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How to Wire a 240 Volt Water Heater Circuit:Common Wiring Methods for an Electric Water Heater, Basic Water Heater Circuit Requirements, Connect Water Heater Wiring

Guide to Wiring an Electric Water Heater

Electrical Question: I’m wiring a electrical hot water tank.

  • I have a 50 Amp wire to it out of the box is a white red and black and copper ground.
  • Out of the hot water tank is only a red and black.
  • Where does the white wire from the house hook up to?

This electrical wiring question came from: Nate, a Homeowner from Whittaker, Michigan.

Dave’s Reply:
Thanks for your electrical question Nate.

How to Wire a 240 Volt Water Heater Circuit

Application: Wiring a 240 Volt Electric Water Heater.
Skill Level: Intermediate to Advanced, Best installed by a Licensed Electrical Contractor. Work in electrical panels is not recommended for homeowners, non-experienced individuals or non-electricians.
Tools Required: Basic Electricians Pouch Hand Tools, electric drill, auger bits and extension cord as needed depending on the scope of the project.
Estimated Time: Depends on personal level experience, ability to work with tools and install 240 volt electrical circuit wiring.
Precaution: Identify the main circuit of the panel, turn it OFF and Tag it with a Note before working with the wiring or installing the 240 volt wiring and circuit breaker.
Notice: Installing an additional 240 volt circuit should be done according to local and national electrical codes with a permit and be inspected.

Common Wiring Methods for an Electric Water Heater

  • Basic Water Heater Circuit Requirements

    • An conventional 240 volt electric water requires a dedicated circuit.
    • The the typical circuit is a 30 amp 240 volt dedicated circuit.
    • The circuit cable wiring includes two insulated wires designated as Line-1, Line-2 and the ground conductor.
  • Does a Water Heater Require a Neutral Wire?

    • At this time, the conventional hot water heater does not require a neutral, however that will most likely change.
    • Neutral wires are required for other 220volt and 240 volt appliances that have electronic controlsĀ  that require a dedicated neutral, which is included with the 4wire cord.
    • If the circuit wiring is supplied by a 4-wire cable, and there is a spare white wire then simply cap off the white wire with a wire connector fastened onto the end of the wire.
  • Connect Water Heater Wires

    • It is a very common practice to install a 10/2 Cable with a Ground Wire.
    • The 10/2 cable actually has 3 wires including the ground wire.
    • With this type of cable wiring method, the black and white wires are used for the 240 volt circuit, so the white wire is colored typically with either red or black electrical tape or a permanent marker.
    • A conventional electric water heater will come with a black wire and a red wire which are connected to the wires of the same color as described above. The ground wire is attached to the green ground screw which is in the same wiring junction box compartment which is built into the top of the water heater.
  • Protecting the Circuit from Overload Conditions

    • Never use a cable that is too small for the water heater circuit, and be sure the circuit breaker is sized correctly for the circuit. Typically with #10 gauge copper wire a 2-pole 30 amp 240 volt circuit breaker is installed.
    • If existing circuit wiring will be used for the water heater and the circuit is larger then the circuit breaker should be replaced with a 30 amp breaker. The rule of thumb is to size the circuit breaker for the smallest size wire type within the circuit, or as indicated on the equipment label or as instructed in the installation manual.

The Following links will assist you with 220VoltĀ  and 240Volt Water Heater Wiring
220 Volt Appliance Wiring Requirements
See how some 220 volt appliances do not use a white common wire, instead they use two hots and a ground.

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


3 Responses to “Electric Water Heater Wiring”
  1. chris sterup says:

    I have a hot water heater that I want to remove and replace the wiring with an outlet to utilize the dedicated circuit. Is this doable for someone who’s pretty handy, or do I need an electrician and how?

    • Dave Rongey says:

      Hi Chris,
      If you are referring to converting a 30 amp 220 volt circuit to be used as a 120 volt, then yes, this can be done fairly easy. Keep in mind that the circuit wiring will need to be converted to 120 volts at the electric panel, and a new circuit breaker must be installed and sized to the amperage of the receptacle that will be installed, which is typically 15 or 20 amps.
      Working in an electrical panel is not recommended for homeowners, so this is best performed by an electrician.

  2. raiford adams says:

    I have a Envi-ro-temp Energy Saver model 90a-1980 30 gal. single element 220 volt electric water heater and need to wire it in to my house.How do I wire it?

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