Electric Water Heater Wiring Connections

By Dave Rongey - Summary:

How are the electrical wires connected for an electric water heater? Wiring Connections for a 240 volt 30 amp Electric Water Heater.

Wiring a Water Heater

Electrical Question: How are the electrical wires connected for an electric water heater?

I want to install a new electric water heater on a double breaker – two pole 30 AMP circuit that previously fed an electric dryer which is now discarded.

  • The wire type is labeled 10-3 AWG copper.
  • The wire colors are black, red and white.
  • How should these wires be connected to the wiring on the water heater?

Thanks, Linus.
This water heater question came from: Linus, from Port Royal, Pennsylvania.

Dave’s Reply:
Thanks for your electric water heater question Linus.

How to Wire a Water Heater

Application: Wiring a 240 Volt Electric Water Heater.
Skill Level: Intermediate to Advanced – Best installed by a Licensed Electrical Contractor and Certified Electrician.
Tools Required: Basic Electricians Pouch Hand Tools, Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and install 240 volt electrical circuit wiring.
Precaution: Identify the water heater circuit in the panel, turn it OFF and Tag it with a Note before working with the wiring connections.
Notice: Installing an additional 240 volt water heater circuit should be done according to local and national electrical codes with a permit and be inspected.

  • Electric Water Heater Connections
    Linus, the typical electric water heater requires a dedicated 30 amp 240 volt circuit, and making use of the dryer circuit which is not used is OK to do, however as  you discovered the dryer circuit has a dedicated neutral wire which is not required for your electric water heater, so in a case such as this here are the connections:
  • Wiring Connections for a 240 volt 30 amp Electric Water Heater
    • The ground wire of the circuit is fastened to the provided green ground screw which is found in the wire connection junction box.
    • The white neutral wire is just capped off with a wire connector or electrical tape.
    • The Red Wire of the circuit connects to the red wire of the water heater.
    • The Black Wire of the circuit connects to the Black wire of the water heater.
  • Connecting the Wire of a Water Heater
    • If your water heater has two black lead wires it really does not matter which connection of the red wire and black wire connects to the water heater leads.
    • Support any flexible conduit and provide proper connection fittings.
    • Install the cover plate over the water heater wiring connection junction box.
    • As always, positively identify the circuit and make sure the circuit is off before making any connections, and be sure to relabel the circuit breaker to show that it is now being used for the water heater.
  • Install a Water Heater Time Clock Energy Savings Option
    • Consider installing a Water Heater Time Clock which will enable you to control the water heater so that it is not On all the time.
    • A suggested schedule would be to have it turn OFF at bedtime and turning back ON one hour before you normally get up. this will save a considerable amount of energy.

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