Components of an Water Heater Circuit

Question: We are installing a new electric water heater, in a home addition. We have a sub panel, installed by the electrician who started the project, with the breaker ready to go. All we need to do to complete the job is to run the wire, and put in the shut-off switch near the water heater.

It seems that we will need 10 awg wire. (correct?)

My questions are:

Do we just run regular 10awg wire in the ceiling, and then as we drop down the wall in the unfinished basement, we put it into PVC or metal conduit?

I understand that the water heater needs a shutoff on the circuit near the heater.

My big question is, how do we terminate this wiring in prep for the water heater? We will probably have a plumber install the heater (because they are heavy!) although all the plumbing is ready to go, so it will be quick. I am not clear on what we need to leave the plumber in order for him to hook up the heater when he arrives. Do we just wire to the switch, and then the heater comes with wire to the other side of the switch? Or do we need to provide wire to the heater too?

This will be inspected, and we are working under a permit.

Thank you!

This electrical question came from: Cheri, a Homeowner from Wichita, Kansas.
See more about Home Wiring for Kansas

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

Water Heater Circuit Wiring

Cheri, a typical electric water heater requires a 30 amp 240 volt circuit. This circuit is generally provided by installing a 10/2 NM with ground cable to the location of the water heater. If the location of the water heater requires a disconnect then a 240 volt 30 amp rated switch or disconnect should be installed at the water heater location.

If the circuit wiring will transition to surface wiring then the cable can either have the outside sheath removed where it may be sleeved into a protective PVC or EMT conduit where the wire is protected from damage and the conduit is attached to the surface as required.

The circuit wiring is then typically attached to the water heater junction box using a supported flexible conduit and approved fittings as required.
Consult your water heater installation manual for specific requirements, and your local building department for specific codes for your area and project application.

The Following links will assist you with your electrical question:

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