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  1. #1
    Join Date
    Feb 2011
    Posts
    2

    Default New Water Heater Wiring?? Couple quickies..

    Hello,

    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 pumbing 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!!

  2. #2
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,356

    Default Re: New Water Heater Wiring?? Couple quickies..

    You will need to provide the wire going to the water heater; for a 30A circuit (common for water heaters) you will need 10/2 w/ground Romex. (10/3 is not necessary.) If the sub-panel was installed properly, there will be a neutral bus and a separate grounding bus. Do not connect the ground wire to the neutral bus. If you're not sure which is which, the neutral bus should have a large white wire leading to it, and the grounding bus should have a bare or green wire.

    It doesn't really matter if the wire from the ceiling to the switch is in PVC or metal conduit, but if it's metal conduit it will need to connect to a metal box, and the ground wire in the 10/2+Ground cable will need to be connected to the box itself. Make sure the conduit is fastened to the wall. If using metal conduit, install a box fitting at the top with a plastic bushing screwed on the threads, to prevent the sharp edge of the conduit from piercing the insulation. Be sure to use a cutout switch rated for 30A.

    (In the switch box, use a large wire nut to connect the incoming ground, a lead to the box, a lead to the switch if it has a ground screw, and the wire to the water heater. All ground wires should be 10 gauge.)

    As for the wire to the water heater, use a piece of flexible conduit -- again, either metal or plastic is OK, just be sure to use the proper connectors -- from the switch box to the water heater. You'll probably want to have about 3 feet of flex conduit, and the wires should extend another foot (if too long, they can be shortened when installed).

    One more thing: since this is a 240V only circuit, if you use 10/2 romex, be sure to color the white wire at both ends either by wrapping it with black tape or coloring it with a permanent marker. This indicates that it's not a neutral wire, and it's required by code to mark it.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  3. #3
    Join Date
    Feb 2011
    Posts
    2

    Default Re: New Water Heater Wiring?? Couple quickies..

    PERFECT. Thank you! Exactly what I needed.

    Quote Originally Posted by Fencepost View Post
    You will need to provide the wire going to the water heater; for a 30A circuit (common for water heaters) you will need 10/2 w/ground Romex. (10/3 is not necessary.) If the sub-panel was installed properly, there will be a neutral bus and a separate grounding bus. Do not connect the ground wire to the neutral bus. If you're not sure which is which, the neutral bus should have a large white wire leading to it, and the grounding bus should have a bare or green wire.

    It doesn't really matter if the wire from the ceiling to the switch is in PVC or metal conduit, but if it's metal conduit it will need to connect to a metal box, and the ground wire in the 10/2+Ground cable will need to be connected to the box itself. Make sure the conduit is fastened to the wall. If using metal conduit, install a box fitting at the top with a plastic bushing screwed on the threads, to prevent the sharp edge of the conduit from piercing the insulation. Be sure to use a cutout switch rated for 30A.

    (In the switch box, use a large wire nut to connect the incoming ground, a lead to the box, a lead to the switch if it has a ground screw, and the wire to the water heater. All ground wires should be 10 gauge.)

    As for the wire to the water heater, use a piece of flexible conduit -- again, either metal or plastic is OK, just be sure to use the proper connectors -- from the switch box to the water heater. You'll probably want to have about 3 feet of flex conduit, and the wires should extend another foot (if too long, they can be shortened when installed).

    One more thing: since this is a 240V only circuit, if you use 10/2 romex, be sure to color the white wire at both ends either by wrapping it with black tape or coloring it with a permanent marker. This indicates that it's not a neutral wire, and it's required by code to mark it.

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