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I had a 60 amp breaker that was connected to an oven in the kitchen. Since this is no longer needed, I'm trying to re-purpose this #6 wire to connect to a new Electric water heater I'm putting in the basement. Putting any new wires will require me to break up the basement ceilings which I'd avoid if possible. So, I decided to put up a sub panel in the basement (about 15 feet from the main panel) and connect this 60 amp 6 gauge wire to the subpanel and add a 30 amp breaker connected to 10/3 wire to the new heat pump/water heater (35 ft away in the basement). But the original #6 wire only had a 2 hot and a neutral coming into the sub panel, no separate ground wire included. This house was built in the 80's and probably these wiring were done around the same time.

So, my question is this... how do I take care of the ground in the subpanel. The new electric water heater only takes 2 hot and a ground connection (no neutral needed). But, I'm only getting the neutral(and 2 hots) from the main panel and I don't really have anything to ground it to in the basement where this sub panel will be located. Is it mandatory to ground the subpanel separately? What's my best option here?

Thanks!

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  • Not clear - where is the hot water heater in relation to the range wiring? Is the range #6 wire white insulation?
    – batsplatsterson
    Commented Mar 13, 2019 at 19:39
  • Is the existing wire in metal conduit?
    – manassehkatz-Moving 2 Codidact
    Commented Mar 13, 2019 at 20:15

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Retrofit ground. Bada-bing.

Code specifically allows you to retrofit ground in a case like this.

Given that it's a 60A subpanel, you need to get a #10 ground wire between the subpanel's ground bar and the main panel's ground bar (which may also be its neutral bar, since neutral and ground bars are to be bonded in a main panel). As you probably know, in the subpanel you must keep neutral and ground fastidiously separate.

The ground wire may follow any reasonable path. It may be legal to route to the grounding electrode system or another branch circuit's #10 ground wire instead, but I recommend going to the panel because this is a subpanel.

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  • Thank you Harper! Got it. Follow up question though.. running the #10 wire back to the main panel for the ground will require me to break the basement ceiling too :-). could I potentially connect the ground from the sub panel to A/C wires ground line which is running nearby?
    – GreenwichDIYer
    Commented Mar 13, 2019 at 21:41
  • @GreenwichDIYer what gauge is that ground wire for the A/C?
    – ThreePhaseEel
    Commented Mar 13, 2019 at 22:59
  • looks like an 8 gauge.
    – GreenwichDIYer
    Commented Mar 13, 2019 at 23:08
  • If the AC has a 10 or larger ground it would be ok by the 2017 code as long as they are both fed from the same panel.
    – Ed Beal
    Commented Mar 13, 2019 at 23:29

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