House came with an ncient water heater that struggled but worked well enough until a leak and some other issues caused me to burn out one or both elements. The labels in the box were wrong so I drained the tank and found everything was still live. Is it too difficult to throw on a 'has power' indicator light? Anyway.

Time to replace it. I turned off the double for the water heater and I'm still waiting to see what is turned off by it. I also found that a pair of single breakers that when either one were off showed that the lines to the water heater were no longer hot. What? That cannot be right and I'm sure there's some reasonable danger involved for not just hooking it up properly.

Is the obvious fix of putting it back on the double breaker labeled for it really that simple? Or in case its actually hooked up to something else, replacing those two singles with a double?

Someone with some brains tell me I'm not going crazy.

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    All I can figure is the double is bad and rather than get a new double, they moved things to 2 open singles. What is current rating of the singles? Not sure how they wired it to have it totally cut off power if only 1 single is off. How many conductors are coming into the water heater?
    – topshot
    Sep 23, 2016 at 20:13
  • The two singles that seem to run the water heater are each 30 amps. I have a cheap voltage tester that showed 220 or 240 from the two hot legs coming from the wall. I had someone holding the meter while I was flipping things on and off looking for the right one, so he probably only saw that between the two legs it was off or something. Even if one was still live, maybe. I dont know honestly. I flipped both off and didn't get shocked while I hooked up the new one. The kicker is the double labeled for the water heater does have something wired into it. Sep 23, 2016 at 20:26
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    I see. I didn't know two singles of the same amps was the same as a double. Considering some of the electrical problems I've had caused by poor choices of previous owners I was assuming the worst. As far as the double breaker, I assume it's probably running as a pair of conjoined singles to two different circuits and that's also acceptable? Sep 23, 2016 at 20:40
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    if the 2 breakers are side by side or on opposite legs (L1 / L2) there will be 240 available. There is a circuit called a multi wire branch circuit that uses the 2 hot 1 neutral and 1 ground to supply 2 circuits. This is legal and saves on wire for 15 & 20 amp branch circuits used in home wiring NEC 210.4. When checking your water heater don't only check across the hot legs check each one to ground since the handles are not properly tied. Installing a single double pole 30 amp breaker would be the safest way to power your water heater breakers are cheap.
    – Ed Beal
    Sep 23, 2016 at 20:59
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    I cant tell gauge by sight but 90% of the diy electrical I've done has been 12ga wire and the wiring to the water heater is definitely larger. I've yet to see what is turned off with that mislabeled breaker, but the two singles were labeled for a disposal and dishwasher (spoilers, the dishwasher works with them off) so that's something else I need put time into figuring out. I will put in a proper double just to avoid anything getting weird in the future. Sep 23, 2016 at 21:10

2 Answers 2


You can replace the two single pole breakers with a 30A double pole, or use an appropriately identified handle tie between the existing single pole breakers as well as per 240.15(B)(2) as typical electric storage water heaters don't have any 120V loads. Of course, this all requires the breakers to be adjacent.


You could add a disconnect in the same room as the water heater (which is code to have unless panel is in same room) for future use when servicing/replacing.

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