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My well is powered by a 240V 30A circuit, the only circuit to the well house and the expansion tank and pressure switch. I want to winterize the lines in the well house with a heat tape, but the only way to get a 120V circuit is to tap off one leg of the 240V circuit and use a common neutral. I am well aware that this violates recent(?) NEC codes, but short of digging a trench for a new 120V circuit, don't see an alternative. Is this just messy, or dangerous, and if so, why?

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  • What about 240V heat tape?
    – Chris O
    Commented Feb 1, 2023 at 19:29
  • how much will you be drawing on the 120 V
    – Traveler
    Commented Feb 1, 2023 at 19:37
  • 240V heat tape is readily available, just not on the end-cap at the big-box store in a pretty package with a UPC code. It's hardwired, and it's a bit more DIY. Commented Feb 1, 2023 at 19:45
  • The 240V heat tape seems to be the consensus solution. Thanks!
    – AKG
    Commented Feb 3, 2023 at 1:31

4 Answers 4

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Two obvious solutions that should be legal.

240V->120V transformer. Now you have a "separately derived service" for 120V.

240V heat tape (shop the internet since Homely Despot won't have it.) While you are at it, get the good stuff that's "self regulating" and does not have a crappy thermostat to weld closed or fail to connect. The whole cable is the thermostat. It's much more reliable. And only the cold parts turn on.

Either one will probably require a sub-panel in the well-house so that the breaker feeding the heat tape or transformer is not the same size as the well pump breaker, unless the well pump breaker is quite small as well pumps go (15 or 20A at most) - which it's not.

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  • It would have to be a very particular transformer. The el-crappo red or black 'step down transformers' off Amazon Marketplace are totally the wrong thing. A 1.5 kVA 120/240V isolating transformer would be ideal since that would let you run power tools and a bouncy castle or whatever out there too. However a smaller one would also suffice as long as it is isolating. Commented Feb 1, 2023 at 19:48
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Any solution must be hard-wired because of NEC requirements.

240V heat tape from better suppliers is probably your answer.

I don't know how your well house is laid out, but another option is to put a space heater out there. It's no problem getting 240V space heaters, they're sold by Cadet as baseboard units as small as 375 watts, and are well under $50. External thermostats are $15-ish and wire in like a light switch.

However other than that, you can obtain 240V heat tape from better suppliers. McMaster-Carr sells it for $9/foot and they're not the cheapest in town by any stretch.

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  • The 240V heat tape seems to be the consensus solution. Thanks!
    – AKG
    Commented Feb 3, 2023 at 1:30
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If The pump circuit is straight 240 Volt, two 120 Volt legs, with ground then no, you can't do it. There's no neutral and you can't utilize a ground for it. If a neutral was run with the circuit, you could add a small sub panel with a double pole breaker for the pump and a single breaker for the heat tape. Most of us won't give an answer to a solution that violates the code.

You might try some solar applications out there if the load for the tape is low.

Added information: @Harper's comment states 240V heat tape is available. Would still need sub panel.

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  • The 240V heat tape seems to be the consensus solution. Thanks!
    – AKG
    Commented Feb 3, 2023 at 1:31
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The 240V heat tape seems to be the consensus solution. Thanks to everyone who suggested it. I will have to check wattage for both pump and heat tape, but I believe the total wattage is going to be supplied by the 30A circuit.

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