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So I was on a maintenance call for a building. A string of 3 plugs were off and it's a huge building and I couldn't locate the breaker after 2 hours searching. I went with the building owner inspecting every single panel and gfci plug to test if that was the issue. We couldn't locate the breaker or power source for those plugs. So I gave up looking for the breaker and did the following instead. There was a baseboard heater on a 20 amp circuit nearby. I tapped off one of the hots from that circuit with a 12/2 wire rated for 20 amps. There is no neutral so I left one wire capped off in that box. The other end I replaced with a 20 amp receptacle. I took off the hot wire I identified as the home run wire going to the panel and replaced it with the hot wire I spliced from one of the hots of the baseboard. I kept the neutral wire from the home run cable as I needed that neutral to complete the circuit. So now all the plugs work.

Just wondering if there is any fire issues or nuisance tripping this will cause down the line? It's been 2 months and the client hasn't called to complain.

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You cannot and must not take a phase from one cable/circuit and a neutral from another.

Amongst other issues, this:

  • Poses a threat to any maintenance worker who disconnects the neutral or earth of the original circuit, assuming that because they have isolated the hot, the neutral is not carrying current.

  • Can overload the neutral, which does not directly have overcurrent protection.

  • Can cause issues and heating in surrounding steel as the magnetic fields do not cancel.

  • Will cause immediate tripping if either circuit is converted to GFCI in future.

  • Violates the NEC/CEC/any other sensible rules.

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What about that neutral you poached? It is now returning current for two hots. It can get what, 20A from its normal circuit, and an additional 20A from the circuit you cross-wired. That's 40A on a neutral rated for 20A. Neutrals don't have breakers.

Honestly this is such a bad practice that bootlegging ground would have been less bad.

However it's more troubling that this has been continued in service for any time. It's one thing to rig a connection to get the bilge pumps running to keep the ship from sinking. It's quite another to leave that in service for months. You need to go back and fix that properly now that the time pressure is off.

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