240V splits to 120V at well pump (safety concern)


Old 09-18-17, 02:10 AM
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240V splits to 120V at well pump (safety concern)

There are two old ~80 sq ft storage buildings on my parents property powered by the same circuit. One of them has a deep well jet pump.

The circuit starts at the main house's breaker panel as a 12-2 w/G on a 2-pole 20 amp breaker at 240V. The line is buried without protection at ~1' deep and runs for about 100' to the pump in the first storage building. The pump operates on two 'hot' wires at 240V and has the safety precaution of a dedicated ground wire (although the ground rod at the house is broken at the wire clamp). There is no wire leading back to the neutral bus in the circuit breaker.

Then the line is extended from the pump to power the 120V receptacles and lights in the two buildings. This was done by using another 12-2 w/G. Cutting and leaving the ground wire from this second cable unused, whoever wired these buildings connected the black wire to the black terminal on the pump (thus it shares the same feed) and connected the white wire to the ground screw on the pump (sharing the space with the ground wire that IS in use from the line that feeds the pump).

Therefore it seems the receptacles and lights in the storage buildings are using one of the 'hot' legs of the 240V circuit and using the ground wire as the return path. So any time a light was on in those buildings, the pump casing should have had a return load surging through it as it acted as the "neutral" line for the 120V circuit.

I don't know how this was overlooked and no one got electrocuted. Or is this even a safety concern at all since it should also be grounded through the well casing that is 90' deep?
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Old 09-18-17, 05:02 AM
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It is unsafe and against code. Use of the ground wire (equipment grounding conductor) as a neutral is a no-no.

You should immediately (shut off the power and) unhook the continuing line at the pump house..

As a stopgap you can unhook the far end of the continuing line and then reconnect the end at the pump house to both hot wires that feed the pump. The continuing circuit becomes a 240 volt only circuit. Put a band of black tape on both ends of the white wire of the continuing line.

At the far end connect a 240 to 120 volt step down transformer and you can power some low wattage LED lights.

There are other issues too. At that distance a 12 gauge line will give you only about 15 amps and with anything non-trivial running in the other building the voltage drop could shorten the life of the pump.

If you put in a subpanel at the pump house with 6 gauge copper (hot hot neutral & at least 8 gauge ground) line, (properly buried at 24 inches if direct bury cable or 18 inches if individual conductors in conduit) you will get about 40 amps at 240 volts, some of course consumed by the pump. When you do this you must immediately decommission the old line(s) although you could repurpose them for remote control of lights in the outbuildings.

Fix the ground rod connection. Also, all ground rods about any given building and used for anything including TV antennas need to be interconnected using 6 gauge copper wire run outdooes as much as possible e.g. along the foundation. .One 6 gauge connection goes from the main panel neutral/ground bus bar to the nearest ground rod.

Last edited by AllanJ; 09-18-17 at 05:59 AM.
Old 09-18-17, 08:19 AM
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I actually put a switch in a few months ago just before the pump for troubleshooting (turned out to be a blown capacitor). That's when I noticed the way they had it wired and disconnected the 120V portion of the circuit.

I wasn't sure if this was more shoddy work or if it was practiced (i.e. relatively safe) to use the well casing to ground and provide a return path to the power station for a remote pump house 40-ish years ago.

And my brother hasn't gotten power to the trailer he just moved in back there and wanted to temporarily use power from those buildings, so I just wanted to make sure I was justified in refusing to hook the power back up.

Thanks for the advice
Old 09-18-17, 06:16 PM
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Many older wells were connected with no ground wire down to the pump.

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