Proper grounding of 3-wire submersible pump in metal well casing

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MichaelSK

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I placed a new 3-wire pump into metal well case. (The pump controller is inside the mechanical room in the house.) The broken cast iron well seal was replaced with a PVC well seal. There is no conductive (bonding) between all the well components (galv drop pipe, iron well casing, metal junction box, pump ground wire, ground wire from pump controller, house ground).

Previously the metallic junction box was mounted directly on the cast iron well seal and the entire system was bonded to ground. Now the ground wire only goes to the pump.

Should I bond the metallic junction box, iron casing, and galvanized drop pipe to the ground wire?
 

WorthFlorida

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This three wire pump, is it 120v or 220v? Is this a submersible pump? The ground you're referencing, is it a green or bare copper? Attach pictures if you can.
 

MichaelSK

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It's a 3-wire pump with a ground wire (total 4 wires with separate start and run capacitors in the control box). The green "ground" wire is bonded to the house ground back at the control box, which is in the house mechanical room.
 

WorthFlorida

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Anything that is metal box or metal conduit with electrical wires and connectors should be grounded for safety. That is should a wire nut come off or a live bare wire touch the metal box or conduit, the ground will cause a short to trip the breaker. If not the metal box or conduit could be hot and someone touching the box and is grounded, (i.e. bare feet), will get hurt. The cast iron well casing is really a ground. Any metal driven into the ground will be a ground.

It seems to read that you have an above ground pump with a cast iron housing and it is 220v. With an ohm meter, from the iron casing of the pump to the ground wire you should read zero ohms. If the casing is iron and you have galvanized pipe from the pump to the well, the pipe will be grounded through the pump housing. If your pump is of a glass composition, (plastic like), then there is no way for the well pipe to be accidentally electrified, therefore no "bonding" is needed. However, from the pump back to the house and any metal needs to be connected to the one ground. I hope this answered you question.

There is a topic called "ground loops". Wikipedia has info on it. With your old well connection you had two ground points. One at the breaker panel (probably s ground rod connection) and one at the well. In rare instances there could be a potential difference between the two grounds and current can flow between them. I worked in telephony most of my working life (39 years) and when a shielded telephone cable was run between two buildings, only one end was to be grounded.
 
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