Pool Equipment Electrical Problem

[footdale]

Cliffs:
- Pool pump is on a 220V circuit - always runs fine.
- Separate 110V circuit on GFI breaker (brand new) for pool heater/outdoor receptacle constantly trips when pump ground and heater ground are connected.
- Everything is fine if heater circuit is completely isolated from pump. This is hard right now since everything is mounted to a metal plate. I have to pull the receptacle off the metal box.
- I just want to make sure I get it hooked up right so no one gets shocked


Longer Version:
Pictures are below.

The old electrical was a mess, so I got all new boxes, conduit, and panel for my pool pump and heater control. I thought I understood electrical, but this issue has been driving me nuts. If all the grounds are connected together, the GFI breaker trips, even under no load. If I isolate the ground of the 110V heater circuit from the panel, then the breaker does not trip and the heater works fine. The problem is not with the heater, I got the same response when I completely disconnected the heater. I've checked continuity and none of the hot lines are shorted to ground.

The pump has a bare copper wire that goes underground and connects to the pool handrails. If there is a difference in ground potential between this ground and the ground where the breaker box is physically located, could that trip the GFI? I don't get though if everything is referenced to the same ground, why the GFI breaker trips.

In short, how should this be properly hooked up?

Thanks!
- Joe

Control Panel:

Breaker box:

Breaker box diagram:

Panel diagram:

Pump:

 

[westvirginia24976]

Someone else will surely respond, but I don't believe you should have tied your ground to your neutral screw on the receptacle as shown in your last diagram. I don't think that is your problem though if it only happens when both the pump and receptacle are energized. With that ground tied to the neutral screw like that it creates a current carrying situation as a return path to the breaker panel.

 

[footdale]

Someone else will surely respond, but I don't believe you should have tied your ground to your neutral screw on the receptacle as shown in your last diagram. I don't think that is your problem though if it only happens when both the pump and receptacle are energized. With that ground tied to the neutral screw like that it creates a current carrying situation as a return path to the breaker panel.

Yeah, I was just talking to someone about this. I assumed that since the neutral bus was connected to a ground rod at the main breaker box that the neutral wire was the same as ground. I assumed this because the previous installer did not run a ground wire from the box, and I didn't take good enough notes when I disconnected everything the first time.

 

[Andy in Pa.]

Remove that ground wire from the neutral screw. That is why your GFI is tripping. Neutral and ground cannot be tied together in a GFI circuit or on a GFI outlet.

 

[footdale]

Yep, did that and it's all working fine now. The absence of a ground wire to the location and seeing the neutral bus connected to a ground rod led me to wrongly assuming that neutral = ground. Obviously I have some more learning to do on AC electrical systems. Thanks all for the help!

-Joe