it looks like many who were helping you along have bailed on this. and for good reason. i know you are trying to save money, but just hire a pro......
Now, just to be sure...is the wiring from the house supposed to go to the LOAD or LINE and the wiring to the tub to be on the LOAD or LINE? Or both on LINE? etc... Might seem like a dumb question, but I'd like to be sure.
So, I hooked up the bare copper from the house to the grounding bar and the GFI is tripping. Before it trips ( split second ) the outlet testor shows an OPEN GROUND.
Should I disconnect my heater and test again? If it's the heater, would the tub start up fine, just no heat?
It looks like he has a bad heating element. I'm guessing the heating element is similar to the ones on an electric stove, you don't get a shock if the element is touched or you stir something in a pot because of insulation. If part of the insulating material is cracked then electricity can flow directly into the water. That should have tripped the GFI but something was wired wrong. It sounds like he might have that corrected & now needs to replace the heating element with a new one. He should have a pro inspect his work, if the insulation had failed while he was using the spa we'd be sending flowers.
I noticed the pressure switch was beeping when I held the voltage testor to it. As soon as I turn the tub on the GFI is tripping and when I disconnect the third black wire the tub runs and doesn't trip the GFI ...is this part of the heating system?
There's no voltage in the tub water or water through the pipes when this third black wire is disconnected...all other wires for the heater are connected and no GFI tripping...
So, GFI doesn't rip unless the third wire down is connected. Seems strange to have 3 hot wires going to this..Could this be my OPEN GROUND problem?
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Wiring from the house would go to the LINE side. The connection to the hot tub would be on the LOAD side.
Yes disconnect the heater and test again. The GFCI is now working as it should because there is a low impedance (low resistance) path to ground through the water bond. Before the only path it had was via you you touching the water and the ground which had a high enough resistance to stay above the 6mA limit of the GFCI but low enough for you to feel a shock.