Swimming Pool Bonding

[inspector 102]

I have an installation where the bonding wire that connects to all the metal fixtures has been run back to the pump motor. The circuit to the pump motor is protected by a GFCI breaker that trips as soon as the bonding wire is connected to the bonding terminal on the pump. As an inspector, I have always seen the bonding jumper connected at this point without any problems. What might I need to look for as a potential problem. The homeowner says they will simply leave the bond off and I have told them they can't do that. Any thoughts on potential problems would be greatly appreciated so I can advise the owner a starting point.

 

[jwelectric]

Re: Swimming Pool Bonding

Some where some how the bonding grid is carrying current that is causing an imbalance that the GFCI is seeing would be the only cause that I can think of. Check all the joints and terminals.

 

[hurk27]

Re: Swimming Pool Bonding

Some where some how the bonding grid is carrying current that is causing an imbalance that the GFCI is seeing would be the only cause that I can think of.

If the bonding grid had current on it this current would not trip the GFCI for the pump. It does sound like the motor windings might have leakage but then it should trip with the EGC of the circuit feeding the pump?

There may be sevral reasons that this is happing but the one that seems to click in my head is if the grounding conductor has been improperly connected to the load neutral on the GFCI breaker. This would cause the EGC to act like a neutral and provide full circuit current between it and the hot, but when it is connected to the grid it causes a leakage to earth which will trip the GFCI.
The only other thing I can think that would produce this would be the EGC for the pump has been isolated and the pump has a bad winding and has leakage current to case so when the grid is connected to the case bonding terminal it trips the breaker.

 

[jwelectric]

Re: Swimming Pool Bonding

Yep, we are saying the same thing Wayne.

Some where some how the bonding grid is carrying current that is causing an imbalance that the GFCI is seeing would be the only cause that I can think of.


[ July 08, 2005, 06:58 PM: Message edited by: jwelectric ]

 

[hurk27]

Re: Swimming Pool Bonding

Yep, we are saying the same thing Wayne.

I didn't think so?

What I was trying to convey was is the grid has current on it or voltage from a source other then the GFCI breaker feeding the pump then if the grid is tied to the EGC of the pump motor all that will happen is current in the EGC which is only connected to the grounding bar in the panel. How will this trip the GFCI breaker for the pump circuit? Current can flow all day long on a grounding conductor of any GFCI protected circuit as long as the current is being supplyed by another source other than the GFCI breaker supplying this pump circuit This is how a GFCI works. A GFCI monitors the current between the hot and neutral on 120v three wire circuits and both hots on a 3 wire 240 volt circuit and to go one more on a 4 wire 120/240 volt circuit both hots and the neutral is monitored. The grounding conductor (EGC) in all of these circuits are not monitored because of one main reason. The return path that a person be contacting is not always going to be the EGC ran with the circuit conductors. It can be Earth, or other metallic paths. This is why GFCI's still function on circuits without a EGC ran with it. so you can apply all the neutral current from any circuit other then the one being protected by the pump GFCI and it will not trip the pump GFCI.
But if the EGC for the pump is improperly connected to the load neutral terminal on the GFCI breaker then two things happen 1 the 5ma protection has just been raised to the current level of the circuit since it is now acting like a load neutral. And 2 if this grounding conductor comes into contact with any other grounding (grid) it will trip the GFCI just like any load side neutral would if grounded in a device box.

I have seen this happen but only on a 240 volt pump and a 2-pole GFCI that had a load side neutral terminal. The installer thought that there had to be a wire on the load side neutral for the GFCI to work and he just connected the grounding conductor to it. So when anyone touched the metal on the pump it would trip the breaker if they were also touching something grounded.

This is why I said the first thing I would check is the pump circuit grounding back at the panel.

 

[benaround]

Re: Swimming Pool Bonding

Inspector102,

This is just a thought. The pump circuit and say the required outlet have their neutrals criss crossed or their hots criss crossed.
So,GFIC neutral to pump ,GFCI hot to required outlet ,EGC to to both devices.

Non-GFCI circuit breaker,hot to pump ,neutral from neutral bar to required outlet.

Neutral and EGC at pump are touching somewhere but the hot comes from a regular breaker so GFCI won't trip. Now when you connect the bond wire to motor lug you transfer the fault thru the EGC to the outlet and that trips the GFCI breaker. Or not!

frank