Add GFCI protection to old pool equipment?

Mr. Serious

Member
Location
Oklahoma, USA
Occupation
Electrical Contractor
I worked on a friend's house, upgrading the main service from 100A to 400A, changing out the old Federal Pacific panel in the house, and making a few changes to the pool electrical supply, trying to make sure it was good from a safety standpoint.

The pool pump and spa pump/heater were fed from an old type CH panel, still in good condition. Originally it had some of the low-voltage wires running through the same main conduit as the feeder, it had no separate EGC to the pool panel, and it had no GFCI breakers.

So, I removed the low-voltage wiring, changed the 2-pole 20-amp pool pump breaker and the 2-pole 60-amp spa pump breakers to GFCI breakers. I did this pretty early in the process, before re-doing the feeder to the panel and separating the neutral and ground within this subpanel.

As I was out there doing the final work, the homeowner said occasionally those GFCI breakers would both trip, and I thought it might have to do with current flowing on the ground wires when heavy loads such as the house air conditioner started, before the main service had been upgraded and while the pool panel neutral and ground were still bonded. I thought the problem would go away once everything was done.

Now, everything has been done for about a month. Voltage no longer sags when the main house A/C turns on, but I just found out a few days ago the spa breaker (60A GFCI breaker) has not been staying on at all. The homeowner thought it was a bad pump motor and replaced it, only to have the problem continue.

All this equipment is very old, probably 20 or 30 years. I think I once read that one shouldn't try to put such old equipment onto a GFCI breaker because it wasn't built for it in the first place, and was built with small internal ground faults that will trip a modern GFCI breaker. Is that correct? I wish I could get out there to test it, but the place is two hours away and I've gotten busy with other things.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
There really is no such thing as current on the green wire causing the GFCI to trip. The GFCI trips when there is an imbalance in current between the line and neutral that it is monitoring. That's it. Somewhere downstream of the GFCI there is a ground fault of some sort. Since the guy replaced one of the parts in his spa it probably isn't that part. Could be wires that have failed intermittently over the years. My inclination would be to go in and rip out the wiring and start over since it's not probably going to amount to a whole lot of work and see if the problem goes away. And if not you may have to start changing things until you change enough stuff that the problem goes away. These kind of intermittent problems are things I hate because they Don't respond well to normal troubleshooting techniques.
 

Mr. Serious

Member
Location
Oklahoma, USA
Occupation
Electrical Contractor
I arranged to go out there on Saturday, so I'll let you know how it goes this weekend. From my understanding, the problem used to be intermittent, but now it is tripping all the time, so that should make it easier to troubleshoot.
 

retirede

Senior Member
Location
Illinois
I arranged to go out there on Saturday, so I'll let you know how it goes this weekend. From my understanding, the problem used to be intermittent, but now it is tripping all the time, so that should make it easier to troubleshoot.

As mentioned above, start with the spa heater.
 
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