Pool light tripping GFI breaker when turned on

Cathy16

Member
Aug 2, 2021
7
Orlando, FL
Hello All! I have an inground pool built in 1973. It does not have an attached hot tub. There used to be a junction box connecting power from the pool light to the breaker box. The connection was severed when we bought the house 6 years ago. (Yes, power was off at the breaker.) We decided to try and get the light working. The bulb was bad and the housing had seen better days. We replaced the light fixture and ran the power cord back to the breaker box (approximately 70 feet). Power is 120V. The ground wire from the pool niche/recess was connected to a ground rod (6 feet deep). A new GFI breaker (20A) was installed. There is a light switch inside the house that turns on the light. Testing the GFI breaker with the light switch off trips the breaker. With the breaker on, turning on the pool light at the light switch immediately trips the breaker. Any ideas as to why? We also changed to bulb in the new housing to an LED bulb. No leaks into the new housing from the bulb change.

Thanks.
 

Poolbreh

In The Industry
Jul 31, 2021
272
San Diego
Was it working before the bulb change? Is it an led that screw in like an incandescent? You can either disconnect load side of gfci and see if it trips, if it does(bad gfci) if it doesn’t it’s after. They also have little gfci testers fairly cheap that give you somewhat of an idea. You can also open light up remove led, make sure it’s dry and test it without led, if it doesn’t pop and there is no water the led is causing the short. You can even try to remove test, screw in test to confirm.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,080
Northern NJ
Pool Size
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Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The ground wire from the pool niche/recess was connected to a ground rod (6 feet deep).

The ground wire from the light should go back to the ground bar in the CB panel.

A new GFI breaker (20A) was installed. There is a light switch inside the house that turns on the light. Testing the GFI breaker with the light switch off trips the breaker. With the breaker on, turning on the pool light at the light switch immediately trips the breaker. Any ideas as to why?

Both the hot wire and the neutral from the light need to go to the GFCI CB. The GFCI CB has a neutral pigtail that connects to the neutral bar in the CB panel.

You are getting tripped up in changing a non-GFCI 120V circuit to a GFCI circuit. The neutrals need to be wired differently.

The neutrals in the circuit need to be moved from connecting to the neutral bar in the CB panel to the specific GFCI CB the hot wire is connected to.

Having the light switch further complicates your wiring.

Post pics of all of your wiring and maybe I can help you sort it out. Or this is an easy job for an electrician to rewire.

 
Last edited:

Poolbreh

In The Industry
Jul 31, 2021
272
San Diego
Sometimes new things can be faulty, if it worked before led light was put in and stopped after. I would say led was the culprit. Yes the incandescent led have drivers or mini transformers that convert 120-12v. But it’s always a process of elimination.
 

Cathy16

Member
Aug 2, 2021
7
Orlando, FL
The ground wire from the light should go back to the ground bar in the CB panel.



Both the hot wire and the neutral from the light need to go to the GFCI CB. The GFCI CB has a neutral pigtail that connects to the neutral bar in the CB panel.

You are getting tripped up in changing a non-GFCI 120V circuit to a GFCI circuit. The neutrals need to be wired differently.

The neutrals in the circuit need to be moved from connecting to the neutral bar in the CB panel to the specific GFCI CB the hot wire is connected to.

Having the light switch further complicates your wiring.

Post pics of all of your wiring and maybe I can help you sort it out. Or this is an easy job for an electrician to rewire.

It's raining now, so give me some time to get a picture of breaker box.
 

Cathy16

Member
Aug 2, 2021
7
Orlando, FL
Sometimes new things can be faulty, if it worked before led light was put in and stopped after. I would say led was the culprit. Yes the incandescent led have drivers or mini transformers that convert 120-12v. But it’s always a process of elimination.
It was not working before we installed new light. The bulb on the old light housing was bad (it rattled when I shook it) and it was corroded at base for the bulb threads. Wires from the old light housing to the breaker box were completely severed until we replaced the light. I'm sure once upon a time the pool light worked, but not while I have lived here.
 

Rocket J Squirrel

Silver Supporter
Bronze Supporter
Jun 7, 2018
1,227
Alamo, CA
Pool Size
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The ground wire from the pool niche/recess was connected to a ground rod (6 feet deep).

The ground wire from the light should go back to the ground bar in the CB panel.
^ This. With the ground going to distant earth, the GFCI sees that as a current leak (assuming the GFCI breaker is properly wired).
 

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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,080
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
^ This. With the ground going to distant earth, the GFCI sees that as a current leak (assuming the GFCI breaker is properly wired).

GFCI breakers do not monitor current on the ground. They look for balanced current between the hots and neutral wires. Which is why both hot and neutral wire have to connect to the GFCI device.

Current can leak into the ground which will trigger the GFCI as an imbalance between hot and neutral.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,080
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
What you call "pool power" is the light?

The white (neutral) from the light should not be connected to the ground bus or neutral bus.

Show me the wiring for the wall light switch that has the black and white wires running into the CB box.

See https://images.thdstatic.com/catalog/pdfImages/37/371687c0-0067-403e-a194-c0a0015f2c18.pdf

The white wire from the switch connects into D and is a hot wire and should be wrapped with black electrical tape at both ends to indicate so.

The white wire from the light connects to E.

1628284466241.png

I don't think you should be using a 20 amp breaker. Is the wiring to the light 12 gauge? Is the wire in your CB panel 12 gauge? If 14 gauge then you should be using 15 amp breakers.
 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
28,255
We replaced the light fixture and ran the power cord back to the breaker box (approximately 70 feet).
Can you explain exactly what was done here?

The gfci breaker is also an arc fault breaker which might be a problem with the LED light.

In any case, the entire system is not safe and you really need to have a qualified electrician review everything and bring it up to code.

I would not allow anyone to swim until the electrician gives the ok.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,080
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
You have an old subpanel that connects the grounds and neutrals together on one bus bar. The National Electrical Code (NEC) requirement for separated neutrals and grounding wires in a subpanel and separate neutral and grounding conductors back to the main panel, when both panels are in the same building, dates to the 1999 revision. The requirement for separation of neutral and grounding conductors in and to a subpanel in a separate structure first appeared in the 2008 NEC.

At the main service panel, the neutral and grounding wires connect together and to a grounding electrode, such as a metal ground rod, which is there to handle unusual pulses of energy, such as a lightning strike. This is the only point at which the neutral connects to ground.

If the neutral and grounding wires are connected together anywhere else, the return current that is meant to flow on the neutral will flow back to the panel on both the neutral and ground. This is dangerous for several reasons; most importantly, if there’s a poor connection or break in the grounding wire and the neutral wire, the parts of the grounding system on the far side of the break (from the panel) will be energized and present a shock hazard. This is a big deal, because any exposed metal part of a fixture, tool, or appliance may shock or electrocute you—and breaks or poor connections happen more often than you’d think.

In addition your pump CB is not GFCI.

All these issues are why the safest thing is to have an electrician upgrade that panel to meet current NEC.
 

Cathy16

Member
Aug 2, 2021
7
Orlando, FL
What you call "pool power" is the light?

The white (neutral) from the light should not be connected to the ground bus or neutral bus.

Show me the wiring for the wall light switch that has the black and white wires running into the CB box.

See https://images.thdstatic.com/catalog/pdfImages/37/371687c0-0067-403e-a194-c0a0015f2c18.pdf

The white wire from the switch connects into D and is a hot wire and should be wrapped with black electrical tape at both ends to indicate so.

The white wire from the light connects to E.

View attachment 362152

I don't think you should be using a 20 amp breaker. Is the wiring to the light 12 gauge? Is the wire in your CB panel 12 gauge? If 14 gauge then you should be using 15 amp breakers.
Wired as directed. Pool light works. Does not trip breaker when turned on and off. I will take care of the rest of the suggestions (GFI on pool pump, etc.) soon. Thank you all for the help and guidance.
 
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