12V Pool Light - LED Bulb Replacement, GFCI Protection, WiFi Switch


New member
Apr 17, 2015
Tampa, Florida
Sorry for the long post - but wanted to make sure that I explained all of the troubleshooting up until now.

Pool built in 2005 - original light fixture Pentair Hayward 7883XX, 7843XX R-40 12 volt 300 watt with a halogen bulb. The bulb burnt out so I replaced it with a 12 volt 35 watt LED light bulb from Florida Sunseeker Pool Tone® Color LED Pool & Spa Lights and Bulbs. I used a new gasket, submerged the light housing for a week before reinstalling, and there is definitely no water leakage. No issues with bulb, water leakage, etc.

After a few months, I decided to replace the old Intermatic Remote Control with a Meross WiFi HomeKit switch. While swapping out the switch, I noticed that the original wiring done by the electrician had the 120 volt feed to the Intermatic Remote direct from a regular non-GFCI breaker and was also not wired to the load side of the GFCI outlet that was feed from the same breaker. The switched output then goes to the 12 volt transformer input.

I thought it would not hurt to put the new WiFi switch to the load side of the GFCI outlet. As soon as I turned the breaker on, the GFCI outlet trips. I researched and could not find any issues with using a WiFi type switch with GFCI.

I then did the following to troubleshoot:
  1. Disconnected the switched output from the WiFi switch feeding the transformer - GFCI outlet trips (just the switch caused GFCI to trip)
  2. Tried a different GFCI outlet (new one) - GFCI outlet trips
  3. Purchased a new dedicated GFCI breaker to use for the light circuit only - GFCI breaker trips
Based on this, I assumed there was an issue with the WiFi switch and GFCI. While I figured out the next steps, I removed the WiFi switch and decided to direct wire the 12 volt transformer and would just turn off the breaker to turn the light off until I figured out my next step (was thinking I would need a different brand/model WiFi switch).

I then had the following results:
  1. Turn on the breaker with transformer input wired to the load side of GFCI outlet, and the GFCI outlet trips
  2. Wired the transformer to the GFCI breaker, and the GFCI breaker trips
  3. Disconnected the light fixture wiring from the transformer but kept the input side connected - tried with both the GFCI outlet and GFCI breaker (two separate circuits) neither one trips (issue is not with the transformer)
  4. Tested light fixture wiring with Fluke meter - no shorts between wires, to ground, etc. Line to neutral on fixture wiring measured out at 5 to 6 meg ohms (note that LED bulb was still in fixture)
Based on this, I am extremely puzzled. According to everything I have been able to find, it is not required but is OK to wire a 12 volt light to a GFCI. I did not find complaints about issues with 12 volt lights and GFCI. I could not any issues with LED light bulbs and GFCI. I called the LED bulb vendor, and they stated there should be no issue with the LED bulb and GFCI.

Some of what I have read is to not worry about putting the 12 volt light on GFCI - it is not necessary.

Can anyone provide insight on 12 volt lights, LED light bulbs, GFCI protection for these, etc.? Do I just not worry about the GFCI protection because it is 12 volt?


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The short answer to your GFCI trips is you have the neutral miswired someplace and running to the panel neutral and not the GFCI. I can't say where without seeing details of the wiring.

Wifi switches can be tricky because they vampire current and stay on even when the device is off and the GFCI thinks that vampire current is leakage and it trips.

12V pool light transformer do not need to be on a GFCI if the wiring will originate at an isolating transformer. The secondary conductors from this transformer must never enter raceways or other enclosures with other conductors, however, in accordance with Sec. 680-5(c). GFCI protection is not required for these systems.

As with most electrical stuff the devil is in the details.
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