120v with GFCI versus 12v with transformer?

[Henjan53]

I had an older Pentair wet niche Intellibrite pool light that died; it had a transformer built into the housing that stepped down the voltage from 120 to 12 v. I measured it feeding 12v to the light board, but the light board was fried, and when dummy here put it all back in the pooI while waiting for a new LED light borrd I managed to get water in it and fry the transformer, too. SO- I am faced with getting a whole new light setup. I can get a 120v color LED , but then I need to put in a local GFCI in the light circuit. OR- I could get a 12v light setup, but then I'd need to add a 12v stepdown transformer in the circuit.
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The 120 v power to the light comes from a surface mounted J box behind my pool cover bench (the cover rolls up into this) , and the 120v to the cover motor also is fed from this J box. I guess all of this was OK when it was installed, because the light housing had teh step-down transformer inside it. There is an elevated on/off switch box on a stand near the pool sand filter that controls only the pool light, and it feeds into the old Intellibrite dial-type light selector controller which in turn feeds the J box light hookup. A separate elevated switch next to the main light switch controls power to the filter pump and to the pool cover. BUT- the double breaker marked 'Pool' back inside the house shuts off everything- filter+ cover and pool light.

Am correct in assuming that :
1) If I get the 12 v light , I can put the transformer between the J box and the pool light (in a watertight box, of course)?
2) If I get the 120v light, I can put a GFCI unit between the J box and the pool light (in a watertight box, of course)?

It just seems to me that since the cover motor is fed through the same J box in whichall wiring is currently carrying 120v , it would be simpler/better (and safe) to go with 120v light add a local GFCI as stated in 2) above?

Help!

 

[Rocket J Squirrel]

I don't believe a truly waterproof box exists. If has wires coming in and going out, water can get in. I spent years trying to waterproof a junction using boxes and failed.

Why not replace the circuit breaker with a GFCI breaker?

 

[nuttyp]

Welcome to TFP! I applaud your post and desire to do the right thing, the safe thing. Still, I'm troubled by some of the information you provided. I think the wisest thing you could do would be to avail yourself of a licensed electrician to consult on how to bring the entire electrical system up to NEC 680 code. Generally that means finding someone who is not just licensed but also experienced with pool systems and well versed in NEC Article 680. While it's not rocket science, it's also nontrivial when you consider using only items listed for pool use, their allowed locations/distances, when GFCI is required, branch circuit standards, equipment bonding, etc. You can read much more here Electrical Bonding - Further Reading and within that area is also a link to the freely available NEC 680 detail.

Among the specific things from your post: As you probably noticed, your 120V light should have been on a GFCI breaker all along. Not sure how many years we'd have to go back for the NEC code to allow that without GFCI. My read on NEC 680 is that the cover equipment too must be GFCI, as it too is in proximity and 120V. Also if I understand correctly, you "fried the luminaire's internal transformer/electronics" when power was applied with water present. If I'm reading that correctly, it would seem that, at least for a moment, 120V was applied to the pool water. If so, big danger - run web search for "man dies working on pool light". Perhaps you or others were saved by excess current through the water to the nearest ground or bonding wire and it tripped the breaker. Or you turned it back off, also saving someone.

Next thought - which is sometimes controversial - is I would go with GFCI on the light circuit regardless of whether you decide on 120V or 12V. As far as I know, NEC 680 does not require GFCI on the primary of a transformer listed for pool use for a 12VAC luminaire, but many of us still use GFCI on the primary for those 12V fixtures, in part because there are still cases of multiple faults where it killed someone. Time-degraded wiring in a transformer enclosure, missing or corroded ECG (Equipment Grounding Conductor), unbonded metal transformer box, transformer used that is not listed for pool use, etc., combine to create the danger and the GFCI is such an easy and inexpensive way to make it safer. I think one went like this: ECG (green wire typically) corroded off the transformer enclosure, wire nut fell off the line to primary, it touched the metal enclosure and electrified the pool. Detail was not provided for why high current through bonding wire didn't trip the breaker, but a properly working (and tested) GFCI would have saved the man.

Of course the simplest way to "GFCI" everything is to replace the panel breaker you described as a "double breaker", presumably 2-pole / 220V, with GFCI. Given the number of loads on that (pump, cover motor, light, other?) and downstream J-boxes I also wonder if that breaker and all downstream wiring is sized and wired appropriately. Most pumps call for a dedicated circuit, I think, so not sure if you're even within code to tap off one leg (plus neutral) for the light and cover, as it seems was done. Nor am I certain a 2-pole GFCI breaker will function properly if one leg is used that way for the light and/or cover portion of the circuit.

My last comment is more of a question and perhaps belongs in another new thread, but I'll mention it here in case anyone wants to comment.... Given the widespread occurrence of water intrusion into luminaires in wet niches, why in the world are there still so many 120V lights still being sold and used? To save us we rely on the bonding and the ECG? Even though it seems inevitable that 120V will one day touch the water? Frankly I don't want 120 volts anywhere near my pool, even if I've run every test documented by Mike Holt in this video and accompanying documents. Every day there are new posts about water getting into the luminaire, and just about every one I've taken apart had some water inside. It never happened to mine (12V btw), but I am meticulous to clean the glass and contact surfaces, adding non-petroleum lube like jack's magic lube, then tighten well, etc., using of course a new gasket as specified and installing it with the stamped gasket "pool side" facing out. Okay, it is admittedly tempting to use the old gasket if it cleans up well Best wishes!