Convert 120v Light to 12v Low Voltage Using Existing Wiring?

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
Topic says it all. My idea is to get an Intermatic transformer and use the existing wiring to the lams and use the same lamp housings with perhaps a screw adapter for the bulb. Is doing something like this considered safe and legal?

The reason is that a tree root damaged the PVC conduit going to the spa light. After it rains, the GFCI will trip if the spa light is on for more than 5 minutes or so. The GCFI circuit has been replaced but the behavior is the same. There is likely a from water in the ground but barely (since it doesn't trip for after 5 min). My thinking is that reducing the voltage from 120 to 12 will not only drastically reduce the chances of a short (it would not overcome the resistance) but there would be piece of mind with low-voltage current going to the pool instead of 120v should a breaker fail.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,018
San Clemente, CA
What does the conduit have to do with the light? The light cord is watertight and the conduit is typically full of pool water anyway.

The GFI is tripping for a reason and the issue needs to be fixed correctly.

There have been a couple recent pool electrocutions that have resulted in death. I wouldn't take any chances.
 

atttech-2

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TFP Guide
Jul 24, 2015
1,185
Central Valley CA
If you know about where the conduit damage is I would plug it at the pool so the hole you dig to repair it does not fill with water and cut and repair the conduit. Pvc is easy to cut and repair especially if you heat it up a bit. Then you can pul in a new safe line.
 

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
What does the conduit have to do with the light?

The conduit houses the electrical wire that feeds electrical power to the light.

The light cord is watertight

The electrical wire from the light cord (which is only like 3 feet or something right?) all the way to the nearest junction box is not watertight.

and the conduit is typically full of pool water anyway.
It is? Because the copper wire in the junction box that leads to the spa light is definitely not meant to be submerged in water.

There have been a couple recent pool electrocutions that have resulted in death
Were they killed by 120v systems or 12v?

I wouldn't take any chances.

I'm not. That's why the spa light is disconnected at the junction box until i figure this out.
 

duraleigh

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Apr 1, 2007
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Welcome to the forum. :wave:

bdavis466 is absolutely correct. The pvc conduit from the light niche to the surface is flooded. If you have wire going into (and out of) that pvc conduit that is not completely waterproof, that is a big problem and dangerous.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,018
San Clemente, CA
The conduit is nothing more than a means to route the pool light to a listed pool junction box. The conduit needs to be water tight because it is completely flooded and equal to the water level in the pool. This is why the junction boxes must be 8" higher than the water level of the pool, regardless of how far away they are.

Damaged conduit is not a good thing because you are likely losing pool water through that cracked portion. What makes you certain the conduit is cracked? Even if the conduit is broken or cracked, the pool light cord would also have to be damaged to cause the GFI to trip. Why it takes 5 minutes to trip is anyone's guess but you need to use that as a cue to take action. Switching to 12V isn't going to fix the damaged wire (if that is the case) and you lose GFI protection completely on low voltage lines.

While 12V systems are generally considered safer, the situation you are describing is very unsafe.

I don't understand this 3' cord you are talking about. The pool light cord runs continuously from the light to the junction box and IS watertight.

The deaths were likely 120V systems but 12V can cause just as much trouble.

The copper wire you are refering to may be the bond wire which should be an insulated stranded #8 copper wire. There should be no bare copper wires in the pool light niche or conduit.
 

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
I don't understand this 3' cord you are talking about. The pool light cord runs continuously from the light to the junction box and IS watertight.

Yeah I just watched a video and learned that. I misunderstood how it worked, my mistake sorry.

Damaged conduit is not a good thing because you are likely losing pool water through that cracked portion. What makes you certain the conduit is cracked? Even if the conduit is broken or cracked, the pool light cord would also have to be damaged to cause the GFI to trip. Why it takes 5 minutes to trip is anyone's guess but you need to use that as a cue to take action. Switching to 12V isn't going to fix the damaged wire (if that is the case) and you lose GFI protection completely on low voltage lines
The entire patio in the area where the conduit would be run has been lifted up from a tree root. It looks like earthquake damage it's so bad. I don't know if the cable is damaged but I'm pretty certain the conduit is. I just opened up the lamp housing and even though there was a tight vacuum seal around the gasket, there was a lot of moisture in there and the contacts are very badly corroded and caked in aluminum oxide residue. The short could be coming from that.

I'm thinking I could clean the contacts and run the thing dry for a while to see if it trips?

Replacing the housing is not an option. It can't be pulled through, believe me I've tried everything including wrapping it around a steel bar. The conduit makes a 180 degree turn somewhere between the niche and the j-box. The lamp literally faces the j-box. I need to figure out a way to repair this. There is no other option barring some battery powered unit controlled wirelessly--does that even exist? Hopefully it's simply just a short caused by corrosion inside the housing. I found an article on how to fix that and seal it up with epoxy, haven't read it yet.

Assuming that can be done, back to the original question. Can the system be converted to 12V using the existing housing and cable? Couldn't I just use one of those j-box transformer adapters, and then pop in an Edison Screw to Bi-pin adapter in the housing and use a 12V LED bulb?


 

bdavis466

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Aug 4, 2014
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San Clemente, CA
No, pool lights are listed assemblies that are not designed to be tampered with. Even though your concrete has lifted, the conduit may not be broken. PVC is very flexible.

You should try a good quality silicone lubricant. I'd amazing the difference the line makes.
 

gwegan

TFP Expert
Apr 19, 2013
2,769
Sacramento, CA
I'm going to +1 Brian on everything above. I have my doubts that corded wires inside conduit are bad.

I'd also like to strongly suggest that you replace the Jbox with a new one.

Post some overall pictures of your pool, the inside of the niche, the jbox and the inside of the jbox as well as your pad and we can give you some ideas.

Is the light the only thing on the GFCI?
 

wjr75

LifeTime Supporter
Jun 6, 2013
895
IL
We had water getting into the junction box for our lights which was tripping the GFCI. We had one light replaced with a LED and they replaced the rubber plugs that go around the power cable in the lights nook which prevents water getting into the conduit. They also sealed the junction box cover with silicon caulk. We have not had any problems since this was done over a year ago.
 

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
No, pool lights are listed assemblies that are not designed to be tampered with.

What do you mean tampered with? The bulb is meant to be replaceable. I just realized that most 12v pool light bulbs use regular edison screws so I wouldn't even be modifying it in any way.

I tried silicon lubricant last time I tried to get it out which was last summer. I guess I could give it another shot.

Is the light the only thing on the GFCI?

No there's a pool light which works fine. It only trips when the spa light is connected.


- - - Updated - - -

Thanks gwegan and wjr75 the j-box very well could be the culprit.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,018
San Clemente, CA
Call the manufacturer of the light and ask them if that's an acceptable practice. They would be the ideal point of contact.

Then go to your building department and ask an inspector for his opinion.

Finally ask your family and every person who may potentially enter your pool how they feel about it.

You will not find anyone here that will tell you that a correct fix is not the best and only option. You seem to have your mind made up but if you are looking for support on not fixing the actual problem, you won't get it from me....
 

gwegan

TFP Expert
Apr 19, 2013
2,769
Sacramento, CA
Here's the deal with lights. They are designed a certain way for a reason. The NEC is written that way for a reason. The principal reason is to reduce the risk of electric shock. Work arounds are not something that is ok.

I would call a good industrial electrician. They have ways of getting things through conduit. Its worth the effort. But retrofiting a fixture is not something you can do.

I would be figuring a way to replace the light fixture (and cable) and the junction box. Put up some pictures of the pool area maybe we can help.
 

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
Okay I must not have been clear. I am not "retrofitting" any fixtures beyond changing a bulb. I asked if using a bi-pin adapter was possible before but the question is now moot since I discovered 12V pool bulbs use edison screws. I am perfectly comfortable putting a 12v 9 watt LED bulb into a housing designed for replaceable 120V 500 watt incandescents and using a 75 watt isolation transformer to feed it low voltage power. Not only am I comfortable with it, but I am highly uncomfortable leaving my fully functioning 120V pool light as-is. Given what happened to my spa light, had the GFI failed someone could have died. I want the inherent safety not just for my family but for whoever lives here 30 years from now. That is why I am replacing my pool light (not my defective spa light--yet) bulb with a 12V bulb and sending 12V to the J-box via a transformer. None of my plans violate the NEC. And I expect to see them make 120V pool lights illegal in the coming decades. They are a needless danger and a relic. Thanks to very recent developments in LED lighting there people have no business sending a dangerous level of electrical power to a swimming pool.

The lamp housings cannot be replaced without major excavation and destruction of the patio. This is a fact. I am not being lazy or cheap about it. It's simply not coming out. Last night I dumped 1/2 quart of wire lubricant into the conduit and it still won't budge in either direction. Because of this the spa lamp which is tripping the GFI will not be reconnected. I may hire an electrician to give it a try and I may redo the patio someday, but until then it is toast and I'm probably going to snip the housing off the cable and take it out for good. That is why I inquired about alternatives such as a battery powered remote control light.

Here are some photos. Note that the watertight sheath part of the light cable does not extend to the J-box. I don't know why but see so for yourself.


 

Attachments

dtlight

Well-known member
Jun 28, 2012
94
You are absolutely wrong about low voltages being capable of killing people that are in water. It's the current that kills, not the voltage. It only takes about 100 milliamps to be fatal (or 0.1 Amps,) and in the water where your skin resistance is greatly reduced the voltage necessary to get that much current through your body is also greatly reduced. The GFCI protection on 120V pool lights and outlets in your bathroom and kitchen are designed to remove power when 5 milliamps of current are flowing somewhere they should not.

https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html
 

bradj

Well-known member
Jan 19, 2016
157
TX
More than likely the reason you are tripping the GFI is due to damaged/worn out conductor insulation in your electrical circuit . Long and short, as temperature increases(current flowing through wire when lamp is on) resistance decreases. After a few minutes the old and worn out insulation becomes more susceptible to alow current to flow from the Ungrounded conductor(Hot wire) to anywhere with a path of minimal resistance to ground(conduit full of water etc..). It doesn't take much for a GFCI to trip, typically just a few milliamps.

I'd just repull an entire new lamp assembly and not worry about trying to retrofit to a new technology. If you are having an electrician come out, make sure he brings a megger and knows how to use it properly.

Regarding 12V and shock electrocution, you've made some assumptions that just aren't correct.
 

balderdashian

Member
Apr 2, 2016
10
Los Angeles, CA
You are absolutely wrong about low voltages being capable of killing people that are in water. It's the current that kills, not the voltage. It only takes about 100 milliamps to be fatal (or 0.1 Amps,) and in the water where your skin resistance is greatly reduced the voltage necessary to get that much current through your body is also greatly reduced. The GFCI protection on 120V pool lights and outlets in your bathroom and kitchen are designed to remove power when 5 milliamps of current are flowing somewhere they should not.

https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html
Your link uses 42 volts as the minimum. I edited out my definitive claim though I shouldn't have said that. But maybe I'll take some photos of me swimming with a car battery some time.

- - - Updated - - -

More than likely the reason you are tripping the GFI is due to damaged/worn out conductor insulation in your electrical circuit . Long and short, as temperature increases(current flowing through wire when lamp is on) resistance decreases. After a few minutes the old and worn out insulation becomes more susceptible to alow current to flow from the Ungrounded conductor(Hot wire) to anywhere with a path of minimal resistance to ground(conduit full of water etc..). It doesn't take much for a GFCI to trip, typically just a few milliamps.

I'd just repull an entire new lamp assembly and not worry about trying to retrofit to a new technology. If you are having an electrician come out, make sure he brings a megger and knows how to use it properly.

Regarding 12V and shock electrocution, you've made some assumptions that just aren't correct.
Thanks but the circuit works just fine with the pool light as well as a gazebo light on. It only trips when the spa light is connected at its nearby j-box. I'm unable to pull the cord.
 

danpik

TFP Guide
Jun 4, 2012
1,725
western NY
I have stayed out of this one untill now. Looking at the picture you posted kind of confirmed a suspicion I had about the problem you are having. Usually if a pool light is tripping a GFCI it is because the lamp housing has failed and water was getting inside. The other failure point can be in the wiring but it is rare as the cable assembly is rated for underwater use. If the cable gets damaged it can be the source of the problem. Your cable problem seems to be a splice somewhere in the conduit that has failed. Untill you dig it up and find the splice it is any guess as th where it is and how they did it. My best guess is there is a buried junction box that the wires are clamped to. This may be the reason why you can not pull the cable/wires out.


I kind of chuckled when I read this comment... But maybe I'll take some photos of me swimming with a car battery some time. I have a pretty vivid imagination.

Actually putting a 12 volt battery in the pool will do nothing as the potential difference will only be between the two posts of the battery.