# low voltage question



## wraiths (Jan 13, 2006)

Got to install some 12v ac lights in a house and need help. Ok first question does low voltage lights need to be mounted to a box or can the connections be exposed? These lights have two insulated spade type connectors that plug into the light and from there go to the transformer. Also already installed two of these lights in existing ceiling boxes an hooked them up. The circuit that powers the xformer is gfci protected an when I turned them on the gfci tripped. Did the usual t/s an it only trips when the xformer is connected can you not run a xformer off of a gfci? Everything else looked good only thing I can think of is the xformer. Any help is greatly appreciated. No one can give me a straight answer about the lv connections needing a box or not. FYI the line voltage connections are in boxes. Thanks


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## ABLE1 (Apr 30, 2005)

wraiths said:


> Got to install some 12v ac lights in a house and need help. Ok first question does low voltage lights need to be mounted to a box or can the connections be exposed? These lights have two insulated spade type connectors that plug into the light and from there go to the transformer. Also already installed two of these lights in existing ceiling boxes an hooked them up. The circuit that powers the xformer is gfci protected an when I turned them on the gfci tripped. Did the usual t/s an it only trips when the xformer is connected can you not run a xformer off of a gfci? Everything else looked good only thing I can think of is the xformer. Any help is greatly appreciated. No one can give me a straight answer about the lv connections needing a box or not. FYI the line voltage connections are in boxes. Thanks



I will take a shot at this. Or maybe a couple extra.

Trying to Troubleshoot from a far?? This will be a little difficult. Some things to think about or consider.

1) Maybe the GFCI is really trying to tell you that there is an internal problem with the txfmr.

2) Maybe the GFCI is weak and should be replaced.


Things to try.

1) Plug the txfmr into another GFCI.

2) Try another txfmr.

3) Plug txfmr in to a non-GFCI circuit and check amps and test for shorts, voltages, etc.

You may have tried the above but it needs to be mentioned.

As for the holders/conectors being exposed I will beg off and let others chime in on that thought.

Good luck.

Les


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## mdshunk (Mar 13, 2005)

wraiths said:


> Got to install some 12v ac lights in a house and need help. Ok first question does low voltage lights need to be mounted to a box or can the connections be exposed?


Depends, in large part, on how the transformer is rated. Does it say "class 1" or "class 2" or something like that on it?


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## sparky66 (Nov 14, 2006)

In theory, a transformer wouldnt work with a GFCI. A transformer needs time to "saturate", thus an imbalance between line and neutral.


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## Sparky Joe (Apr 29, 2006)

sparky66 said:


> In theory, a transformer wouldnt work with a GFCI. A transformer needs time to "saturate", thus an imbalance between line and neutral.


Could you explain more on this subject

We do buildings with GFI mains and several xfmr's inside all the time.


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> We do buildings with GFI mains and several xfmr's inside all the time.


No... you do buildings with any main breakers over 1000 amps (and maybe smaller, if the engineer wants) with GFPE mains, not GFCI mains. Big difference. (I think you need GFPE on feeder breakers over 1000 amps now too. That sort of work is generally engineered, and I don't do too much big work anyway to remember that stuff.)

I have experienced low voltage transformers nuisance tripping GFCI's. This is sometimes the case when the homeowner gets some cord and plug connected undercabinet lighting for the kitchen. It was never clear to me before why these sometimes trip GFCI's, but coil saturation lag time sounds reasonable.

I see one potential red flag... exactly what GFCI protected circuit is powering these lights? If it's one of the kitchen countertop circuits, that's a no-no to supply hard wired lighting. If it's a bath GFCI, it _might _be okay, and it might not, depending on a few things.


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## RobertWilber (Mar 5, 2006)

article 411 allows BARE conductors under certain circumstances, and 411.4[a] specifically calls for installations to meet Chapter 3 if conductors are run through walls [which would mandate an enclosed junction], I don't see why your connections would need to be inside an enclosure
Can the source not be moved to a non-GFI outlet since the GFI does not protect the secondary of the LV anyway ... ?


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## wraiths (Jan 13, 2006)

Hey all thanks for responding let me see here I changed the xformer an the same thing happened. The xformer doesnt say if it is class 1 or class 2. One is 50watt an the other is a 150 watt. The outlet feeding the circuit is from the dining rm not the kitchen small app cir. It doesnt need to be gfci and I didnt install it just the way it was before . Not much on the circuit just a recept an a fan light in the rm. We added the lv lights in the rm an just picked up power in the switch box. Any more input on the exposed/concealed connections? As always thanks...


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## Sparky Joe (Apr 29, 2006)

wraiths said:


> Any more input on the exposed/concealed connections? As always thanks...


12v can be exposed, just do a nice job with it.

In fact I think that's why no one wanted to answer because they/we think it might ensue a hack job.


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> 12v can be exposed, just do a nice job with it.


Not so fast, Joe... Review 411.4 very carefully. 

It needs to have a "class 2" power supply or better to have exposed connections.


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## Sparky Joe (Apr 29, 2006)

mdshunk said:


> Not so fast, Joe... Review 411.4 very carefully.
> 
> It needs to have a "class 2" power supply or better to have exposed connections.


Good point MD, I didn't know these restrictions on low voltage lighting, or low voltage anything for that matter.

Though it strikes the question of whats the difference between a class 2 and a different transformer?


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## mdshunk (Mar 13, 2005)

Sparky Joe said:


> Though it strikes the question of whats the difference between a class 2 and a different transformer?


I have no idea. All I know is that if it does't say 'class 2', then you need to wire it with chapter 3 methods (in the case of a typical dwelling, romex and boxes and the whole nine yards). Boy, did I learn that the hard way. Cost me, big time. 

EDIT... sorry. Just read that I called you "boy". Just an expression.


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## Sparky Joe (Apr 29, 2006)

mdshunk said:


> EDIT... sorry. Just read that I called you "boy". Just an expression.


Does this insinuate that I'm a woman :furious: 

Which I will assure you all that the last time my girlfriend checked on top of a sink of a strangers bathroom on new years, I surely was not :thumbup:


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