12V transformer tripping GFI

[zwiller]

I figured since there will be alot of aether II's in commission this year some might benefit from this. 

I have a 12V lawn transformer feeding deck lights.  The tranny is wired to a GFI (not plugged in).  Works fine, but when it rains or sometimes for no reason at all the GFI trips.  Kinda reminds me of incans and art easel mini trees     It obvious is a pain having to reset the thing almost daily.  Really would like to fix. 

I originally did not wire the transformer to the GFI protection but thought "it was the right thing to do".  It's been a while since I wired it but I wonder if I wired it right (used GFI instructions).  Shared neutral maybe? 

Does anyone have any experience fixing something like this?  THANKS

[caretaker]

Two reasons the GFI is tripping, one it is picking up a ground fault (ratio of current coming back on the neutral) which exceeds the threshold of the device. Two the device is defective or to sensitive.  Most cases it is reason one and how you can prevent the ground fault is one make sure all the 120 volt connections to the transformer are sealed from moisture and use a in use cover with the GFI if it is plugged in outdoors. If it still trips when wet or damp try covering the transformer or moving so it doesn't get rained on.  If it still trips replace the GFI.
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[zwiller]

Thanks Jeff.  Pretty sure everything is watertight.  No in-use cover since nothing is plugged into the recpt.     Tranny is mounted underneath the deck in a wet free area. 

However, I just remembered I have a photo sensor to kick on lights.  Could that be a factor?   

This is all kinda bizarre since I just left the tranny for the aethers outside unprotected all winter with rain and snow and no problems...   

For some reason I bet if I didn't wire the tranny and just plugged in the the thing with an in use cover I would be fine.  But that wasn't cool enough for me 

[gatorengineer]

I had a similar issue when I was running my lights.  I dried out some connections and sealed them and the GFI stopped tripping.

To expand on caretaker, the exact current difference is 5 milliamps between the hot and neutral.  That is very small.  So it doesn't take much leakage current to get into some water and trip your breaker/receptacle.

Have you tried plugging the circuit into a non-GFI receptacle and see what happens.  If it runs, then you have something faulting to ground and since you said it happens when it rains, that is classic ground fault.  Somethings getting wet or something is getting moisture in it which is causing the problem.

If you think it is the transformer, then put it on some rubber or something to keep it from grounding itself that way you can track down the problem.  If the problem is inside the transformer and the case is grounded, that might be where the problem is.  You will just have to narrow it down.

[dudehenry3]

Do you have any other outlets on the circute that may be getting wet as well. Dose the transformer have a timer on it if so the motor may may be bad. 

[tbone321]

The easy answer is not to use GFCI there especially since it isn't doing anything for you in this situation. 

[zwiller]

Thanks for the replies. 

So, I decide to go tbone's way and forego the gfi protection.  I shut the breaker off and open the cover and I see the attached.

Obviously, the previous cover was a problem.  Hopefully THE problem.  So I installed an in use cover for added protection.

Also, I had problems with my deck lights not coming on when they weren't blown, go I got a small packet of dielectric grease at auto parts store and gave the bulbs a dab on contacts before installing for good measure. 

(fingers crossed)

[tbone321]

The thing is that there is no GFI protection on the secondary side of a transformer.  All the GFCI will see is the primary side and has no idea what is happening on the other (output) side.  The replacement cover may help if water is leaking in and giving some of the current that the GFCI is monitoring a different path to ground.  Putting grease in the sockets may help to prevent the contacts from corroding or prevent minor shorting issues but will not have any effect on the GFCI issue since they are on the secondary side of the transformer. 

[n1ist]

If you look at the bottom of the GFCI in the picture, it's obvious that water did get in.  So in this case, replacing the GFCI and the cover should fix the problem.   You are right that the GFCI won't protect the secondary of the transformer, but that should be current-limited anyway.
/mike

[zwiller]

I only wired the transformer to the GFI because I knew it could be done and I hadn't done it before.  I could really care less for the GFI protection...  Thought it was cool that I could do that.  Maybe even some day I could use that knowledge for something... 
   
But,

while we're at it... 

The direct wiring of the transformer is up to code even if not fed by GFI right? 

[caretaker]

I only wired the transformer to the GFI because I knew it could be done and I hadn't done it before.  I could really care less for the GFI protection...  Thought it was cool that I could do that.  Maybe even some day I could use that knowledge for something... 
   
But,

while we're at it... 

The direct wiring of the transformer is up to code even if not fed by GFI right?

Ummm No, technically everything connected to outside outlets needs to be protected by a GFI.  That said what you did will be fine just don't touch the transformer when it's wet.    Also GFI's in outdoor or damp settings should be of the new WR type. Basically the companies that make GFI's found out there they all fail after a short time outside due to corrosion from dampness and water so the WR ones are better sealed and have corrosion proof contacts.  On another side note I think I have found only one or two weather proof boxes that were exposed to water (rain, sprinkler, etc) that stayed dry inside. I often drill a tiny 1/8th to 1/4" hole in the bottom of the box to let water out unless the box is at or close to ground level. 

[Night Owl]

I did a little Googling and I fuond this on the Malibu Lighting website FAQ on transformers:

I do not have a Ground Fault Circuit Interrupter (GFCI) outlet outdoors. Can I use a regular outlet?
No. Per UL1838, the outlet must be GFCI. If not, the user must replace the outlet themselves or have an electrician do it. Also the outlet must be covered with an in-use weatherproof cover.

UL1838 is the UL standard for low voltage landscaping lighting systems.  Did your transformer originally have a plug attached to it?

[zwiller]

Of course it had a plug...  But how cool would plugging a cord in be. 

For the record, the gfi is feeding transformer primary. Not sure what the technical term is. 

[Night Owl]

If it had a plug on the end and you removed it, then I'm pretty sure that direct wiring up it to your electrical system is not in compliance with the electrical code, with or without the GFI.  I say this because the power cord was probably not designed or approved for direct connection to the house wiring. 

I had a GFI that kept tripping.  The foam gaskets on the outlet covers had decayed to the point that it wasn't keeping the water out.  I replaced the outlet and swapped out the cover with one that protects even with things plugged in.  I found out that these covers were required by the electrical code.   

[dudehenry3]

By code it should have a plug on it yes.It is in the NEC code .As a safety also known as a disconnect.You would not hard wire your vacuum in the house.