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irrig8r
12-15-2011, 04:39 PM
I have a customer for whom I installed four Kichler 15732 LED uplights
in his yard August 2010.

He is happy with the lights except that (coincidentally I think), his
GFI trips intermittently.

I checked the system for shorts and couldn't find any. It's a 10 year
old Unique transformer with a fuse, and the fuse does not blow. It's
just the GFI tripping.

I concluded that the had to be either the GFI itself, the line voltage
side of the transformer, or maybe some other device on the same
circuit with a big power demand turning on at the same times as the
lights.

I think what I am going to do is take a spare transformer over and
temporarily replace his (I have a Vista MT on hand I think.)

What would you do? What about the notion of something else on the
circuit that turns on at night? He doesn't seem to know what else is on it.

irrig8r
12-15-2011, 04:55 PM
Correction: I was *able to* sort them out only by....

One more thing I should add: The new fixtures were on a new cable run, #12/2 and only Ace connectors used on that run.

Richie@
12-15-2011, 05:06 PM
Does the circuit breaker in the house electrical panel also trip , if not then it is more than likely related to the GFCI.

It could be moisture or loose connections on the GFCI or within the transformer , also if the GFCI doesn't have whats called an In use device cover I would put one of those on , you can get one at home depot for around $ 9 just ask for an in use bubble cover for a GFCI.

AOLP
12-15-2011, 06:55 PM
I have a customer for whom I installed four Kichler 15732 LED uplights
in his yard August 2010.

He is happy with the lights except that (coincidentally I think), his
GFI trips intermittently.

I checked the system for shorts and couldn't find any. It's a 10 year
old Unique transformer with a fuse, and the fuse does not blow. It's
just the GFI tripping.

I concluded that the had to be either the GFI itself, the line voltage
side of the transformer, or maybe some other device on the same
circuit with a big power demand turning on at the same times as the
lights.

I think what I am going to do is take a spare transformer over and
temporarily replace his (I have a Vista MT on hand I think.)

What would you do? What about the notion of something else on the
circuit that turns on at night? He doesn't seem to know what else is on it.

first off, I am going to guess u have an in use cover in place. why a ten year old unique transformer? Was it there before and u added to it? did u install it new and its been in your shop for ten years? Answer this question and we'll trouble shoot on.

steveparrott
12-15-2011, 07:01 PM
Nearly all cases like this are caused by problems with the GFI itself - usually moisture penetration. It only takes a thin coating of moisture on the plastic at the plug end (between hot or neutral blade and ground pin) to create enough current differential to trip the GFI. Drying the plug and the face of the outlet and having a good in-use cover could solve the problem from this cause.

Such moisture problems often arise with very wet weather or high humidity combined with cool nights.

The second most likely cause is a faulty GFI - they sometimes need to be replaced.

A transformer problem is possible but unlikely - there would need to be current flowing from neutral or hot to ground. Only possible if a wire has come loose and is contacting the cabinet or an energized conductor. (It is a very old transformer!) If this is the problem - be very careful - a 120-v energized cabinet is bad news.

A short circuit in a fixture is highly unlikely to trip a GFCI since both the hot and neutral secondaries are isolated from hot and neutral on the primary. The secondary neutral, on the other hand, is connected to the ground and shared with the primary ground. So, in a scenario where a short has occurred in a fixture, there may be current flowing to ground, but I don't think the GFCI would trip - it should still see a balance between the primary neutral and hot - since those are not connected to the secondary. (I could be wrong about this.)

emby
12-15-2011, 09:03 PM
GFCI (Ground Fault Circuit Interruptor)

A GFCI receptacle is designed to prevent electrical shock. This device constantly monitors the current flow in the hot and neutral conductors.

The current in the hot and neutral conductors should match. If the current flow doesn't match, the device disconnects itself and any receptacles it protects from the electrical source.

Because the device does not actually check the ground current, it can be installed without a ground wire. A GFCI wired in this manner, or any receptacles protected by it, is required to be marked "NO EQUIPMENT GROUND" and is an allowable method of changing two-wire ungrounded receptacles to three-wire grounding receptacles.

Change the GFCI first, then if it still is tripping inspect the cord on the transformer really well for bite marks or damage.

Ken

RLI Electric
12-15-2011, 10:01 PM
It used to be a GFI had a shelf life of 6 to 7 years. That is of course a generalization. It is highly likely that if the system is 10 years old that the gfi can be that old or older. I concur with everyone, change the gfi.

Steve Atkinson
12-15-2011, 11:42 PM
Hi Gregg,

Today I hosted a workshop with Shawn Knudson, the Vista rep in Oregon, and during the discussion, this very topic came up. He said electricians will always blame the GFCI but it may be that the transformer is creating such a large inrush of current that the GFCI naturally trips off.

His recommendation is to try running a temporary extension cord to the transformer from a receptacle and circuit that is farther away from the transformer. If that circuit breaker trips off when the transformer activates, it's a safe bet that the transformer is suspect. If not, it may be the GFCI is weak. He also suggested that one should use a, I believe he said, a MAC Breaker. A heavy-duty product that you will not find at HD or Lowes, so may have to go to an electrical supply store.

Hope this helps.

The Lighting Geek
12-16-2011, 12:14 AM
It has been my experience that the GFCI is bad. I would replace it with a new bubble cover and 90% of the time problem solved.

Is the transformer fully loaded? Usually I don't have in rush issues unless it is close to max. I have had issues if the line between the GFCI and the breaker is short, less than 20' or so.

If you have a bad LED, or a short, it would show up in your amp probe reading of the home runs.

Lite4
12-16-2011, 09:52 AM
I have had some inrush issues in the past (Trans within 10 of the panel by wire distance). I added a 100' loop of UF and buried it (problem solved).

irrig8r
12-16-2011, 10:58 PM
So,

Seems like the consensus is the GFI is bad. Which is exactly why I called out an electrician to replace it back in early November. When I emailed the customer to ask why he hadn't paid the bill yet he said he is still experiencing the same intermittent problem.

The only reason I used the 10 y.o. transformer was that it was there already and I only added four fixtures, and it way under capacity to begin with.

There is and has been a good in-use cover. I haven't actually been there since early November though, so I will swing by and see if he may have plugged Christmas lights in to the same outlet and propped the cover open. (I have seen that before.)

Don't know where the breaker is. In a closet in the house I think. Probably more than 20 ft. away.

I used the "amp clamp" of my Greenlee multimeter and didn't find a short. And as I mentioned to him, wouldn't the fuse have blown if there had been a short on the LV side?

irrig8r
12-16-2011, 11:28 PM
Trying to attach some photos... one showing a 4.9 A reading, the other showing 0.9 A.

These are the only two runs in the front yard. Customer ordered and changed out all the lamps on the 4.9 run himself... to retrofit LEDs. The smaller amperage run is the Kichler integral LED accent lights.

In other words, before he changed them out over a year ago there was more current drawn than now.

Last picture is the label in the transformer. Faded yellow label was stuck over the brighter colored one but the sticky backing wore out and it fell off.

Faded one seems to say 3 A, one underneath said 9.33. Just weird.

Hmmm...two of three file uploads failed...

irrig8r
12-16-2011, 11:46 PM
https://mail.google.com/mail/?ui=2&ik=b0344a34fc&view=att&th=13449f7fc2b16b64&attid=0.1&disp=thd&realattid=1388409925412061184-1&zw

So, the faded label covered up bright one until it fell off. Kinda looks like moisture getting in there too. Maybe just condensation.


https://mail.google.com/mail/?ui=2&ik=b0344a34fc&view=att&th=13449f37ced260df&attid=0.1&disp=thd&realattid=1388409605972819968-1&zw

emby
12-17-2011, 12:22 PM
https://mail.google.com/mail/?ui=2&ik=b0344a34fc&view=att&th=13449f7fc2b16b64&attid=0.1&disp=thd&realattid=1388409925412061184-1&zw

So, the faded label covered up bright one until it fell off. Kinda looks like moisture getting in there too. Maybe just condensation.


https://mail.google.com/mail/?ui=2&ik=b0344a34fc&view=att&th=13449f37ced260df&attid=0.1&disp=thd&realattid=1388409605972819968-1&zw

Well, two options I would think...ask the electrician if there are any wires attached to the GFCI receptacle on the load side. If so then you will have to trace those wires and most likely you will find your problem. If nothing is on the load side then it also is possible that there could be another GFCI device on that same circuit in which case having two GFCI devices on the the same circuit will cause nuisance trips. If all that is good then try changing the transformer as it could have a loose connection or a bad component that is causing this. Let us know how you make out.

Ken
Posted via Mobile Device

irrig8r
12-19-2011, 10:51 AM
Well, two options I would think...ask the electrician if there are any wires attached to the GFCI receptacle on the load side. If so then you will have to trace those wires and most likely you will find your problem. If nothing is on the load side then it also is possible that there could be another GFCI device on that same circuit in which case having two GFCI devices on the the same circuit will cause nuisance trips. If all that is good then try changing the transformer as it could have a loose connection or a bad component that is causing this. Let us know how you make out.

Ken
Posted via Mobile Device

Thanks Ken. Going to call the electrician about that. Also going to try a "loaner" TF.

irrig8r
12-21-2011, 01:48 PM
The electrician says there was nothing wired to the load side of the GFCI. Time to find what else is on the circuit. If the backyard lights are on it too then I'm going to tell the client we need to ditch the GFCIs and replace them with a single GFCI breaker in the panel.

Of course that means having to go to the panel to reset it when it trips, but I'm trying to get it to where it doesn't trip without cause.