GFCI Tripping during dimming

[Bjpatter]

Hi all,

 

I am in year 3 of putting on a show.  First year I never had a problem.  Last year started having GFCI trips (in a new house) but assumed that is water getting into bad places and have worked to resolve that (child protection covers on all open plugs, all connections off the ground, some connections routed through large storage bins that are elevated w/ drain holes).  I also changed out my GFCI's to rule them out.

 

However, I kept tripping a GFCI when songs were winding down (and lights were dimming - right at the end the GFCI would trip right when the lights finally went out).  On the circuit we have 56 strands of LED lights.  The breaker is a 20A dedicated breaker to the controller, channels 1-8.  If I disconnect 3 sets of lights, and only have 53 strands going, there was no trip.  It doesn't matter what 3 strands are disconnected, just needs to be 3.  Lots of frustration in troubleshooting this thinking I found a channel causing the trip until I learned it didn't matter where the 3 strands were removed.  And again, only when lights are dimming and are just about to go out.  Everything was bone dry and no rain or water was present.

I changed the dimming setting to be either fully on or off, and when I run the show now with all strands of lights connected there are no issues.  

There are a few songs that are very heavy with dimming sequences throughout them, so not having that feature turned on makes those songs not quite as enjoyable.

Wondering if anyone has seen this before with a GFCI tripping only when lights are dimming and are going out.

 

Thanks for any insight you may have!

[Orville]

That's interesting.  I've used LED's and dimming for years {older V2 CTB16PC Controllers} and in all my years, I've never had an issue like that.  But I never had that many LED strands on a single channel either, so  I'm not sure if that many could cause some type of possible amperage?/voltage? over imbalance/overload to create this when dimming them.

Hopefully someone that has used that many strands will chime in and let us know.  I'd be very interested to know why this occurring myself.   Especially since you changed out the GFCI's to new ones, then again, always a chance a bad batch of GFCI's got through that may have some kind of issue,

But I do find this occurrence very odd, especially since they are all LED strands.

[k6ccc]

Are at least some of these on metal tomato cages that are on the ground?

 

[TheDucks]

Your GFCI is failing (lost its noise immunity).  A few years back, I would have one trip when I turned OFF the bathroom fan. 2 points: 1) the fan was not on that GFCI. 2) the fan was not even on that BRANCH (breaker). The only thing in common, they were for things in the bathroom (the GFCI was for bathroom outlets only). The Green-Ground was good. The L and N supported a hair 1500W blower

[Bjpatter]

@k6ccc no metal tomato cages. Most of this is on PVC. I have 16 strands that are zip tied down to metal hooks that are screwed into a wood block (no metal hooks touching anything else metal). Wood block is at the top of a flag pole and bottom of strands are raised off the ground on plastic stakes. The metal hook in the wood is the only metal being contacted. 
 

@Orville I know it is a lot of strands and think if I was overloading the circuit then when all lights were on I would still have this problem. The dimming piece of it is very odd. 
 

@TheDucks I don’t think the GFCI is failing. I believe it is working. I changed it out the same time with three others. While replacing this one I replaced three other dedicated breakers from the no label builder grade breakers to these. And the same breaker still pops during dimming so I don’t think the odds favor a bad GFCI when I replaced four at once and somehow put a new/bad breaker in the same slot

[TheDucks]

2 hours ago, Bjpatter said:

@TheDucks I don’t think the GFCI is failing. I believe it is working. I changed it out the same time with three others. While replacing this one I replaced three other dedicated breakers from the no label builder grade breakers to these. And the same breaker still pops during dimming so I don’t think the odds favor a bad GFCI when I replaced four at once and somehow put a new/bad breaker in the same slot

Oh. A GFCI Breaker.  Many of us use GFCI outlets.

1) They cost less (~$10@ in 3 packs)

2) you can use multiples (loads permitting) on the same branch, so that when 1 trips, the other outlet still stay on (and are protected)

Dimming causes EMI.  (noise rejection needs)

Extension cords are big antennas for ESD (Lightning strike ground effects).  The strike does not have to hit your stuff. The HUGE currents in the earth can induce a major spike.

The other mode is simply repeated (over time) pulses that are just within limits.  (There is a reason power supplies now use Low ESR Capacitors. The get lots of higher current pulses than the old 120Hz filters of the vacuum tube era)