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Nearby Lightning causes only one GFI breaker to trip.

Posted by windslam (My Page) on
Thu, Sep 24, 09 at 21:28

I have a sub-panel in my garage which feeds all the lights and receptacles in the garage (detached). All of the breakers in the panel are GFI. One of the breakers feeds the 2 garage door openers only. Every time there is an electrical storm, the garage door opener GFI breaker trips if there is a a lot of lightning activity. The none of the other breakers trip, only the one for the 2 door openers trip. Any ideas?

The doors are Clopay steel doors along with the associated brackets and guides. Is it possible the doors build a static charge and maybe should be grounded to discharge the static?

I had a situation a few years ago when lightning struck nearby, the obstruction sensors actually blew apart and the circuit board in the opener fried. I've since put individual surge protectors on the openers and haven't had that problem again, just the tripping breaker.

Thanks


Follow-Up Postings:

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RE: Nearby Lightning causes only one GFI breaker to trip.

It could be as simple as the opener circuits are longer and further off the ground surface, allowing for higher coupling in to the lines, or the GFCI device itself being more exposed.

The electric field drives the strike from cloud to earth, but the large currents involved once current flows in the strike generate vary large magnetic fields.

These fields induce currents in any conductor they intersect with.

It does not matter if you have a static magnetic field and a moving conductor, or a varying magnetic field an a fixed conductor. A voltage is induced in the conductor based on the magnetic field strength, rate of change, and orientation of the conductor relative to the field.

If the GFCI device itself is in the magnetic field it can have transients induced in its own circuitry, independent of anything in any wires hooked to it.

The magnetic field could even couple into the magnetic pickup in the GFCI and cause the electronics to be saturated briefly and not operate correctly.

Since GFCIs trip at around 0.005 amps (5 milliamps) of current difference sensed using a magnetic pickup (a toroid) between the hot and neutral they are very sensitive.


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RE: Nearby Lightning causes only one GFI breaker to trip.

Why not replace the breaker with a non-GFI? As long as the GDO receptacles are not readily accessible (i.e., on the ceiling) GFI is not required for the circuit. As an added precaution, make sure nothing else can be plugged in to those receptacles, such as an extension cord to power a device that could be used where GFI protection would be needed. If there is a duplex receptacle at each GDO, replace with a single receptacle.


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RE: Nearby Lightning causes only one GFI breaker to trip.

Thanks for the excellent feed back!!!!

HRAJOTTE,
I could change the breaker since the receptacles are ceiling mounted. I wanted to make sure there wasn't another problem, like the doors needing to be grounded or something similar. If it's a nuisance issue as BRICKEYEE indicates, I can live with it since I like the extra safety a GFI provides. We get pretty frequent electrical storms in summer and I just wanted to make sure I wasn't inviting a lightning strike or, to be sure nothing was amiss.


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RE: Nearby Lightning causes only one GFI breaker to trip.

Also, some GFCIs don't have the same service life as a regular receptacle and become less reliable or fail after a number of years. I've had several that were tripping out more-and-more frequently, and when I replaced them with new GFCIs that fixed the problem.


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RE: Nearby Lightning causes only one GFI breaker to trip.

Thanks for the input guys.

Come to think of it, that breaker was in there when the sensors blew out and it could have been weakened by that surge. I think I'll replace the GFI and keep an eye on it, the GE's are inexpensive enough. I know breakers weaken with consistent trips and this one has done it about 15 times during various storms. If it's still a problem, I'll go with a regular breaker.


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