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Lightning strikes fry garage door photo eye

Posted by jdgt225innh (My Page) on
Fri, Jun 20, 08 at 18:19

Every year(no exaggeration) one of my photo eyes on my garage doors gets a shock from a nearby lighning strike, which of course kills it. Every year I have to replace the sensor. It's the same one every time. It took a few years and a few mother boards before I installed lightning suppressors. They seem to work because the mother boards are fine. Today I was out in my garage sitting in my lawn chair watching the storm go by and then BANG! For a second I didn't know where I was. I could actually taste the electricity. Luckily I was sitting in a plastic chair. Lighning struck right outside and I heard a POP down by the sensor that normally goes bad. Sure enough it is dead and the mount bolt is charred.

My question is, what can I do to prevent this annual event from happening, which is costing me $35.00 a whack? I tried putting electrical tape on the mount bolt. The bracket is mounted to the wall, sheetrock and wooden stud. I'm not sure where the charge is coming from. Could it be ledge? Rebar in the foundation/slab? Any recommendations would be much appreciated.

Dave


Follow-Up Postings:

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RE: Lightning strikes fry garage door photo eye

The only thing I can suggest you try is unplugging the unit when you know a storm is coming. I really don't think there is a thing you can do when lightning strikes that close. Running won't even help.


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RE: Lightning strikes fry garage door photo eye

The magnetic field that accompanies a bolt of lightning is very strong, and can induce voltage in runs of wire.
If the voltage is larger than the device can withstand it fails.
There are a number of ways to try and protect devices from the induced voltage, but even at $35 a pop it might not be worthwhile.

The simplest fix that might work is to use twisted pair wire for the connection to the sensor.
The twisting all by itself helps cancel out the magnetic coupling.
Next would be shielded twisted pair.
EMT would be even more shielding (but only if you use clamp connectors and NOT the set screw connectors).
Depending on the design of the device and the voltage you may even be able to place a voltage clamp near the sensor.
You need one that has a high enough voltage to not turn on from the regular operation, but turn on at a higher voltage that is still below the damage level.


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reRE: Lightning strikes fry garage door photo eye

"I could actually taste the electricity. Luckily I was sitting in a plastic chair."

The plastic chair will not insulate you from a lightning strike.
Get inside.


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RE: Lightning strikes fry garage door photo eye

Wow, you are lucky. Odd that the same components are affected, not the rest of the house. I like the em surge theory and was wondering myself if twisted pair would be a solution - you could just use cat 5 ethernet cable as a likely source of twisted pair, or even cat 3 phone cable.

I wonder if it's just induction/em surges or if you've actually had a strike on your house, in which case maybe lightning protection (sounds like you already have whole-house protectors, if not you should) and even lightning rod type stuff. Once out of vogue and oft the province of snake oil salesmen in country areas, they seem to be back in vogue, I've seen modern buildings with them (albeit rather stylised a la "Metropolis")


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RE: Lightning strikes fry garage door photo eye

I am having the same issue except my sensor hasn't failed. I am not sure if it is induced voltage or electricity coming through rebar in the slab or piping. The garage door frame is right on the slab. Should I ground the door frame or cut the bottom to get it off the slab?


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RE: Lightning strikes fry garage door photo eye

A coworker just had the house across the street from his hit for the second time, and once again it fried any computer equipment with a cable more than a few meters long, along with damaging his whole house sound system.

Unless the garage door frame is also connected to electronics any voltage induced is not going to bother anything.


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