Light switch pop

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Old 10-30-17, 07:59 AM
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Light switch pop

I have new retail construction I'm doing and I have done a lot of wiring before. I have never run into an issue like this before. I have 15 led 2x4 lights in drop ceiling. They are wired to a single pole switch. The problem I'm running into is the switch pops sometimes when I turn on the lights and sometimes after 10 mins and then sometimes remain on all day. I checked all connections and nothing seems loose. I did ohm and continuity test and neither shows lines are shorting. At the break with all lights turned on I'm getting 5.12 amp draw which times 120v is 615 load. No where near the threshold on a 20amp breaker. Nothing else is on the breaker besides the 15 lights

what else can I troubleshoot before calling an electrician? Are led known to cause short circuits out of the box?
 
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Old 10-30-17, 08:27 AM
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You mean the switch actually makes popping noises or it trips the breaker? If the switch is making popping noise it's either bad an needs to be replaced or something in the box is loose or a skinned wire is touching the metal box. Maybe a metal cable is crimped into the wire insulation.

Since it's retail space, sure it's all 120V and not 277V?

My next thought would be it sounds like something is overheating if it runs 10 minutes before tripping, I'd probably look there next if the other ideas don't pan out.
 
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Old 10-30-17, 08:28 AM
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Ground and neutral are bonded
 
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Old 10-30-17, 08:33 AM
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The light switch pops and trips the breaker at the same time. The lights are on 120v. I replaced the switch with a new one and get similar results. I checked if the wire was okay and it looks fine at the switch box. Nothing is loose and I even taped the switch.

could it be a bad led fixture ? It's so random that sometimes no pop all day and other tines it pops when you first turn it on
 
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Old 10-30-17, 09:52 AM
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Ground and neutral are bonded
That doesn't positively signify 120v.
A 277v circuit also has it's ground and neutral connected at the main panel.
277v is very common in commercial and is used a lot for lighting circuits.

It would better if you used "trip" if the breaker trips. Pop can mean a popping sound at the switch.

If you have a circuit tripping..... there is a short. I have never seen a switch cause a short. A switch can make popping sounds or arcing sounds. Anything can cause that short..... two wires skinned back too far and touching.... hot wire touching the metal light frame..... a bad LED driver.
 
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Old 10-30-17, 10:16 AM
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Disconnect one light fixture at a time till it stops doing it.
 
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Old 10-30-17, 04:38 PM
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I know it's 120v because this is a subpage with only lower 120v. The other panel is 3 phase. To clarify, the switch pops which I believe is causing the breaker to trip because it senses the arc. The issue is like today I had the lights on for 8+ hours and nothing happened even after trying to replicate the issue.

I too believe it might be the led light but which one? Is there a way to test or do I have to remove all of them? One by one wouldn't work because they remain working for hours without any issues.
 
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Old 10-30-17, 06:20 PM
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I believe is causing the breaker to trip because it senses the arc.
.
Breakers so not trip on arcing except for AFCI breakers. If this is a retail space, I would doubt they are AFCI breakers unless it is a dwelling. Standard breakers only trip on overload.

The other panel is 3 phase.
3 phase panels are also 120 volts to ground/neutral, Except a high leg delta.

It is normal for a switch to pop when making or breaking a circuit with a load on the circuit. The breaker tripping is not normal. You likely have a loose or pinched wire some place that is causing a short and tripping the breaker.

Best way to troubleshoot is to disconnect half the circuit and then work your way further down the circuit if the breaker holds fine, or further back if it still trips.

What is the wiring method you are using?
 
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Old 10-30-17, 09:54 PM
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All of the lights were connected using the quick connectors often found in recessed and 2x4 light fixtures. They are wired in series using flex. A friend helped make the flex cable connectors so I will have to take it all apart and inspect. Maybe go as far as return fixtures and get a different brand.
 
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Old 10-30-17, 10:04 PM
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They are wired in series using flex.
Did you mean parallel? .
 
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Old 10-31-17, 09:08 AM
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Sorry they are in parallel
 
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Old 10-31-17, 10:08 AM
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It could be the metal jacket of the MC or AC flex cutting into a wire. Common problem if the reds aren't installed all the way or a clamp is too tight. Maybe if you have a thermometer laser gun you could check the LED drivers and see if one is running hotter than the others -- could signal it's the one going bad.
 
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