Author Topic: Why is my circuit breaker tripping  (Read 259 times)

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Offline justinjja

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Why is my circuit breaker tripping
« on: January 11, 2017, 02:19:29 PM »
I'm trying to move 2 of my 6 Mining computers from my laundry room to my garage.
All 6 computers run fine when powered by a dryer socket (240v 30a)

According to my Killawatt, the 2 computers pull 1500W (0.99 PF) in my garage.
The whole garage, and only the garage is on a single 20A breaker (120V)
When I try to connect the computers via powerline adapter I trip my breaker within 1hr.
But if I unplug everything except the computers, and switch them to Wifi, the breaker never trips.

The breaker is just a standard 20A breaker.
The wall socket is a GFI (The gfi isn't tripping, the breaker is)

So it looks like, either a power line adapter, an AC line filter, or a power strip is tripping my breaker.
Which of those would make the most sense?

So far I have not had the breaker trip while opening/closing the 1/3hp garage door (W/ all the computers running too)

 

Online rstofer

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Re: Why is my circuit breaker tripping
« Reply #1 on: January 12, 2017, 04:18:17 AM »
It could very well be a defective breaker.  The fact that it takes an hour means it is tripping on Long Time current, not Instantaneous.  The breaker should be able to hold its rated current indefinitely but we use an 80% factor for maximum load.  At 120V, a 20A breaker should be able to handle 2400W and we derate that to 1920W.  So, your load need to be less than 1920W and it seems this is the case as long as I am reading the "2 computers pull 1500W" as the combined load.

Generally, molded case circuit breakers can carry an overcurrent for quite some time so even if you were running close to 1920W, the garage door motor running wouldn't last long enough to trip the loaded breaker.

So, change out the breaker and see what happens.  Also, look for a loose connection at the breaker because this extra heating is all it takes to make the breaker trip.

 

Offline turbotemp

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Re: Why is my circuit breaker tripping
« Reply #2 on: January 12, 2017, 04:38:29 AM »
So, check the draw on the breaker with a clamp meter.
 

Offline justinjja

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Re: Why is my circuit breaker tripping
« Reply #3 on: January 12, 2017, 05:29:58 PM »
Narrowed it down to a power strip. Not sure how that works.

My best guess is the circuit breaker is fast, and the power strip is slow.
The power strip (15A rated) was close enough to briefly disconnect then reconnect the load, and that caused a power surge that tripped the 20a circuit breaker?

Sounds a little out there, but that's all I can think of.
 


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