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I have only seen it once. It was a 120V dead short.....dont remember if it was to ground or neutral....and it was a 200 amp main....or fuse.....:vs_laugh:

****, I don't remember much do I :vs_laugh:
 

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I have only seen it once as well. I was called in to see why the 1600A main to the buiding tripped. A guy there told me there was construction going on in a suite, and someone tripped a breaker. I called a company to do the testing & calibrate
 

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A20 amp circuit breaker instantaneous can easily exceed 200 amps. An old breaker that is never exercised could trip at a MUCH higher value. A 1000 amp main with ground fault minimum setting is often 20% = 200 amps. Even if this place stays up on testing and servicing their main switchgear almost everyone ignores any breaker below 400 amps. They are much cheaper to replace than test. It all depends on how critical uninterrupted power is to their facility.
 

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I've heard this was possible but never seen it.

There's an electrical contractor that my older brother used to work for. Contractor used something similar to this, except has a switch to flick after plugging it in. My dad told me that it's possible to trip the main for a building using this. After reading this thread, I can see why.


Sent from my new phone. Autocorrect may have changed stuff.
 

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I've heard this was possible but never seen it.

There's an electrical contractor that my older brother used to work for. Contractor used something similar to this, except has a switch to flick after plugging it in. My dad told me that it's possible to trip the main for a building using this. After reading this thread, I can see why.


Sent from my new phone. Autocorrect may have changed stuff.
That would be a line to neutral short, so not as easy to trip a ground fault main with it. It could happen, but only if something else was wrong.
 

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If the short circuit was large enough and fast enough it could have been too much for the larger breaker protecting the 20amp also too much for the breaker feeding the panel. "selective coordination" is supposed to prevent this from happening. I've seen a branch circuit getcut during a remodel which in turn tripped a whole wing of a hospital.
 

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What is the voltage and amp of the main that tripped?

This makes a huge difference in how to troubleshoot.......
 

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I've seen a short in a dryer (240V/30A) trip the breaker on the pole servicing a little six unit strip mall.
 

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This is a standard case where the electrical engineer did not give intelligent settings for the Ground Fault Protection Relay and the installation electrician did . ot push for the correct settings. I'd bet the GFPE Relay is set at 100 or 200 amps, since a 20 amp CB can have instantaneous currents of 160 or more you exceeded the settings of the GFPE on the Main CB, or Bolted Pressure Switch.
 

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When I started working construction at our airport in 1995, we were told not to purposely short out a cct to find the breaker, we may have done that once or twice, because it would take down the whole Terminal Building. I didn't believe them until I saw it a couple of times. It won't happen now with all the new equipment but it sure would with the old FPE stuff. By the way, the main was a 13.8KV installed around 1975 and was well maintained and tested.


Tim.
 

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I've seen a short in a dryer (240V/30A) trip the breaker on the pole servicing a little six unit strip mall.
That is a coordination issue and/or defective CB or undersized Utility fuse.
 

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But why wouldn’t the branch circuit breaker trip first? Or the breaker feeding the lighting panel?
I had the same thing happen on a 30 amp circuit in a machine shop. I asked the in house Electrical Engineer and he said it was due to improper breaker coordination. Something to do with the interrupt rating of the breakers if I recall. The main was a 2000 amp non-GFCI and it tripped. It was a trippy situation to say the least. Lots of upset people. Delta Rocket nose cone on large vertical lathe and 2 Delta Rocket skins in the middle of a program with 3 large cutter coming to a instant stop. Lucky me nothing got damaged but it's spooky when it happens.
 

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I've heard this was possible but never seen it.

There's an electrical contractor that my older brother used to work for. Contractor used something similar to this, except has a switch to flick after plugging it in. My dad told me that it's possible to trip the main for a building using this. After reading this thread, I can see why.


Sent from my new phone. Autocorrect may have changed stuff.
I think you should add a 30 amp feed thew CB to the end of the cord, that way you would have some protection. Hopefully the 30 will out preform the 20. :vs_laugh:
 

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I've seen this three times -- in every case the Service was 1000A or more and GFI protected at the Main Breaker.

The trip is instantaneous -- believe me.

WHAM!
We see this 3-4 times a month, during demo, electrician tracing circuits by shorting, actual ground fault, bad GFCI relay or current sensor.
 
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