REPETITIVE RESETTING TRIPPED CIRCUIT BREAKERS

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Electron_Sam78

Electron_Sam78

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Palm Bay, FL
Hey all I'm putting together a small shop safety briefing about repetitive resetting of tripped circuit breakers. I have OSHA's CFR 1910.334(b)(2) which prohibits it but does anyone have any other resources such as examples of repetitive closing without troubleshooting the circuit gone wrong? OSHA documented cases would be good.

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What type and size?


I will say this, reclosing breakers, especially those over 100amps is about the most asinine thing a person can do. Big John & Zog will explain it better then me.
 
Electron_Sam78 said:
Didn't have any type or size in mind. Just in general

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FWIW under UL testing molded case breakers are only required to endure a few short circuits. So closing a breaker repeatedly into a fault (more then once) leaves a lot to be desired. As for large circuit breakers the breaker itself may explode re-closing into a fault, assuming the fault itself wont be a problem.


Bottom line, when you approach a tripped breaker, you never re-close without finding what tripped it first. Small 15-30amp breakesr are probably ok taking a single shot, but a 2000amp breaker is suicide.
 
An electrician in my area got seriously hurt (life changing) working on high voltage lines for the railroad. Apparently the crew was at the wrong location. He got hit and the breaker tripped. Then someone reset it and he got hit again. They said it was railroad policy to reset a tripped breaker one time, might be a squirrel on the line.
 
GerryB said:
An electrician in my area got seriously hurt (life changing) working on high voltage lines for the railroad. Apparently the crew was at the wrong location. He got hit and the breaker tripped. Then someone reset it and he got hit again. They said it was railroad policy to reset a tripped breaker one time, might be a squirrel on the line.
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Thats where auto-reclose relays come in. And breakers that are designed for it.
 
Electron_Sam78 said:
Hey all I'm putting together a small shop safety briefing about repetitive resetting of tripped circuit breakers. I have OSHA's CFR 1910.334(b)(2) which prohibits it but does anyone have any other resources such as examples of repetitive closing without troubleshooting the circuit gone wrong? OSHA documented cases would be good.
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Anecdotally, I've been involved in several failures where guys have screwed that up. Thankfully, I've never had anyone get hurt from it, but seen some very serious equipment damage as a result. Had one guy reclose into a failure a half-dozen times and it blew apart a submarine transmission cable in as many places; every time he reclosed a different splice section failed. He finally stopped when "I saw fire come out of the switchgear." Yeah, that's a good stopping point, buddy: I believe the total repair and lost generation costs for that were in the 7 figures.

As far as actual documentation, you might get lucky searching OSHAs accident statistics. Here's an EC&M article that documents a fire caused by improper reclosing.
 
Electron_Sam78 said:
Hey all I'm putting together a small shop safety briefing about repetitive resetting of tripped circuit breakers. I have OSHA's CFR 1910.334(b)(2) which prohibits it but does anyone have any other resources such as examples of repetitive closing without troubleshooting the circuit gone wrong? OSHA documented cases would be good.

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I think at some point is is anecdotal. People either get it or they don't. Don't stand on the top of a ladder, don't leave a hole unattended, don't speed, don't work too close to the edge. For an employee perspective, at some point you need to just explain minimally the issue and tell them, it is because you said so and they will get written up if they fail to obey.
 
The are UL 489 testing requirements which are eye openers. Breasker's are very robust.
But the repetedly resetting and closing a breakers is the result of lack of training and unqualified people.
Breakers either trip thermally because of heat or instantaneously because of a short circuit.
It is very difficult to determine a cause of trip if yu ou get there after try he fact. Breasker's that trip thermally have to cool of a bit before th hey casn be reset/latched as nd closed, that is if you are standing there when it trips. If you get there later then it has most likely cooled of already and can be reset.
A breakers that has tripped magnetically can be reset/latched and closed immediately. So is you get there after the fact there is no real eay to determine if the breaker tripped because of asn overload of short circuit/fault. If you are sdtasnding there at the time of the event it is much easier to respond to a cause of trip.
Tith an overload, a breaker with take some time to trip derlendent upon the magnitude of the intended overload. The breaker after gets wsarm and the thermal element must be given time to cool before tty he breaker casn be reset/latched and closed. This is not dangerous except there must be consideration as to what icausing the v
 
well, you cant really troubleshoot them all, sometimes the issue is poco and you cant test for it unless you have some nifty gear, which i bought to shove data in poco face so they would do something to fix the issue.

as example, gfci's are very sensitive to ring wave spikes. i know, i had the issue, darn poco and old utility infrastructure, ring spikes from local plant that is heavy on electric.
so this might be one of those caveats you talk about.
 
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