turning on a cb is it safe ?

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jimbo123

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Rescently was instructed to wire a motor 230 volt to a 2 pole breaker into a 230 volt panel. The oringinal motor was a 120v motor controled automaticly. The 230v motor was install on temp bases because of a delivery problem and had to be controled by a worker turning on the cb evry hour or so till new motor arrived in less than 12 hrs.
The wiring was complient to nec but the operator who had to turn cb on claimed it is unsafe to turn cb on . The panel was closed with both the dead front and outside panel cover nothing exposed except the cb handle to 20 amp cb motor was 3/4 hp unit. Operator was instructed what to do and when, he said he was fine with that . One of his coworkers was not happy and complained its unsafe.
Is he right about it being unsafe to operate cb ?
 
I guess i meant to say " can he operate the breaker without violating any rules in 70e ?" does he have to be QW ? I don't see anything in the eewp.
 
T130.7(C)(9) 2009 70E lists circuit breaker or fused switch operation with covers on for panelboards rated 240V and below as;

Hazard/Risk Category 0
 
jimbo123 said:
I guess i meant to say " can he operate the breaker without violating any rules in 70e ?" does he have to be QW ? I don't see anything in the eewp.
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Any one can become trained and therefore be a QW for any specific task, being an electrician is not a requirement of 70E. It is up to the company to create and implement the requirements for the tasks their QW's perform.
 
Based on the description I would say that it is safe to turn on the breaker.
After all there are millions of SWD rated breakers in service and contriling lighting all the time by the breaker.

What I would be concerned with is the lack of a motor starter and OL protection.
 
tkb said:
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What I would be concerned with is the lack of a motor starter and OL protection.
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3/4HP 230V, single phase motor, probably integral protection. But it never hurts to question it.

To the original point, I too think that if there were a serious hazard to turning on small branch breakers in 240V lighting and distribution panels, there would cease to be "SWD" or "HID" ratings on breakers. All those MILLIONS of little breakers would need remote operators of one sort or another.
 
It's ironic that, as this thread debates an operation that is performed by the general population millions of times each day, without mishap .... that we have another thread right now where someone asserts that it is safe to open up live transformers.

I would say that panels are designed for the safe operation of the breakers without there being any need for any additional protective measures. Sure, bad things might happen ... just as bad things might happen on your drive to work.

As for use as motor controllers ... well, breakers do have horsepower ratings. What, besides motors, has horsepower ratings?
 
renosteinke said:
It's ironic that, as this thread debates an operation that is performed by the general population millions of times each day, without mishap .... that we have another thread right now where someone asserts that it is safe to open up live transformers.

I would say that panels are designed for the safe operation of the breakers without there being any need for any additional protective measures. Sure, bad things might happen ... just as bad things might happen on your drive to work.

As for use as motor controllers ... well, breakers do have horsepower ratings. What, besides motors, has horsepower ratings?
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The debate is raging all over - in NFPA 70E workgroup, IEEE1584, etc - as to what actual hazard 208/240V circuits represents. More importantly; how to determine that easily. Arc-flash science, at this point, is like global warming science. The rules had been 'decreed' by force, before the actual hazard was validated. Calcualtion formulas were created and as industry and academia is trying to empirically validate those calcualtions they're getting weird, contradictory and inconsistent data. Evidently there is a lot more to it. (Ex. it matters if you have copper OR aluminum involved, they will produce different level of arch-flash energy conversion.)

The ciruit breaker is NOT designed to be used as a controller. While switching duty breakers are investigated for turing lights on/off, that being a low switching duty, motor control is an entirely different area. CB contacts electrical life measured in the 10^4, while contactors 10^7. CB's are designed for fault level current interruption that is not an expected to be a frequent occurence, and contactors are designed for load switching and limited overload, but not fault, interruption.
 
I think the worker may be right in one aspect:Fault level.Is that breaker's interrupting (making) capacity above the expected fault level ? May be his hesitation was based on this instinctively.This may be checked.
 
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T.M.Haja Sahib said:
I think the worker may be right in one aspect:Fault level.Is that breaker's interrupting (making) capacity above the expected fault level ? May be his hesitation was based on this instinctively.This may be checked.
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If you look at post #3 you will see the concern is about being a "qualified worker" under NFPA70E, and not an issue with the application of the equipment.
 
jim dungar said:
If you look at post #3 you will see the concern is about being a "qualified worker" under NFPA70E, and not an issue with the application of the equipment.
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From the title of thread and many of other posts in this thread,it seemed relevant to me to highlight any issue with the application of the equipment.
 
The point about the equipment being applied correctly is valid, but it is not what the original question intended to ask.

This is an example of a thread straying but still being a relevant, particularly since the OP has not participated in the recent discussion points.
 
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