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 Post subject: Cut outs for Protection Device Settings for easy visibility
PostPosted: Fri May 30, 2014 12:46 pm 
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Joined: Tue Oct 09, 2012 5:00 pm
Posts: 53
Hi Friends,
On many switchgear, switchboards, and MCC the trip settings of power circuit breakers/static trip circuit breakers are easily visible on LV switchgear. However, many circuit breakers in switchboards have individual bolted cover keeping only the ON/OFF knob exposed. This makes extremely difficult to open the bolted cover and read the existing trip settings. We dress per NFPA 70E TABLE 130.7(C)(9) to collect the data and we suit down after removing the bolted cover to take picture/trip setting readings and suit up again to put it back. It was not easy, especially when we have multiple switchboards with many circuit breakers on it. I thought if we can leave a cut out on the trip settings so that the trip settings are clearly visible without having to open the bolted doors. In fact, at site I found some switchobards with cover cut-out on trip settings which many arc flash data collectors would appreciate. But many are still hidden with cover. With arc flash study being taken seriously, will there be a standard where the settings of the protection devices should be designed with cut outs on covers for clear visibility? On the MCC most of the motor circuit protector doors/buckets have defeatable door interlock and wasn't problematic to collect data.


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 Post subject: Re: Cut outs for Protection Device Settings for easy visibil
PostPosted: Fri May 30, 2014 2:35 pm 
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Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
Namgay Tshering wrote:
Hi Friends,
On many switchgear, switchboards, and MCC the trip settings of power circuit breakers/static trip circuit breakers are easily visible on LV switchgear. However, many circuit breakers in switchboards have individual bolted cover keeping only the ON/OFF knob exposed. This makes extremely difficult to open the bolted cover and read the existing trip settings. We dress per NFPA 70E TABLE 130.7(C)(9) to collect the data and we suit down after removing the bolted cover to take picture/trip setting readings and suit up again to put it back. It was not easy, especially when we have multiple switchboards with many circuit breakers on it. I thought if we can leave a cut out on the trip settings so that the trip settings are clearly visible without having to open the bolted doors. In fact, at site I found some switchobards with cover cut-out on trip settings which many arc flash data collectors would appreciate. But many are still hidden with cover. With arc flash study being taken seriously, will there be a standard where the settings of the protection devices should be designed with cut outs on covers for clear visibility? On the MCC most of the motor circuit protector doors/buckets have defeatable door interlock and wasn't problematic to collect data.


No.

If you leave the pots exposed so that anyone and everyone can fiddle with them, guess what happens? That is why they are typically covered up, as annoying as it is.

You are moving away from areas where everyone that has access would be required to be qualified (inside an MCC bucket, on switchgear that is in a locked room as per NEC) to areas that are out in the wide open such as 480 V panelboards where everyone from the floor sweeper to the engineer has ready access.

At the point that this happens, there is no point in doing an arc flash study anyways unless you just assume that all breakers are set at "Hi/Max", and there is no reason to open covers.

That being said I do agree that the door designs on a lot of panelboards leave a LOT to be desired. They flex a lot, and with only bolts to hold them on, there is a strong risk of accidentally dropping the door into the bus bars and causing an arc flash. I would hope that this design changes towards a safer design in the future such as by adding a hinge on one side to minimize the risk of dropping the door.


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 Post subject: Re: Cut outs for Protection Device Settings for easy visibil
PostPosted: Thu Oct 30, 2014 9:45 pm 

Joined: Thu Oct 30, 2014 9:44 pm
Posts: 1
thanks for sharing. good luck

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dany


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 Post subject: Re: Cut outs for Protection Device Settings for easy visibil
PostPosted: Fri Oct 31, 2014 5:58 am 
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Joined: Tue Nov 12, 2013 6:31 am
Posts: 238
Location: Port Huron, Michigan
Adding windows of appropriate material would probably give you much of what you want while satisfying much of PaulEngr's concerns.

Most of the equipment I have experienced has had hinged covers instead of bolted, which tends to improve the safety of opening the doors.


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