Working Space Requirements

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WaterRecInspector

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Hello forum!

I am inspecting an area that contains several individually cooled 480V VFD cabinets. The (4) cabinets are being placed on an equipment pad in the center of a process building. The arrangement is laid out so that there are 2 sets of back to back cabinets, and in the center of the 2 groups, 2 of the cabinets face each other.... basically creating "Condition 3" on Table 110.26(A)(1), so since both opposing cabinets operate at 480v, there is a working space requirement of 4 feet.

This is where I need help... Both opposing VFD cabinets have double swinging doors. Are these doors allowed to encroach upon the 4 foot working space of the opposite cabinet, or does spacing need to be such that the doors stay out of the working space? I.e. Swing of the door plus 4 foot.

Also keep in mind that the doors swing beyond 90 degrees, effectively shortening their amount of encroachment. (not sure if that matters).

Any help/opinions.
 
The working space begins at the front face of the enclosure. So if there is at least 4 feet of space between the two enclosures, the requirement is met. You obviously know where to find the table that gives the working space distances. Look at the sentence that appears immediately above that table.

Welcome to the forum.
 
WaterRecInspector said:
Hello forum!

I am inspecting an area that contains several individually cooled 480V VFD cabinets. The (4) cabinets are being placed on an equipment pad in the center of a process building. The arrangement is laid out so that there are 2 sets of back to back cabinets, and in the center of the 2 groups, 2 of the cabinets face each other.... basically creating "Condition 3" on Table 110.26(A)(1), so since both opposing cabinets operate at 480v, there is a working space requirement of 4 feet.

This is where I need help... Both opposing VFD cabinets have double swinging doors. Are these doors allowed to encroach upon the 4 foot working space of the opposite cabinet, or does spacing need to be such that the doors stay out of the working space? I.e. Swing of the door plus 4 foot.

Also keep in mind that the doors swing beyond 90 degrees, effectively shortening their amount of encroachment. (not sure if that matters).

Any help/opinions.
Click to expand...

Doors are allowed to encroach upon the work space in the open position, provided that they all have the ability to open at least 90 degrees, and that the distance between closed doors meets or exceeds the depth required by 110.26. The chance that you absolutely need to service both at once is rare. If it is likely that you will need to service simultaneously, then while it may meet the NEC, it is poor project planning if doors have to encroach upon working space for simultaneously serviced equipment in the "common aisle" condition.
 
Thanks For Your Time Guys.

I guess this is one of those areas where the NEC could be improved a bit (I say that with hesitation, due to a fear of over-complication).

My concern is that in a situation where all 4 doors are open, and an individual is working in the gear, it will create an arc-flash scenario with more potential for injury. Not that anyone should be hot working in this situation... but humans sometimes make bad decisions. :)

:thumbsup: I was aware that the front of the panel is where the distance begins, just not sure whether or not the opposite door is allowed to swing into this space.

Thanks for the input!
 
Carultch said:
Doors are allowed to encroach upon the work space in the open position, provided that they all have the ability to open at least 90 degrees, and that the distance between closed doors meets or exceeds the depth required by 110.26. The chance that you absolutely need to service both at once is rare. If it is likely that you will need to service simultaneously, then while it may meet the NEC, it is poor project planning if doors have to encroach upon working space for simultaneously serviced equipment in the "common aisle" condition.
Click to expand...


I agree 100% with the bad engineering comment.

I have worked in the trade long enough, however, to rule out the possibility of a maintenance electrician opening both cabinets at once.

Thanks for the input. Have a great day. :)
 
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