Electrical Working Clearances

[adamscb]

In our plant there's an air-conditioning unit in one of our substation breaker rooms. The A/C unit runs on 120v, single-phase. On the other side of the room there is a row of 13.8kV circuit breakers.

The question I have is regarding electrical working clearances. I'm aware that the minimum required working distance increases as the voltage increases. Which voltage should I base my clearance distance off of? The 120v or the 13.8kV?

If I base my clearance off of 120v, then the minimum distance needed is 3 feet. If I base my clearance off of 13.8kV (~8kV line-to-neutral), then the minimum distance is 6 feet. Which one should I use?

 

[steve66]

You have to have the 6' clear in front of the 13.8KV gear. If you just use the 3' for the AC unit, you won't have that.

In effect, you use both clearances - making sure the AC unit has 3' clear in front of it, and making sure the 13.8KV equipment has 6' clear in front of it. Note that the clearances can be shared. Clear space is clear space - you don't have to dedicate it to one particular piece of equipment.

 

[kenman215]

Continuing on this topic, I just installed some switch gear in an electrical room located in the underground level of a parking garage. The floors of the building are supported by 16" × 12" columns which have a 9' × 9' × 6" deep capital at the ceiling. In the electrical room layout my PM created, the corner of a capital is only 4" off the face of the termination section of my gear. The gear sits on a 4" tall housekeeping pad and is 2" off of the ceiling. I told him that I was afraid of us getting jammed up on clearance issues, he said don't worry about it. Should I be worried? Opinions?

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[juz720]

Continuing on this topic, I just installed some switch gear in an electrical room located in the underground level of a parking garage. The floors of the building are supported by 16" × 12" columns which have a 9' × 9' × 6" deep capital at the ceiling. In the electrical room layout my PM created, the corner of a capital is only 4" off the face of the termination section of my gear. The gear sits on a 4" tall housekeeping pad and is 2" off of the ceiling. I told him that I was afraid of us getting jammed up on clearance issues, he said don't worry about it. Should I be worried? Opinions?

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I would've suggest consulting with you're local building permits office for certain specification.

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