NEC Table 110.34 (A)

[slo7682]

NEC Table 110.34(A) - If I have face to face deadfront switchgear can the minimum working clearance be 6 feet by Condition 2 or does it have to be 9 feet by Condition 3 for 15 KV? I see deadfront as being gaurded as provided by Condition 1 and thus I could be 5 feet. Right.

 

[bphgravity]

Re: NEC Table 110.34 (A)

Unless the deadfront is made of plastic, I don't believe Condition 1 can be used. I believe Condition 3 must be achieved per your description.

 

[rbalex]

Re: NEC Table 110.34 (A)

It is Condition 3. The ?hint,? as it were, is found in :

110.34 Work Space and Guarding. Except as elsewhere required or permitted in this Code, the minimum clear working space in the direction of access to live parts of electrical equipment shall not be less than specified in Table 110.34(A). Distances shall be measured from the live parts, if such are exposed, or from the enclosure front or opening if such are enclosed.

However, if you are referring to a 15kV nominal system it is probably covered by line 2 in the Table (2501 ? 9000V to ground) unless it is an ungrounded system.

 

[charlie b]

Re: NEC Table 110.34 (A)

Just for my own curiosity, is there a way to take credit for some type of administrative controls to prohibit working on both sides at the same time? If so, can we use Condition 2? This question would apply to 110.26 as well.

 

[rbalex]

Re: NEC Table 110.34 (A)

Sometimes for low voltage see 110.26(1)(c):

(c) Existing Buildings. In existing buildings where electrical equipment is being replaced, Condition 2 working clearance shall be permitted between dead-front switchboards, panelboards, or motor control centers located across the aisle from each other where conditions of maintenance and supervision ensure that written procedures have been adopted to prohibit equipment on both sides of the aisle from being open at the same time and qualified persons who are authorized will service the installation.

There's nothing analogous for over 600V.

Edit Add: It would make a good Proposal

[ January 27, 2005, 04:53 PM: Message edited by: rbalex ]