110.26(C)(1) Large Equipment Working Space

[steve66]

I have an existing 4000KVA substation with the primary at 13.2 KV. It is currently in a large open room. The back of it is about 2' from the wall behind it. There is about 14' clear in front of it, and both sides are clear. The owner wants to put a new wall about 5' from one side of the substation (new wall will go from the wall behind the unit to the wall about 14'in front of the unit).

The new wall will eliminate the entrance to one end of the equipment. Can I use 110.26C exception (a) or (b) even though there is 2' behind the unit?

Steve

 

[charlie b]

Re: 110.26(C)(1) Large Equipment Working Space

I think you mean conditions (a) and (b) under 110.33(A)(1), since you are using 13.2 kV equipment.

My answer is ?yes? and ?yes,? in that order. You need a clear path to the single exit to meet condition (a). Only you can tell us whether or not that applies. You do have double the working clearance that condition (b) would require. From Table 110.34(A), double 5 feet equals 10 feet, and you have 14 feet.

 

[steve66]

Re: 110.26(C)(1) Large Equipment Working Space

My mistake Charlie B, you cited the correct code reference.

To rephrase this a little simpler, I do have an unobstructed path from the front of the equipment to an exit. But if someone were behind the substation, they would have to go around either side of the equipment to get out. That's what I'm concerned about.

Steve

 

[charlie b]

Re: 110.26(C)(1) Large Equipment Working Space

Interesting question. I presume that no one would be working on electrical equipment while standing in that 2 foot area. If this were not true, you have a serious problem now, even before the wall is built.

The NEC rule has only to do with a person working on the electrical equipment while it is energized. The intent is to give that person an opportunity to leave the room. There is no requirement that any person located anywhere in the room must have an unobstructed pathway out. The only person needing that pathway is the person working on the electrical equipment.

By the way, which way do the doors/access panels of the equipment open? If they are hinged in such a way that when they are open, the open door/access panel is between the worker and the exit, then you do not have an unobstructed path. The door/access panel becomes an obstruction. If they must be completely removed in order to gain access, there is no issue.

 

[steve66]

Re: 110.26(C)(1) Large Equipment Working Space

Thanks Charlie, that clears up a lot.

For the unobstructed path exception, I would have a door installed directly in front of the equipment (on the wall 14' in front of the equipment). So someone would exit by moving straight away from the equipment.

It would be a similar layout for the double working space exception, except the door would on a side wall. A worker would exit by moving straight away from the equipment until they are out of the working space, then move to the side to exit.

One more question (I hope I'm not trying your patience):

What if the emergency egress door from the equipment room leads out onto a roof? There are permanent ladders to get to the ground, but anyone who can't operate a door handle (thus the panic bars) probably can't climb down a ladder.

 

[charlie b]

Re: 110.26(C)(1) Large Equipment Working Space

Originally posted by steve66: It would be a similar layout for the double working space exception, except the door would on a side wall. A worker would exit by moving straight away from the equipment until they are out of the working space, then move to the side to exit.

I don?t think that would satisfy the rule. As I read the rule, at the moment I am about to start working on the equipment by reaching my hands within the cabinet, I must be able to turn my head and see the exit door. If I have to change directions on my way out, by virtue of any obstruction, including the cabinet door, being in my way, it is a violation.

Originally posted by steve66: What if the emergency egress door from the equipment room leads out onto a roof?

I don?t think that matters. The rule does not require a path to the parking lot. It only requires a path out of the room. I have seen it argued that a door that leads to another room that has no other exit would also count (i.e., as the second manner of egress). The idea is to get to a place of safety (i.e., away from the energized equipment), at least until a rescue can be made (e.g., until the equipment is turned off, and the room becomes safe to enter).

 

[steve66]

Re: 110.26(C)(1) Large Equipment Working Space

That was my thinking about the rooftop also. Its nice to know someone else agree's.

I think we are in agreement on everything else also. But, I don't think I made it clear that if the worker has to change directions to get out, I would be using the "extra working space" exception instead of the "unobstructed exit". Nothing under the "extra working space" exception requires an unobstructed exit.

Thanks for all the help:

Steve