Working space question: 480V VFD facing 480V Mechanical Air Handling Unit (AHU)

[fandi]

Hello All,
We have 42" clearance between the VFD and the AHU. They're front facing each other. We run out of room to relocate the VFD. Per NEC Table 110.26(A)(1), Condition 2 needs 42" whereas Condition 3 needs 48".
Is 42" sufficient in this case?
Thanks.

 

[qcroanoke]

Hello All,
We have 42" clearance between the VFD and the AHU. They're front facing each other. We run out of room to relocate the VFD. Per NEC Table 110.26(A)(1), Condition 2 needs 42" whereas Condition 3 needs 48".
Is 42" sufficient in this case?
Thanks.

No, according to what I see in the explanatory exhibit 110.12 2014 NEC.
you need 48 inches.

 

[fandi]

No, according to what I see in the explanatory exhibit 110.12 2014 NEC.
you need 48 inches.

But that same exhibit 110.12 (2011 though) shows permitted reduction from Condition 3 to Condition 2 according to 110.26(A)(1)(c) for existing buildings as long as they are not being open at the same time.

 

[qcroanoke]

But that same exhibit 110.12 (2011 though) shows permitted reduction from Condition 3 to Condition 2 according to 110.26(A)(1)(c) for existing buildings as long as they are not being open at the same time.

You are correct. I did not read far enough along in the article.
Are you replacing equipment or trying to get something in a space that didn't have anything in it before?

 

[fandi]

You are correct. I did not read far enough along in the article.
Are you replacing equipment or trying to get something in a space that didn't have anything in it before?

It's an existing building. If it was new, I would designate 48" clearance and be done with it.
Anyway, I need to have contractor put a sign with the wording as the exhibit suggests.

 

[qcroanoke]

It's an existing building. If it was new, I would designate 48" clearance and be done with it.
Anyway, I need to have contractor put a sign with the wording as the exhibit suggests.

Unless you are replacing existing equipment I don't believe you can reduce the clearances required.
110-26.1.(c) Existing buildings. In existing buildings where electrical equipment is being replaced, condition 2 working shall be permitted between dead-front switch boards,
switchgear, panel boards or motor control centers

 

[fandi]

Unless you are replacing existing equipment I don't believe you can reduce the clearances required.
110-26.1.(c) Existing buildings. In existing buildings where electrical equipment is being replaced, condition 2 working shall be permitted between dead-front switch boards,
switchgear, panel boards or motor control centers

Yes, the AHU is being replaced.

 

[qcroanoke]

Yes, the AHU is being replaced.

Then you're gold.