working clearance.....

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chevyx92

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VA BCH, VA
Inspector says I must have 30" clearance measured from transformer to wall, width wise. Meaning from edge of xfmr to wall has to be 30". I dont see where it says that and no he didnt give reference. I say as long as I have 30" wide of working space I am good. Transformer measures 28" wide. What do you guys say? Did I miss something??????
 
You are correct, the inspector is wrong. 110.26(A)(2)

(2) Width of Working Space. The width of the working space in front of the electrical equipment shall be the width of the equipment or 762 mm (30 in.), whichever is greater. In all cases, the work space shall permit at least a 90 degree opening of equipment doors or hinged panels.
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Roger
 
I don't reserve working space for transformers. And I don't understand the second question about other equipment in the same room. If you are talking about a transformer vault, which I have seldom encountered, then there are restrictions about non-related equipment in the same room. See article 450, part C.
 
I cannot remember how many times in my career that we have taken voltage readings at live transformers after installation. I am sure this is not an uncommon type of maintenance/testing situation across the country.

With that said, clearance is important and so is following the manufacturer's installation instructions for clearances.

Form the OP's description, it sounds like the inspector may be confusing the width of working space wording.
 
Pierre C Belarge said:
I cannot remember how many times in my career that we have taken voltage readings at live transformers after installation. I am sure this is not an uncommon type of maintenance/testing situation across the country.

With that said, clearance is important and so is following the manufacturer's installation instructions for clearances.

Form the OP's description, it sounds like the inspector may be confusing the width of working space wording.
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I would think that transformer connections are IR tested all of the time which means that they must be energized for the test.
 
infinity said:
Charlie, are you saying that in your opinion transformers don't require maintenance or testing while energized?
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Yes. IMHO, all they need is the 6 inches distance from the wall that most manufacturers require, for the purpose of ventilation.
 
Which article says that other electrical equipment is allowed in the work space measuring horizontally? (Ex. panels side by side, or panel next to transformer) You need 30" or width or equipment if greater but other equipment can be in this 30" zone. Where does it says this? I can't seem to find it.
 
charlie b said:
Yes. IMHO, all they need is the 6 inches distance from the wall that most manufacturers require, for the purpose of ventilation.
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Ok so how would someone perform an IR test on an energized transformer that didn't have the Article 110 required working space in front of it? Aren't those required distances in the NEC to provide an area to perform things such as energized testing?
 
This may be a reach on the part of the inspector, but what does the transformer spec for breathing room?
If it's a typical dry-type xfmr, in a nema 1 enclosure I doubt it's thirty inches but it may well be more than 1 inch.


Doug S.
 
chevyx92 said:
I have read that. Show me where in 110.26(A)(2) that it allows other electrical equipment within this working space. Thats what I'm trying to find.
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The answer is nowhere, but there is nowhere it is prohibited either, if it were, installations as shown below would be in violation wouldn't they?

CR-EQsystems.JPG


Roger
 
roger said:
The answer is nowhere, but there is nowhere it is prohibited either, if it were, installations as shown below would be in violation wouldn't they?

Roger
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I understand that. I was just looking as to where it was in the code that it was ok. They give specific mention when it comes to working height clearances to say other electrical equipment in this space is allowed. I just didn't know there was no code saying the same when it comes to working width clearance.
 
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chevyx92 said:
Show me where in 110.26(A)(2) that it allows other electrical equipment within this working space. Thats what I'm trying to find.
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You won't find it, for it is not there. You can't have anything, not even other electrical equipment, within the working space. However, the working space begins at the front of the enclosure. If two identical panels are side by side, then neither is in the working space of the other.

By contrast, consider a 12 inch deep panel right next to a 5-3/4 inch deep, 22 inch wide panel, with another 12 inch deep panel right on the other side. Here, the panel in the middle has a working clearance that is only 22 inches wide, since the front faces of the others are more than 6 inches further from the wall than the front face of the one in the middle. That would be a violation.
 
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