XFMR on Combustable surfaces

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Take a look 450.21 for Dry-Type transformers. The instructions I have seen also state to mount them on non-combustible flat surfaces.
 
450.21(A) has an exception below it that says if it's 600v or less, enclosed, with or without vents, it's ok. Am I understanding this right? I am looking at transformer like the one in the picture mounted on 1" plywood. You can see the front cover just to the right with vents in it. Would this be the exception to 450.21(A) since it is under 600V and fully enclosed with vents?
 

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Brandon Loyd said:
450.21(A) has an exception below it that says if it's 600v or less, enclosed, with or without vents, it's ok. Am I understanding this right? I am looking at transformer like the one in the picture mounted on 1" plywood. You can see the front cover just to the right with vents in it. Would this be the exception to 450.21(A) since it is under 600V and fully enclosed with vents?
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Yes, the exception to 450.21(A) would apply to the transformer in your picture.

Chris
 
Can anyone say with certainty that this is illegal? I've been called on this before so always assumed it was not legal to install your standard, 30-45 KVA, dry type, indoor, XFMR's like this one, on wood or carpet. But this exception makes it sound perfectly legal. Can anyone else argue this? If the XFMR has that little angled opening across the top of the cover, in front and back, is it still considered to be "completely enclosed"? Is it illegal because of something silly like that?
 
Brandon Loyd said:
Can anyone say with certainty that this is illegal? I've been called on this before so always assumed it was not legal to install your standard, 30-45 KVA, dry type, indoor, XFMR's like this one, on wood or carpet. But this exception makes it sound perfectly legal. Can anyone else argue this? If the XFMR has that little angled opening across the top of the cover, in front and back, is it still considered to be "completely enclosed"? Is it illegal because of something silly like that?
Click to expand...

The exception allows for ventilating opening in the transformer enclosure. The transformer in the picture is totally enclosed in accordance with the exception IMHO.

Chris
 
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