General purpose transformers in Class I, Div 2 locations

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Johnny Bravo

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I'm trying to determine if installing a 45kVA General-purpose low-voltage dry-type 3-ph transformer (such as the SquareD EX45T3HCU) in a Class I, Division 2 (Groups C&D) would be a code-violation. The transformer is a 480V delta primary, with a 208Y/120V secondary.

NEC 2011 501.100 (B) points to 450.21 through 450.27.
Using the 45kVA transformer that I linked, 450.21 seems to indicate that there is no restriction as long as my transformer is "completely enclosed, with or without ventilating openings". I do not read this as being a sealed encapsulated transformer, but I could be wrong. Would you say that the linked transformer does not violate the code, and therefore can be installed in a Class I, Div 2 area?

I have asked a couple of major electrical manufacturers this question and received their answer, but I don't want to overly bias the conversation before hearing your thoughts.

Thanks.
 
What 501.100(B) is telling you is that Class I, Division 2 adds no restrictions beyond those already in Article 450. If installed as would otherwise be required under "ordinary locations" the transformer you linked to is fine.
 
On the other hand, I would imagine that something other than a general purpose transformer, such as one with an automatic (or even manual switch?) tap changer for voltage correction might not be OK?

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GoldDigger said:
On the other hand, I would imagine that something other than a general purpose transformer, such as one with an automatic (or even manual switch?) tap changer for voltage correction might not be OK?

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Those items fall under Section 501.115(B). The transformer itself is fine.

EDIT ADD: In fact, Section 501.115(B)(2) has some interesting material about isolating switches with respect to transormers.
 
Thanks for the responses! I had asked 2 manufacturers and both claimed that if installing the transformer in a Class I, Div 2 environment, the transformer had to be a sealed resin-encapsulated transformer (at increased cost). The sealed transformer has a CID2 rating, but I'm not sure that's relevant. I understand that manufacturers don't want to accept the perceived potential liability of saying I can use a general purpose (non-CID2 rated) transformer in a CID2 area, but if the code does not prohibit it, then why is it a concern for them?
 
If your classification requires you to limit surface temperatures lower than that as a potential ignition source, it might be an issue, but CID2 does not, yes?

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GoldDigger said:
If your classification requires you to limit surface temperatures lower than that as a potential ignition source, it might be an issue, but CID2 does not, yes?

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The restriction certainly isn't in Section 501.100(B). If there were one, it would be in Section 500.8. Dig for it.
 
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