Temperature Rating on Class, Division Rated Equipment


New member
Houston, TX, USA
First time posting here. I've been told that the temperature rating on Class, Division rated equipment only needs to be marked if the maximum surface temperature of the equipment exceeds 100ºC. Is this accurate? If so, then where can I find this rule. Is it in NEC 500?

If there is no t-rating shown on a UL listing or FM Cert or CSA Cert, then is it okay to assume the t-rating of the product is T5 or better?



Staff member
The "basic" marking rules are in Section 500.8 with some temperature specific rules in Subsections 500.8 (C)&(D). [See especially Subsections 500.8 (C)(4), (5) and (6).]

There is no general "T-Code" exclusion for 100C or below but some suitable ordinary location equipment (general purpose) may not need specific marking. [See Subsection 500.8(C)(6)]
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