"IEC" would at best refer to a set of standards by which manufacturers agree to adhere. But that is essentially "self certification" meaning they SAY they meet the standards and will show you their own test results that corroborate that. But, in the litigious society that is North America, self-certification means essentially nothing. We rely upon "3rd party listings" from non-affiliated Nationally Recognized Testing Laboratories (NRTLs) such as UL and FM etc. NRTLs are going to be the only thing any local and national codes officially accept, although you can, at any given moment, find a local AHJ (Authority Having Jurisdiction) who can be convinced otherwise with a REALLY good argument (but I wouldn't bet on it). Remember, the AHJ is the lord and master of his/her own little word and has final authority.