Given that the 2nd edition is more onerous, what is the likelihood of an agency such as UL allowing a 3rd edition relaxation in their 2nd edition certification?
It’s an oversimplification to state that Ed 2 is more onerous than Ed 3. A better way to view it is that Ed 3 has incorporated some refinements into it that better consider some of the proven constructions from the legacy standards that were not fully considered during the original hazard-based development of 62368-1 by IEC TC108. Side openings are one example. Having said that, since 62368-1 is IEC-based and is prominently used in the IECEE CB Scheme, it would not be appropriate to a frame allowance of Ed 3 provisions under Ed 2 in the context of a decision made by a single certifier, such as UL, since decisions made by UL for a single manufacturer also would have to be carried over for other manufacturers and introduced into the IECEE CB Scheme, thus other participating NCBs would be involved. It is for this reason that dialogue is anticipated in IEC TC108 and IECEE on this topic in the coming months, but nothing has been resolved yet, so it would be premature to provide a definitive opinion on the likelihood.