Short circuit ratings

[ron]

Re: Short circuit ratings

Bob,
Thanks for the reference. Although I'm not sure I read it the same way. It seems that they are acknowledging that a momentary parallel operation may be permitted, they don't seem to indicate objection in the panel statement (other than the Reject) to the idea of considering only one source for evaluating the equipment and associated AIC.

Edit add: Was this the most recent code cycle, or before?
It also indicates that it is not a blanket rejection as they seem to be flexible on a case by case basis.

[ December 03, 2004, 10:39 AM: Message edited by: ron ]

 

[rbalex]

Re: Short circuit ratings

Ron,

Yes this was the latest Proposal. While the CMP statement may seem flexible, I still resist it being a 90.4 "special permission."

I talked about it a bit more here.

I almost have my next version ready for posting on the "2008 Proposals" forum.

 

[ron]

Re: Short circuit ratings

Bob, where you involved in the 1-150 Log #2969 NEC-P01 proposal from the American Petroleum Institute you printed?

 

[rbalex]

Re: Short circuit ratings

Ron,

No, I wasn't involved that time. I left the API Subcommittee on Electrical Equipment (SOEE) in March 2002. Their NEC caucus was in September that year.

I'm somewhat surprised they have continued the fight. Quite a few of the SOEE "User" members operate as if they aren't required to comply with the NEC (or OSHA) because their facilities aren't routinely inspected. On the other hand, it was still the single most qualified technical committee I've ever worked with.

I'm leaning toward a "Registered Professional Engineer" clause in my next version just for the reason you mentioned.

I don't have a copy of the drawings any longer, so I'm not quoting my self entirely accurately. About a half dozen times, I've added something like the following to the "sealed" versions of a few single-lines submitted for plan-check: "Approval of this drawing by the ____ Building Department constitutes 'Special Permission' under Section 90.4 of the ____ NEC to exceed the short-circuit rating requirements of Section 110.9 of the items identified by '***', during an automatically controlled power transfer." Other notes explained the actual vulnerability limits of the specific design. Only one jurisdiction made me submit a formal variance request. I don't seal "originals" so its up to my clients to maintain a copy of the AHJ approval.

I had mentioned doing this to two members of CMP1 a year or so earlier and it may have been reflected in the Panel Statement. I don't know, I haven't discussed it with them since.