AIC rating, short circuit available and let through current
AIC rating, short circuit available and let through current
(OP)
is the let-through current via a current limiting overcurrent protective device (such as a fuse) an acceptable gauge to what aic rating the equipment needs to have? i don't think it is and the available short circuit current must be used but i can't find this in the NEC. perhaps i just overlooked it or perhaps it is somewhere else.






RE: AIC rating, short circuit available and let through current
In fact, for the purposes of calculating available SC current, the OCPDs are ignored (considered closed or shorted).
Recognized testing labs such as UL also do not recognize taking credit for the current limiting nature of any OCPD, while determining SCC rating of an assembly.
Rafiq Bulsara
http://www.srengineersct.com
RE: AIC rating, short circuit available and let through current
David Castor
www.cvoes.com
RE: AIC rating, short circuit available and let through current
Alan
RE: AIC rating, short circuit available and let through current
the handbook, written by the same author of the code itself, seems to permit let-through current.
RE: AIC rating, short circuit available and let through current
Article 240.86(A) discusses allowing a licensed engineer to determine appropriate series rating combination in EXISTING INSTALLATIONS in lieu of using a tested combination. However, no licensed engineer in their right mind should be willing to accept this liability.
I'm not sure what you mean by "permit let-through current". If you're saying that the NEC allows use of the "Up-over-down" method of determining let-through current, I would have to disagree with you.
At the end of the day, the local AHJ will have the final say, but I feel the NEC is pretty clear on this.
Cheers,
Dave
David Castor
www.cvoes.com