Equipment Short Circuit Rating

[Machiavelli999]

Article 670.3 has requirements for a permanent nameplate for machinery. This includes a short circuit current rating. This has been a requirement only since the NEC 2005 code cycle. What can be done about old equipment that is being reinstalled in a new location that does not have this rating on the nameplate?

I am asking since we had an inspector call us out on this. This is a fairly large piece of equipment with a Power Distribution Cabinet that takes a 300A, 208V, 3PH feed. So it is understandable that the inspector is asking for the SCCR. But the vendor does not have this information. I see only two ways forward. Hire a 3rd party electrical testing/certification firm that can make the determination of the SCCR. Or see if the inspector would accept installing a fused disconnect ahead of the tool equipped with a fast acting fuse. Any other options that I am missing?

 

[charlie b]

Inserting a fast-acting fuse (AKA "current-limiting fuse") is not automatically a viable option. Your power distribution center is very likely to have fuses or circuit breakers of its own. These could interact with the new upstream fuse in such a way as to prevent it from opening as quickly as is needed to prevent exceeding its design current-limiting current value. My opinion is that the inspector is improperly dismissing the "grandfather rule," in that moving a piece of equipment is not the same as redesigning the system or altering the existing installation.