NEC 708 Fire-rated Circuits

[msteiner]

Does anyone have experience with specifying fire-rated feeders/branch circuits to comply with NEC 708 (Critical Operations Power Systems)? I understand UL 2196 is the standard established to rate a cable assembly as "fire rated", but without access to this standard I'm curious about what the options are for 1-hr and 2-hr rated circuits (i.e. concrete encasement, MI cable, Type RHW, etc.).

On a related note, I'm also curious about why NEC 708 calls for 1-hr rated feeders for electrical equipment in the COPS area, but feeders to HVAC equipment in the same area have to be 2-hr rated.

 

[jsteed]

I think the cable we ended up specifying was from Tyco. The cable literature lists the assembly number that the cable was listed with. UL has information on the cable assemblies online. Nothing too outrageous- if I remember correctly, in our case, the cable has to be run in RGS and it may have needed a few more supports than NEC required. We used this mainly in existing buildings. In new buildings we've been able to keep the feeders either outside the building or in concrete for the most part.

We never found much information on the other two methods listed in 708- listed electrical circuit protective system and cable listed to maintain circuit integrity.

jim