Mx,
Astute? yes, correct? not sure. (if it is possible to be astue and wrong at the same time.) Our local inspectors are fairly astute as well, and they disagree. Although the disconnect or not disconnect issue may be moot because for whatever reason the CT alone is only rated 10,000 AIC and with disconnect is 100,000 AIC.
sounds like this run will be well in excess of say, 25 feet or so...
No limit to length outside the building. Are thinking of a tap rule? Even those are allowed at unlimited length outside the building.
Bob,
I was under the impression the reference would be in NFPA 20. The NFPA website is pretty nice. They let me "thumb" through NFPA 20 for free and I couldn't find anything.
Marc,
The CT cabinet was going to be 10' from the transformer. Then up and over the building for roughly 100' total of conductor to the controller in the pump room which would have the disconnect. This way I save on not having to supply the disconnect and my grounds would be easier in the pump room.
The other options are to run 325' around the building with USE (oversized for VD) or through the building with MI cable or concrete encased RMC. Because the building is the net result of (3) seperate additions, it is not possible to get a clear shot through (concrete block stairwells, subbasements with different elevations), and I'm not interested in investingating how I would encase an overhead conduit run, properly support & form and cover. Even if I could, there is still not a clear shot.
p.s. please sized the ct and related fire pump system with locked rotor amps
I'm aware of the requirement to size the disconnect to locked rotor current, but not the requirement to size the CT cabinet to LRC.
Thanks for the input gentlemen.
