dashburn
Member
- Location
- Crofton, MD
We have been contracted with a GC on a design-build project to replace an existing 480Y277V generator. The GC has a contract with an engineering firm for the design. The existing generator feeds a 1200 amp emergency panel and a 50HP fire pump transfer switch/controller. The panel is fed with 4 sets 4/500MCM & 1-3/0 ground and the fire pump controller has a separate feeder using a 2-hour rated 1/0 MC cable. The new 750KW generator comes with a united mounted 1200A breaker. The engineer wants to design a system according to article 240.21; A new wire-trough accepting 4 sets of 4#350MCM installed downstream from the unit mounted 1200A device. Two over-current protective devices, each sized per code, one for the fire pump and the other for panel EMDP will be installed at the wire trough with new feeders sized accordingly for each load that can be connected to the existing feeders. We disagree with the design. Article 695.4(A) allows the direct connection of the fire pump controller feeder. Article 695.4(B) permits, but does not require, a disconnecting means and associated overcurrent protection for a fire pump controller feeder. Article 695.3(D)(2) allows the connection on the load side of the generator disconnecting means. We believe our method prevents the inadvertent disconnection of the fire pump feeder. What is your opinion?
