Generator Switchboard

[infinity]

I have a 5000 amp switchboard fed from a 3000 KW generator. There is no main just two integral switches and 5 bus taps to separate fused 200 and 400 amp disconnect switches for fire alarm, fire pumps, smoke purge panels etc. What are the conductors used to bond the separate disconnect switches? My guess is that they're SSBJ's and that they're sized according to T250.102(C)(1) based on the tap conductors to each switch.

 

[don_resqcapt19]

Based on the language in 250.30(A)(2) I think that the SSBJ is sized based on the conductors between the generator and the switchboard. The words that lead me to say this are "A supply-side bonding jumper shall not be required to be larger than the derived ungrounded conductors.". That would never be an issue where the SSBJ is sized based on the conductors to the individual disconnects.

 

[infinity]

Based on the language in 250.30(A)(2) I think that the SSBJ is sized based on the conductors between the generator and the switchboard. The words that lead me to say this are "A supply-side bonding jumper shall not be required to be larger than the derived ungrounded conductors.". That would never be an issue where the SSBJ is sized based on the conductors to the individual disconnects.

I looked at that section but in my mind it seems to imply that there is only one disconnect after the generator.

250.30(A)(2) Supply-Side Bonding Jumper. If the source of a separately derived system and the first disconnecting means are located in separate enclosures, a supply-side bonding jumper shall be installed with the circuit conductors from the source enclosure to the first disconnecting means. A supply-side bonding jumper shall not be required to be larger than the derived ungrounded conductors. The supply-side bonding jumper shall be permitted to be of non-flexible metal raceway type or of the wire or bus type as follows:
(a) A supply-side bonding jumper of the wire type shall comply with 250.102(C), based on the size of the derived ungrounded conductors.
(b) A supply-side bonding jumper of the bus type shall have a cross-sectional area not smaller than a supply-side bonding jumper of the wire type as determined in 250.102(C).