Medical clinic X Ray Unit

[Riograndeelectric]

I am wirng up a new X ray for a small medical clinic . they are replacing the old one with a new one. My question is looking at the 2008 code It says the rating of the feeders and and disconnecting shall be sized at 50% of the momentary rating of the Generator.

The unit is a 32KW single Phase 208 volt Generator momentary current is 220amps. and manufacture specs out 120 amp over current and disconnecting means with # 4 copper wire from disconnect to Generator.
#4 copper does not correspond to 120 amp rating. I will need to install a 125 amp breaker to feed the disconnect and I come up with #2 Copper. is #4 wire legal to use in that the manufacture specs # 4 and this is how it is UL listed. the Xray unit is made in Canada any help would be appreciated on this.

 

[chris kennedy]

Looks like your confusing 660.6(A) and (B). Feeders should be not less than 100% momentary.

 

[Riograndeelectric]

660.6(A) 2008 nec. 50 %of momentary and 100 % of long -time rating.

(B) Feeders: nFeeder for 2 or more branch circuits shal be not less than 100%of momentary.

 

[chris kennedy]

The unit is a 32KW single Phase 208 volt Generator momentary current is 220amps. and manufacture specs out 120 amp over current and disconnecting means with # 4 copper wire from disconnect to Generator.

Then that is fine.

#4 copper does not correspond to 120 amp rating. I will need to install a 125 amp breaker to feed the disconnect and I come up with #2 Copper. is #4 wire legal to use in that the manufacture specs # 4 and this is how it is UL listed. the Xray unit is made in Canada any help would be appreciated on this.

I see what your getting at. The manufacturer did not spec a feeder size so thats you. IMO the feeder must comply with 215 and 220.

 

[Riograndeelectric]

what I do not understand is if my feeders require a#2 copper wire and then from the disconnect to Generator the manufacture specs out #4 copper with 120amp fuses how does this meet Code? I understand that the manufacturer is the one specifying the #4 wire and that they can do this since they have the UL listing under this spec but it still does not make sense.

the FPN in th handbook in 517 says the manufactures will list the wiring guidelines however the FPN does not qualify as part of the code?