I have a large HVAC unit. The unit RLA is 631, MCA is 665, and Max Fuse is 800A. Max breaker is 1000A. I figure using the 75 degree column of 310-16 the customer would probably use 2 runs of 500 MCM.
I was sent a revision stating the customer was bringing in 4 four inch conduits with 4 350 MCM wires and a 3/0 ground in each conduit. They are putting in a 1200A disconnect. It did not state what type of disconnect.
The ground makes me think it is AL or CU/AL wire. (Our prints state copper wire only.) I cannot figure out how the customer came up with the wire and disco. size. I am trying to see how far away the disco. is. Besides the fact they are bringing in 4W with ground and our unit is 3W 3PH w/grd, why would they bring in four sets of oversized wire?
I build end user equipment and I don't have alot of knowledge on the service entrance side, so I would appreciate any advice or explanations on this one.
Thanks,
Robert
