A panelboard for a commercial building is supplied by 250 ft, four-wire, 480Y/277 V, three-phase feeder. The panel has the following loads:

• A lighting system of a total power 30 kVA with a power factor of 0.93

• A 15 kVA resistive heater with a power factor of 1.0

• A motor rated at 8 kVA and a power factor of 0.82 Determine

(a) The size of the feeder and conduit using THW copper conductors (use only the ampacity criterion and the appropriate demand loads).

(b) The voltage drop in the feeder (assume a steel conduit).

(c) The size of the feeder and conduit if a limit for the voltage drop is set to be 1% and the feeder should be able to handle a symmetrical short-circuit current is 35,000 A. A circuit breaker is used to protect the feeder.