A bank of electric heaters has a power rating of 25 kw. the heaters are connected to 480 volts. theheaters will operate for more than three hours at a time. the conductors supplying the heaters are tobe aluminum with type thwn-2 insulation. the heaters are located in an area with an ambient tem-perature of 48°c. there will be six conductors in the conduit. what size conductors should be used for this installation?