Question

The steam radiators in an old school building have given out in three adjacent classrooms. The steam piping itself seems to be working for now. It has been decided to do an extensive remodel of the school during next summer. But for now, with winter coming, it has been decided to install three electric baseboard heaters in each of three classrooms as a temporary fix (9 heaters total). The best way to run the raceway to feed all of these baseboard heaters is in the same space as the existing steam piping. Even though the steam piping is insulated, the ambient temperature in that space has been determined to be 125F. Each baseboard heater is rated at 1,500 Watts at 120v. We will use XHHW insulation due to the heat and potential moisture. The raceway running to the first classroom must contain the circuits for all three classrooms. Each heater should be on its own circuit. What size conductors will be used?