To determine the heater pack needed for the Schneider 8536 NEMA starter, look on the bottom overload portion of the starter for the heater part number (should say something like B22 or B32 or something similar). If you cannot read the heater part number, you can follow the below formula:
1. Determine the full load current rating
2. Determine the service factor of the motor
For 1.15 to 1.25 service factor motors use 100% of motor FLC for thermal unit selection.
For 1.0 service factor motors use 90% of motor FLC for thermal unit selection.