When determining correct overload heater size for a motor starter, which factor is most crucial?

When selecting the correct overload heater size for a motor starter, motor amperage is the most crucial factor. This is because the overload heaters are designed to protect the motor from overheating due to excessive current. The size of the overload heater must correspond to the full load current of the motor based on its amperage rating.

Motor amperage reflects the amount of electrical current the motor draws at its rated load. If the overload heater is too small, it may trip prematurely during normal operation, causing unnecessary downtime. Conversely, if it is too large, it may not trip when the motor experiences an overload, potentially leading to motor damage from overheating.

While factors like wire gauge, motor voltage, and starter brand are relevant to the overall motor installation and operation, they do not play as direct a role in sizing the overload protection. Wire gauge affects the capacity of the circuit but is not instrumental in determining the specific protection needs for the motor. Motor voltage is important for compatibility and operation but does not influence the current that the motor draws directly. Starter brand is relevant for compatibility of components but does not define the overload requirements for the motor. Thus, focusing on the motor amperage ensures effective overload protection that aligns with the motor's operational requirements.