What is the minimum rating for safety disconnects serving hermetic refrigeration equipment?

The minimum rating for safety disconnects serving hermetic refrigeration equipment is specified to be 125% of the load current. This requirement ensures that the disconnect can handle starting currents, which are generally higher than running currents for hermetic refrigeration equipment.

Hermetic systems, such as those found in refrigeration and air conditioning, typically experience inrush currents that can exceed the normal operating current when the system starts up. By specifying a disconnect rated at 125% of the load current, it provides a buffer to accommodate these starting surges without tripping the disconnect, ensuring safe and reliable operation of the equipment.

The 125% rule is derived from the National Electrical Code (NEC) guidelines, which aim to prevent nuisance tripping and ensure that the disconnect is adequately sized to handle both the electrical load and the transient conditions during the equipment's operation. This rating contributes to both the safety of the electrical system and the longevity of the hermetic refrigeration equipment.