Square D A5.78 Contactor Thermal Unit

Product Description

The SQUARE D A5.78 is a thermal unit designed as a replacement accessory for compatible SQUARE D contactors and motor starters. Thermal units provide overload protection by sensing heat generated by motor current draw, tripping the overload relay when temperatures exceed safe operating thresholds. Licensed electricians and industrial maintenance technicians install this component when replacing a spent or incorrectly rated thermal unit in an existing motor control assembly. At 0.04 pounds and compact in size, it fits directly into the overload relay block on the host contactor without modification.

This thermal unit is suited for motor control applications in commercial and light industrial settings where overload protection must be maintained or restored on existing SQUARE D contactor assemblies. Typical installation scenarios include replacing a thermally fatigued unit after a motor overload event or rerating the overload protection for a new motor load. It ships in a quantity of one per package.

Key Features

• Thermal unit accessory providing overload protection for compatible SQUARE D contactors
• Compact form factor sized for direct insertion into the overload relay block
• Lightweight at 0.04 pounds for easy handling during installation
• Single-unit packaging suitable for targeted replacement service calls

Compatibility

Designed as an OEM-style replacement thermal unit accessory for compatible SQUARE D contactors and motor starter overload relay assemblies.

Installation Notes

Installation should be performed by a licensed electrician in accordance with the National Electrical Code (NEC). De-energize and lock out the circuit before removing or installing the thermal unit. Confirm that the thermal unit rating matches the full-load amperage of the motor being protected before returning the equipment to service. Do not interchange thermal units between incompatible relay blocks.