Square D A.86 Contactor Thermal Unit

Product Description

The SQUARE D A.86 is a thermal unit designed for use with compatible Square D contactor and overload relay assemblies. Thermal units serve as the current-sensing element inside an overload relay, melting or deflecting under sustained overcurrent conditions to trip the relay and protect the connected motor or load. Selecting the correct thermal unit for the application current range is critical to proper motor protection. This unit ships as a single piece and weighs approximately 0.04 pounds, with a compact footprint of 2.4 inches in length, 1.2 inches in width, and 0.8 inches in height.

Thermal units like the A.86 are found in commercial and industrial electrical panels, motor control centers, and HVAC equipment control circuits where overload relays protect compressor motors, fan motors, and pump motors. Electricians and HVAC controls technicians install them during new motor control installations or when replacing a tripped or failed thermal unit as part of routine overload relay service.

Key Features

• Functions as the current-sensing element inside a compatible Square D overload relay
• Compact size: 2.4 inches long, 1.2 inches wide, 0.8 inches tall
• Lightweight at 0.04 pounds for easy handling during installation
• Single-piece package quantity for direct one-for-one replacement
• Classified as a contactor accessory thermal unit per manufacturer specifications

Compatibility

Designed as an OEM-style replacement thermal unit for compatible Square D overload relay assemblies. Verify the required thermal unit designation against the overload relay nameplate and motor full-load amperage before ordering, as thermal units are current-range specific.

Installation Notes

Thermal units are installed by licensed electricians or qualified HVAC controls technicians. Always de-energize the motor control circuit and verify zero voltage with a meter before opening the overload relay enclosure. The correct thermal unit must be selected based on the motor full-load amp rating per the overload relay manufacturer selection chart — installing an incorrect unit will result in improper motor protection. Work performed on motor control circuits must comply with applicable NEC requirements and local electrical codes.