Square D A11.9 Contactor Thermal Unit

Product Description

The SQUARE D A11.9 is a replacement thermal unit designed for use with compatible contactors and motor starters. Thermal units provide overcurrent protection by sensing heat generated during motor operation and tripping the overload relay when current exceeds safe levels. This type of component is a standard service part used by licensed electricians and HVAC technicians when restoring overload relay function after a fault condition or routine maintenance. The A11.9 ships as a single unit and installs directly into the overload relay block of a compatible contactor assembly.

Thermal units are commonly installed in residential and light commercial electrical panels, motor control centers, and HVAC equipment enclosures where three-phase or single-phase motor starters are in service. This unit is suited for replacement applications where the existing thermal element has been damaged by sustained overcurrent or requires recalibration to match a new motor load. Contractors and service technicians typically stock thermal units by class to match the full-load amperage ratings of the motors they service.

Key Features

• Contactor accessory thermal unit for overload relay replacement service
• Compact form factor at 2.5 inches length, 1.2 inches width, and 0.8 inches height
• Single-unit packaging suitable for individual replacement without bulk commitment
• Lightweight at 0.03 pounds for easy handling during panel or enclosure service

Compatibility

Designed as an OEM-style replacement thermal unit for compatible SQUARE D contactor and motor starter overload relay assemblies. Verify thermal unit class and amperage range against the motor full-load amperage and existing overload relay block before installation.

Installation Notes

Installation should be performed by a licensed electrician in accordance with NEC guidelines. De-energize and lockout/tagout the circuit before opening any enclosure or handling the overload relay assembly. Snap or slide the thermal unit into the overload relay block as directed by the contactor manufacturer documentation. Verify correct amperage class selection before restoring power to avoid nuisance tripping or insufficient motor protection.