Square D b4.15 Melting Alloy Thermal Unit 2.52-2.99A

Product Description

The SQUARE D b4.15 is a melting alloy thermal unit designed for use with motor starters and overload relays in industrial and commercial electrical systems. It protects motors from sustained overcurrent conditions by using a eutectic alloy element that melts at a calibrated temperature, triggering the overload relay trip mechanism. This unit is rated for a full load current range of 2.52 to 2.99 amps and a maximum voltage of 600 VAC. It operates on a Standard Trip classification and carries a Trip Class 20 rating, making it appropriate for applications where motors require up to 20 seconds of trip time under locked-rotor conditions. Licensed electricians are the primary installers of this component.

The b4.15 thermal unit is suited for light-duty to medium-duty motor protection in residential, commercial, and light industrial environments. It is installed into compatible SQUARE D overload relay assemblies that accept melting alloy thermal elements. Typical applications include protection of single-phase or three-phase motors driving pumps, fans, compressors, and conveyor systems where the full load current falls within the 2.52 to 2.99 amp range. The 104 degrees F temperature rating reflects the unit calibration reference point for standard ambient conditions.

Key Features

• Full load current range of 2.52 to 2.99 amps for precise motor protection
• 600 VAC voltage rating suits a wide range of industrial motor control applications
• Melting alloy design provides reliable, repeatable overload trip response
• Trip Class 20 rating allows motors up to 20 seconds under locked-rotor before tripping
• Standard Trip type for conventional overload relay assemblies
• Compact profile at 1.88 inches height and 0.69 inches width for easy installation in relay housings

Compatibility

Designed as an OEM-style replacement thermal unit for SQUARE D melting alloy overload relay assemblies that accept b-series thermal elements. Verify the overload relay model accepts the b4.15 element before installation.

Installation Notes

Installation should be performed by a licensed electrician in accordance with NFPA 70 (NEC) requirements. Always de-energize and lock out the motor control panel before removing or inserting a thermal unit. Confirm the selected thermal unit current range matches the motor nameplate full load amps before installing. Do not substitute thermal units of different current ratings as improper selection will result in inadequate motor protection or nuisance tripping.