Overview
The Square D B1.03 overload relay thermal unit is a replacement heating element designed for use in Square D magnetic starters and overload protection devices. This lot includes six new, factory-condition thermal units. The B1.03 provides reliable motor overload protection using a bimetallic sensing method and standard trip characteristics.
Key Features
- Plug-in mounting design for easy installation and replacement
- Class 20 standard trip classification for typical industrial motor applications
- Melting alloy sensing technology for consistent thermal response
- Single unit rated 0.74–0.81 A full load amperage protection
- 6-pack quantity—ready to stock your maintenance inventory
- New in box condition, tested and ready to install
Technical Specifications
- Manufacturer: Square D (Schneider Electric)
- Model: B1.03
- Trip Class: Class 20, Standard Trip
- Mounting: Plug-in
- Motor FLA (Single Unit): 0.74–0.81 A
- Motor FLA (3-Unit Combination): 0.7–0.77 A
- Sensing Method: Melting Alloy
- Package Quantity: 6 units per lot
- Condition: New in Box
- Trip Current Rating: 1.25× minimum full load current (standard)
Typical Applications
Thermal units are essential replacement components for:
- Square D magnetic motor starters (NEMA, definite purpose)
- Three-phase motor overload protection in industrial control systems
- Emergency repair and maintenance of starter assemblies
- OEM equipment manufacturing and integration
- Preventive maintenance programs for aging equipment
Compatibility & Replacements
Compatible With
- Square D B-series magnetic starters
- Square D Class 8536, 8540, 8630, and 8640 starters
- NEMA and definite purpose starter enclosures accepting B-type thermal units
- Square D overload relay assemblies rated for Class 20 thermal elements
Replaces / Drop-In Replacement For
Verify compatibility with your system integrator before ordering. The B1.03 is a direct thermal unit replacement for Square D starters originally equipped with B1.03 heating elements. Always confirm the original thermal unit model number before installation.
Works With
- Square D motor protection software and coordination tables
- Standard motor overload protection circuits (Class 20 thermal response curves)
- Motor nameplate full load current selection and sizing tables
- Ambient temperature-compensated or standard-response designs (verify ambient conditions)
