Overview
The Square D B12.8 thermal overload heater element is a type B thermal sensing unit designed for motor overload protection in industrial motor control systems. This lot includes three units, each providing reliable protection across NEMA sizes 00–7. Built with proven melting alloy technology, the B12.8 delivers consistent Class 20 standard-trip performance for magnetic motor starters, separately mounted overload relays, and AC/DC motor control equipment.
Key Features
- Melting alloy sensing element for accurate thermal detection and response
- Class 20 standard trip classification for consistent motor protection
- Plug-on mounting for quick installation and field replacement
- Type B / Type S series configuration compatible with Square D overload relays
- Rated for 8.48–9.83 amps full-load motor current
- Maximum voltage rating 600V AC/DC
Technical Specifications
- Amperage Rating: 8.48–9.83 A (full-load motor current)
- Maximum Voltage: 600 V AC/DC
- Trip Class: Class 20, Standard Trip
- Sensing Technology: Melting Alloy
- Mounting Type: Plug-On
- Series/Type: Type B / Type S
- NEMA Compatibility: Sizes 00–7
- Package Quantity: 3 units
Typical Applications
- Three-phase induction motor protection (8.5–10 HP range)
- AC magnetic motor starters and contactor-based systems
- Separately mounted thermal overload relay installations
- Industrial process equipment and machinery requiring standard overload response
- HVAC, pump, fan, and conveyor motor control circuits
Compatibility & Replacements
Compatible With
- Square D thermal overload relays (B and S series frames)
- Square D magnetic motor starters and contactor assemblies
- Square D Class 2110 and similar overload relay designs
- Industrial AC/DC motor control equipment rated 600 V
- NEMA 00 through 7 motor starter enclosures
Replaces / Drop-In Replacement For
- Verify compatibility with your system integrator or equipment documentation before ordering. The B12.8 is a standard Square D type B thermal unit and matches applications requiring 8.48–9.83 A protection in Class 20 service.
Works With
- Square D overload relay assemblies with B-series thermal sockets
- Thermal overload protection circuits for three-phase motors
- Manual and magnetic motor starters using plug-on thermal elements
- Standard industrial control systems operating 50/60 Hz AC
