Siemens K36 Thermal Overload Heater Element – Class 20 | 4.36–4.99A
Siemens K36 Thermal Overload Heater Element – Class 20 | 4.36–4.99A
Product images are representative only. Actual product may vary.
The Siemens K36 is a precision thermal overload heater element designed for use with Siemens and Furnas Class 20 overload relays. Rated for a motor full-load amperage range of 4.36 to 4.99 amperes, the K36 heater element provides accurate, thermally-responsive motor protection in single-phase and three-phase applications.
Heater elements like the K36 are installed inside thermal overload relay units and serve as the trip-sensing mechanism — they heat up proportionally to motor current, causing the relay to trip when sustained overcurrent conditions are detected. The K36 is a direct OEM replacement for Siemens/Furnas motor starters across multiple NEMA sizes.
Key Specifications
- Part Number: K36
- Manufacturer: Siemens (Furnas Electric)
- Element Type: Thermal Overload Heater
- Trip Class: Class 20
- Motor FLA Range: 4.36–4.99 Amperes
- Compatible NEMA Sizes: 00, 0, 1, 1P, 1-3/4
- Application: Single-phase and three-phase motor protection
- Ambient Temperature Rating: 40°C (104°F)
- Certifications: UL Listed, CSA Certified
How to Select the Right Siemens Heater Element
Selecting the correct Siemens K-series heater element depends on three factors: motor full-load amperage (FLA), starter NEMA size, and motor service factor. Use the Siemens overload relay heater table for your specific starter class and size to confirm the K36 is the right fit:
- For motors with 1.15–1.25 service factor: use 100% of motor FLA for selection
- For motors with 1.0 service factor: use 90% of motor FLA and select the next lower heater element
- If motor and controller are in different ambient temperatures, apply the ambient temperature correction multiplier per Siemens heater selection tables
Why Choose the Siemens K36?
- OEM Accuracy: Factory-calibrated to Siemens trip specifications — ensures reliable Class 20 protection without guesswork.
- Wide Starter Compatibility: Works across NEMA Sizes 00, 0, 1, and 1P in Siemens and Furnas motor starters.
- Easy Replacement: Direct plug-in replacement — no rewiring or panel modification required.
- Cost-Effective Protection: Replacing a worn or mismatched heater element is far less costly than a motor rewind or replacement.
Typical Applications
- Siemens and Furnas NEMA motor starters (Class 10 and Class 20)
- Small pump and fan motor protection (1/2 to 2 HP range)
- Compressor and conveyor starter panels
- HVAC equipment and building automation motor starters
- Industrial process control panels
Compatibility Note
The K36 heater element is part of the Siemens K-series heater range. Always reference the official Siemens overload relay heater tables for your specific starter model, class, and enclosure type before ordering. Installing an incorrect heater element can result in nuisance tripping or inadequate motor protection.