Product Overview
Allen-Bradley N18 Type N Heater for Motor Overload Relays
Thermal overload heater elements are calibrated components used in Allen-Bradley overload relays and motor starters to protect motors from sustained overcurrent. By converting line current into heat, the heater mirrors motor thermal behavior and provides inverse-time protection rather than instant interruption. Correct selection is based on motor nameplate current and relay design, not horsepower alone, across single-phase / three-phase AC motor systems.
Product Condition
Unused, New Old Stock.
Product Overview
The Allen-Bradley N18 is a Type N thermal overload heater element from the legacy N-Series. It installs into compatible Allen-Bradley overload relays and magnetic motor starters that accept screw-in Type N heaters. During sustained overloads, the heater warms the relay’s internal bimetal or eutectic mechanism until the calibrated trip point is reached.
Key Features
- Allen-Bradley Type N thermal overload heater element
- Designed for compatible Allen-Bradley overload relays and motor starters
- Provides inverse-time motor overload protection, typically Class 20
- Heater selection value corresponds to approximately 2.88 A motor full-load current
- Each N-number is electrically calibrated and not interchangeable
- Similar physical form factor across Type N heaters with different trip characteristics
- Part of the legacy N-Series used in NEMA motor control equipment
Applications
- Motor overload protection in magnetic motor starters
- General-purpose AC motor control circuits
- Small three-phase induction motor installations
- Single-phase motors near 3 A full-load current
- Maintenance and repair of legacy Allen-Bradley starters
- Industrial control panel refurbishment
Frequently Asked Questions
What does the N18 heater number indicate?
The N18 designation identifies a specific thermal calibration tied to a narrow motor full-load amp range. Selection is made using Rockwell Automation heater tables based on motor nameplate FLA and application conditions.
Are Type N heaters interchangeable if they fit the same relay?
No. Although Type N heaters share a common mounting style, each N-number has a different electrical calibration. Substituting sizes can cause nuisance tripping or inadequate motor protection.
How does N18 compare to other N-Series heaters?
N18 is intended for higher full-load current motors than N16 and will trip at a higher sustained current in the same overload relay frame.
What equipment is this heater designed to work with?
The N18 is designed for Allen-Bradley overload relays and magnetic motor starters that accept Type N heater elements, commonly found in legacy NEMA motor control assemblies.
You can reestablish proper inverse-time motor protection in a legacy magnetic starter by installing this N18 Type N heater element into the existing overload relay block matched to the motor’s nameplate full-load current.
