Liftmaster 25-4004-K Overload, 3.7-5.5A
The LiftMaster 25-4004-K overload relay is a protective electrical component used in compatible commercial operator starter assemblies. Its job is to interrupt the motor circuit when current draw exceeds the selected range long enough to indicate a possible overload condition. In a working operator, the overload should be set according to the motor full-load amp rating and the operator wiring instructions. Replacing this part may be necessary when the overload is physically damaged, will not reset, has burned contacts, or no longer responds correctly after the motor and mechanical load have been checked. This 3.7-5.5A version should not be confused with nearby LiftMaster overload ranges such as 1.8-2.6A, 2.6-3.7A, 5.5-8A, or 8-11.5A.
Compatible With
Select LiftMaster commercial door operators and starter assemblies where the parts diagram lists 25-4004-K; commonly associated with 3-phase starter operator applications and certain SJ1023 Speed Jack references. Match the current range, contactor/starter, phase, and wiring diagram before installation.
Features and Specifications
| Manufacturer | LiftMaster / Chamberlain Group |
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| Product Type | Thermal overload relay |
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| Part Number | 25-4004-K |
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| Current Range | 3.7-5.5A |
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| Application | Motor overload protection in select commercial operator starter circuits |
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| Phase | Commonly used in 3-phase starter applications where specified |
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| Compatible Operator Type | LiftMaster commercial door operators where the parts diagram calls for this overload |
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| Notes | Match motor full-load amps and overload range before replacement. |
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Also Known As / Related Part Numbers
- 25-4004-K
- K25-4004-K
- 254004K
- 25-4004K
- LiftMaster overload 3.7-5.5A
- LiftMaster thermal overload relay 3.7-5.5 amp
Technician Note
For LiftMaster commercial operator service parts, the safest fitment method is to match the original component label and the model-specific parts diagram. Similar-looking electrical parts can have different ratings, wiring, or software versions.
Before Ordering Checklist
- Confirm the exact operator model and serial information when available.
- Match the original part number or service part number on the failed component.
- Verify voltage, phase, amp range, timing function, or control-circuit requirement before ordering.
- Compare connector layout, mounting style, terminal markings, and wiring diagram.
- Do not bypass safety devices, fire-door controls, or required monitored protection during troubleshooting.
Professional Advisory
This item may be part of a high-voltage commercial door or gate operator system. Electrical testing, motor replacement, transformer replacement, control-board service, overload adjustment, and fire-door operator repairs should be handled by a qualified technician. Never bypass required safety devices or fire-door controls to force an operator to run.
Questions and Answers
What does the 25-4004-K overload relay protect?
It helps protect the motor circuit in compatible commercial operators from sustained overcurrent conditions.
Can this replace a 25-4002-5K overload?
No. The 25-4002-5K uses a different current range. The overload must match the motor full-load amp rating and parts diagram.
Why does an overload keep tripping?
Common causes include mechanical binding, incorrect voltage, failing motor, incorrect adjustment, worn brake, or an electrical fault.
Is this used on every LiftMaster commercial operator?
No. It is used only on operators whose starter assembly and parts diagram call for the 3.7-5.5A overload.
Should the overload be adjusted after installation?
Yes. It should be set according to the motor nameplate and operator instructions by a qualified technician.
