LiftMaster K25-4018-D Overload, 12-18A
The LiftMaster K25-4018-D is a motor overload protection component for select commercial and industrial door operator starter assemblies. Its function is to monitor the motor load and trip when current rises outside the allowable range for the motor and operator configuration. This helps reduce the chance of motor overheating when the door is overloaded, mechanically bound, incorrectly balanced, or when the motor circuit has a fault.
This part is amperage-specific. The 12-18A range makes it different from lower-range overloads used on other voltages, horsepower ratings, or phases. A correct match depends on the operator model, electrical box diagram, line voltage, phase, horsepower, and the motor nameplate full-load amp rating. If the overload trips repeatedly, the door system and motor circuit need to be diagnosed rather than simply replacing the overload.
Compatible With
This part should be matched by the operator model, electrical box, voltage/phase, motor label, and the LiftMaster parts diagram. Compatibility below is based on commonly referenced LiftMaster/Chamberlain commercial door operator parts information and should be verified against the unit being serviced.
- LiftMaster GH 5HP commercial door operators where the diagram calls for K25-4018-D or 25-4018-D
- LiftMaster GH5HP23M electrical box / motor starter references that list the 12-18 amp overload
- Select LiftMaster commercial operator starter assemblies using a 12-18A overload range
- High-horsepower commercial door operator applications where the existing overload part number and amp range match
- Not interchangeable with 25-4010-D, 25-4008-D, 25-4013-D, 25-4025-D, or other overload ranges unless confirmed by diagram and motor data
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster |
| Product Type | Thermal overload / motor overload relay |
| Part Number | K25-4018-D |
| Amperage Range | 12-18A |
| Application | Motor starter overload protection |
| Compatible Operator Type | Select LiftMaster GH 5HP commercial door operators |
| Common Model Reference | GH5HP23M where listed by parts diagram |
| Notes | Match overload range to motor nameplate and operator wiring diagram |
Also Known As / Related Part Numbers
The following numbers and search variations are commonly associated with this listing or nearby service parts. Related numbers are not automatic substitutes unless the parts diagram, voltage, amperage, or function matches.
- K25-4018-D
- 25-4018-D
- LIF-K25-4018-D
- 06 25-4018-D
- 12-18 Amp overload
- 12-18A overload relay
- GH5HP23M overload
- GH 5HP overload
- Related but different: 25-4010-D 7-10A overload
- Related but different: 25-4008-D 5.5-8A overload
- Related but different: K25-4013-D 9-13A overload
- Related but different: K25-4025-D 16-24A overload
Technician Note
Do not replace an overload with a higher amp range to stop nuisance tripping. Repeated tripping can indicate an overloaded door, mechanical drag, brake issue, low voltage, failing motor, incorrect phase, or starter problem.
Before Ordering
- Confirm the exact overload number on the existing part or GH 5HP diagram
- Match the amp range to the motor nameplate full-load amps
- Verify operator voltage, phase, and horsepower before ordering
- Inspect the door balance, gear reducer, brake, and motor if the overload has been tripping
- Use a qualified technician for motor-control diagnosis and adjustments
Professional Advisory
This part is part of a line-voltage motor starter circuit. Incorrect sizing or wiring can damage the motor or create an unsafe operator condition. Follow the operator wiring diagram and have a trained commercial door technician perform electrical service.
Questions & Answers
What does the K25-4018-D overload do?
It helps protect the motor circuit by tripping when current draw exceeds the selected overload range for the motor and operator configuration.
Is K25-4018-D the same as 25-4018-D?
Yes, K25-4018-D and 25-4018-D are commonly used for the same 12-18A LiftMaster overload reference.
Can this replace a 7-10A overload?
No. A 12-18A overload should not be used in place of a 7-10A overload unless the LiftMaster parts diagram and motor nameplate specifically require it.
Why does the overload keep tripping?
Common causes include a heavy or binding door, incorrect spring balance, motor problems, low voltage, phase issues, brake drag, or incorrect overload setting.
Is this overload only for GH 5HP operators?
The strongest common reference is LiftMaster GH 5HP, especially GH5HP23M. Use it on other operators only when the exact parts diagram calls for this part.
