Liftmaster K77-37335, E-BOX
The LiftMaster K77-37335 is a replacement electrical box, or E-box, used on select RSW Series swing gate operators. The E-box helps house and protect the operator electronics, wiring, and related control components inside the swing gate operator assembly. It is typically replaced when the original box is cracked, corroded, modified, missing knockouts, or no longer provides a secure mounting area for internal components.
Correct E-box fitment is important because the box must line up with the RSW operator frame, cover, conduit entry points, control board locations, and harness routing. A similar enclosure from another LiftMaster model may not have the same mounting pattern or internal clearance.
Compatible With
Common Compatible Models
- LiftMaster RSW12U swing gate operators
- LiftMaster RSW12UL swing gate operators
- LiftMaster RSW12VDC swing gate operators
Additional Model Families to Verify
- LiftMaster RSW Series residential/light commercial vehicular swing gate operators
Important Compatibility Notes
- Match the existing enclosure and parts diagram before ordering.
- This is the electrical box/enclosure, not a complete control board or full operator conversion kit.
- Do not assume compatibility with CSW, LA, RSL, or slide gate operators.
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster |
| Product Type | Electrical box / E-box |
| Part Number | K77-37335 |
| Application | Control/electrical enclosure replacement |
| Compatible Operator Type | RSW Series swing gate operator |
| Common Models | RSW12U, RSW12UL, RSW12VDC |
| Notes | Enclosure only; transfer or replace electronics as required by the repair |
Also Known As / Related Part Numbers
- K77-37335
- K7737335
- LM-K77-37335
- LIF-K77-37335
- K77-37335 E-Box
- K77-37335 electrical box
Technician Note
Use this part when the original component is damaged, missing, cracked, corroded, worn, or no longer holding the related operator assembly correctly. Because many LiftMaster and Elite parts look similar across generations, final fitment should be based on the model number and replacement parts diagram, not appearance alone.
Before Ordering
- Match the part number on the existing component or the operator parts diagram.
- Confirm the operator model, series, voltage or configuration where applicable.
- Compare mounting points, cover shape, harness plugs, and included hardware before installation.
- Do not substitute similar-looking LiftMaster parts unless the parts diagram confirms the match.
Professional Advisory
Installation should be performed with power disconnected and the gate secured. For high-voltage wiring, damaged enclosures, missing safety devices, or uncertain fitment, use a qualified gate technician.
Product Questions & Answers
What is the K77-37335 E-box?
It is a replacement electrical box used to house and protect wiring and control components on select LiftMaster RSW Series swing gate operators.
Which models are commonly compatible?
Common references include RSW12U, RSW12UL, and RSW12VDC operators.
Does this include the control board?
No. It should be treated as an enclosure/E-box replacement unless the current supplier listing states otherwise.
Why is the exact E-box important?
The enclosure must match the operator frame, cover, conduit openings, and board mounting layout.
Can this be used on a CSW200 operator?
No confirmed CSW200 compatibility should be assumed. Use it only where the RSW parts diagram specifies K77-37335.
