The Maximum Overall Length (MOL) is the total length of a lamp , measured from the very tip of the lamp (e.g. the top of the glass bulb) to the bottom of the lamp base or fitting.
The MOL is expressed in millimeters (mm) or inches and is an important specification when selecting lamps for different fixtures.
1. Why is MOL important?
✅ Determines whether a lamp physically fits in a fixture.
✅ Prevents installation problems → Lights that are too long can stick out or hinder the cover.
✅ Essential for closed luminaires → For example in recessed spotlights, car lighting and industrial luminaires .
✅ Often mentioned with replacement bulbs → To ensure compatibility.
📌 An MOL that is too long can prevent the lamp from fitting properly in the fixture, while an MOL that is too short can affect the light distribution.
2. How is the MOL measured?
The MOL is measured from the highest point of the bulb to the bottom of the socket . This applies to:
- Incandescent and LED lamps → Including the glass bulb and fitting.
- Fluorescent and tube lamps → Between the outermost ends of the tube.
- Halogen and HID lamps → From the top of the lamp to the end of the pins or threads.
💡 Example: An E26 LED bulb with an MOL of 100 mm means that the total height of the bulb is 100 mm , including the screw fitting.
3. Applications of MOL
| Application | Why is MOL important? |
|---|---|
| 🏠 Household lighting | Prevents lamps from being too big or too small for fixtures. |
| 🚗 Car lighting | Limited space in headlamp housings requires a precise MOL. |
| 🎭Theatre and studio lighting | Ensures that lamps fit correctly into fixtures without any protruding parts. |
| 🏢 Commercial and industrial lighting | For fluorescent tubes and HID lamps, a correct MOL is essential for replaceability. |
📌 MOL compatibility prevents problems when installing and replacing lamps.
4. Difference between MOL and LCL
| Term | Definition | Application |
|---|---|---|
| MOL (Maximum Overall Length) | Total length of the lamp, including fitting | Determines whether the lamp fits in a fixture |
| LCL (Light Center Length) | Distance from the center of the light source to the lamp base | Determines the light position in a reflector |
📌 MOL affects physical compatibility, while LCL determines optical performance.
💡 In short:
The Maximum Overall Length ( MOL ) is the total length of a lamp , measured from the top to the bottom of the socket. It's an important specification for fixture compatibility , especially in residential, industrial, and automotive lighting . A correct MOL prevents installation problems and ensures a proper fit.