Light Bulb Base Types
Decoding Edison Bulb Base Types
The common terms are medium, intermediate, candelabra and mogul. However, because the light industry likes mysterious codes, you may also see E26, E12, E39, etc. E obviously is for Edison. The number after the E is the diameter of the base in millimeters.
Here are the most common Edison base codes.
- Medium (think household 60W bulbs) = E26
- Intermediate = E17
- Candelabra = E12
- Mini Candelabra = E11
- Miniature = E10
- Midget = E5
The large Mogul bases found on higher wattage incandescent and HID bulbs are E39.
Most Edison base bulbs are called "single contact" because there is one contact button at the center of the base. However a few are called "double contact" (two buttons) in which case the designation becomes E26d or E39d.
The good news is there are relatively few Edison base designations. It really gets crazy with pin-based bulbs - there are well over 75 different types!