Lamp Base Sizes

The bulbs have right hand threaded metal bases caps which screw into matching threaded sockets lamp holders.

Lamp base sizes. Light bulbs for automobiles are made in several standardized series. All lamps have a specific bulb type designation that describes the shape of the lamp and the size of the lamp diameter. Light bulb socket sizes chart. They are commonly used for general lighting in standard light fixtures such as ceiling lights lamps can lights outdoor spotlight and flood light fixtures and vanity lights.

It was developed by thomas edison patented in 1890 and was licensed in 1909 under general electric s mazda trademark. The letter indicates the shape of the lamp and the number relates to the diameter of the lamp in eighths of an inch. Bulbs with these bases are the most popular of all screw base bulbs. You can compare most common e size designations with a thread diameter see the specific light bulb name for that size see what are the most common applications and even see the official standard for light bulbs.

Here is the light bulb socket size chart to help you determine what size do you need your light bulb to be. Bulbs used for headlamps turn signals and brake lamps may be required to comply with international and national regulations governing the types of lamps used other automotive lighting applications such as auxiliary lamps or interior lighting may not be regulated but common types are used by many automotive manufacturers. For bulbs powered by ac current the thread is generally connected to neutral and the. Bulbs with these base types can be used interchangeably as there is only a 1 millimeter difference in base size.

The designation is a two part code consisting of a letter and a number.