lamp socket
The lamp base ensures the fastening and contacting of lamps in the lamp socket. Each lamp, whether incandescent, energy-saving, gas discharge, halogen or LED, they all have a lamp base. Depending on the design, it can be a classic threaded base, as it is mostly used in incandescent lamps, a plug-in base or pin base. Lamp bases are marked with a letter-number combination.
The threaded base
The classic threaded base is the Edison base named after Edison. For compatibility reasons, the threaded base is also used for energy-saving lamps and LED lights. This has the advantage that you can continue to use the existing lamp sockets. The threaded base has a screw-shaped thread with which the lamp is turned into the socket.
The threaded base forms the socket contact, the second contact is the foot contact at the lamp base. Threaded bases are standardized and marked with the letter "E". The digits following the letter "E" indicate the outer diameter of the threaded base in millimeters.
Threaded bases come in a wide variety of dimensions. The classic version of the incandescent lamp has the Edison base E27, candle lamps have E14. In addition, there are various base sizes between 5.5 mm (E5.5) to 40 mm (E40).
The plug-in base
The plug-in base consists of a plastic rectangular sleeve and two contact parts. It is used in compact fluorescent lamps. The plug-in base has the letter "G" as a standardized identifier, followed by further letters or digits, example: G24. The numbers indicate the distance between the two contact pins.
The pin base
The pin base is used in halogen lamps. It differs from the pin base in that it consists of two contact pins, but they can be of different shapes. Like the pin base, the pin base has the letter identification "G". The pin spacing is indicated by a one- or two- digit number. Example: G4, which means that the pin spacing is 4 mm. The pin diameter is usually between 0.65 and 0.75 mm and 0.95 and 1.05 mm. There are also contact pins with diameters from 1.5 to 1.6 mm.
The bayonet socket
With the bayonet socket, the lamp base is inserted into the lamp holder and fixed by a rotation. When fixing, the pins attached to the base snap into the recesses provided for this purpose, thus preventing the lamp from coming loose or changing its position relative to the reflector, even in the event of shocks. For this reason, lamps with bayonet bases are used in Germany primarily in automotive applications, but also as halogen or LED lamps for room lighting. Lamps with bayonet bases are marked with the letter "B".