The bi pin lamp base or socket is one of the most common types of sockets used in fluorescent lights and many types of halogen lights. The term bi pin designates the socket is designed to accept a bulb that has two pins that insert into the socket to make the connection to the power supply and to hold the bulb in place.
There are different configurations and options possible with a medium bi pin socket. This includes both the shape of the pins and their distance apart. While this can make it more challenging in buying replacement sockets or when trying to match bulbs for a socket, it also has a significant benefit.
By having specific and different configurations, the bi pin socket only accepts a bulb that is rated for the fixture. This prevents the accidental replacement of a high power bulb on a low power ballast or fixture, which increases the risk of electrical problems. By preventing high power bulbs in some fixtures, safety issues with heat buildup or even electrical fires can be prevented.
Mini Bi pins, Straight Pins, and Twist Lock Configurations
The mini bi pin is used for smaller bulbs with a short distance between pins. These pins are typically straight and very easy to change out as needed. Straight pins for larger sockets have a greater distance between the pins, and they also have thicker pins.
Twist lock configurations on a bi pin socket have a foot or an expanded area at the end of the pin. These are inserted into the socket and rotated to lock the bulb into the socket. This type of configuration is common with compact fluorescent lighting as well as LED and halogen lamps.