Is very common to get confused about which type of socket you need for each light, there are sockets with different shapes, sizes and materials so it’s very confusing. Usual sockets are catalogued into four types: Screw, pins, wedges and bayonets. Let’s see what are the differences between these types of sockets.

Screw Sockets

The most common and easy to identify socket is called Edison Screw Socket.

Edison Screw Sockets have an indication code; the code starts with an “E” (Edison) and it continues with a number representing the diameter of the bulb in millimetres. Let’s see an example, the E27 socket is for E27-Light bulb, choosing the correct light for Edison sockets is an easy task.There are different types of Edison Screw Sockets, depending on the material, there are plastic made, porcelain or metal. With plastic and porcelain sockets are usually on black or white colours, meanwhile metal sockets have different colours like bronze, nickel or brass, depending on the manufacturer. The material doesn’t matter, it is only an aesthetic choice.

Pin Sockets

These types of sockets are made for linear tubes, plug-in CFL lamps, HID lamps, MR16s and LED versions of each type of light. Pin bulbs are based on sticking pins to connect to the electrical current by the socket, usually pin bulbs have between 1 and 4 pins. The identification of this socket is made by a letter “G” and following a number that represents the distances between the pins in millimetres. Linear tubes and LED tubes are pushed into the socket and rotated to the correct position.
For example the G9 socket is designed for G9 lights.

Wedge Sockets

Wedge sockets and bases differ greatly from more conventional sockets and bases because they do not have a metal cap and pins. Instead, to seal it, the bulb's glass tapers to a point. Two wires that serve as contact points protrude from the base's bottom.

Bayonet Sockets

Although uncommon, bayonet sockets are named after the bayonets used on rifles because they have similar connection methods. 

In order to lock into place, bayonet socket light bulbs are pushed in and then slightly rotated. The socket has two L-shaped slots and a small spring to keep the two locked together, while the base of the bulb has two pins on either side. Bayonet sockets are a good option in situations where vibration could cause Edison screw bulbs to become loosened because of the locking mechanism. Depending on the type of bayonet base bulb used, these sockets have one or two contact points at the bottom. The designation "BA" for bayonet bases is followed by a number that indicates the base's diameter in millimetres, followed by either a "s" or a "d" to indicate whether the base has a single or double contact.