Watts Up With Light Bulbs? Part 3: Sockets

Watts Up With Light Bulbs? Part 3: Sockets

How many people does it take to screw in a light bulb? Only one, if you can find the right replacement light bulb in the first place!

As we’ve discussed in this series on new light bulb technologies, many different bulb options have been produced to replace the familiar incandescent bulbs. Some of the changes in bulbs mean changes in the base shape, which is where the bulb connects to a socket. In order to replace a bulb, you still need to find one that fits the socket in your light fixture. Here is a rundown of the most common socket types, as well as adapter choices if you need to fit a new bulb in an old socket.

Screw Base Bulbs and Sockets

The most familiar type of light bulbs for many consumers is the screw base bulb. Many standard lamps and wall-mounted or ceiling-mounted light fixtures have screw base sockets. This type of bulb base is given a number such as E12, E17, and so on. “E” is for Edison, who invented the first screw base light bulb. The number refers to the size of the base in millimeters. Candelabra light bulbs are typically sized E12, while other fixtures are most commonly E26.

Screw base bulbs and sockets are standardized enough that generally, you don’t need to worry too much about finding the right type of bulb to fit a socket. However, if you have a specialized light with a non-standard socket size, you’ll need to make sure you know the right size in order to find the correct replacement bulb.

Pin Base Bulbs and Sockets

Pin base bulbs are somewhat less common than screw base bulbs, except in one area: commercial lighting that uses long fluorescent bulbs (properly called “linear fluorescents”), which are made with pin bases. Sockets for pin base light bulbs have slots for the pins to slip into; the pins lock into place to hold the bulb securely and keep it connected to the electrical current. Again, the name of this type includes information about the size of the base in millimeters, though in this case the number describes the distance between the two pins.

Most compact fluorescent light bulbs produced now for consumer lighting have familiar screw bases, but some CFLs are made with plug-in pin type bases.

Socket Adaptors

Because there is variation in the types of sockets used for light bulbs, there are socket adaptors available to help you properly and securely fit bulbs. Not every type of bulb base can be adapted to every kind of socket, but if an adaptor is available, using one can give you a lot more versatility in the types of light bulbs you can use.

One of the most common kinds of adaptor is one that simply adjusts the size of a screw base so that differently sized bulbs can be used with a light fitting. For example, you can use an adaptor to install “regular” sized light bulbs in a candelabra fitting by using an adaptor that has a screw type candelabra base at one end and a larger light bulb socket at the other.

There are other types of adaptors which add additional sockets or other features. For example, you can purchase an adaptor that enables you to use two bulbs from a single light socket, an adaptor that enables you to plug a light bulb straight into a power outlet for fast light, or one that adds a standard electrical socket to the side of a light socket.

One of the primary concerns with using adaptors is to make sure you don’t overload the fixture by using bulbs that draw too much electricity. Just as it may not be safe to screw a 100-watt bulb into a 60-watt light fixture, even though the base type is the same, it is not safe to use an adaptor to install a bulb type that draws too much wattage from a given light socket.


  1. LED Things You Need to Know When Buying says:

    […] Watts Up With Light Bulbs? Part 3: Sockets (blindsaver.com) […]

  2. Nancy Moshier says:

    We have a decorator small floor lamp that needs a socket replacement. We purchased a standard replacement but it was too small to fit the threads. Where can we find a proper replacement ?

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About the Author: Alicia Graham

Alicia Graham is the Product Manager for BlindSaver.com. She is also an experienced set designer and interior painter, with a broad knowledge of painting techniques that ranges from faux painting to alternate tools that save time and headaches. She is dedicated to making the imagination work in step with the budget and turning hobbyists into artists. Alicia Graham believes that anyone can be an artist in their home with a little help and information.