With different types of fluorescent fixtures, there will be a specific type of socket that connects the fluorescent tube to the fixture. These sockets can go by a variety of names including a tombstone, because of their shape, or also as a lampholder.
There are both non-shunted as well as shunted sockets, and it is essential to replace any existing parts or to set up new fixtures with the correct option. The shunted option will only require two wires, as it has an internal bridge, while the non-shunted lampholder will require four.
Typical Use
Generally, most shunted sockets will only have two holes on one side of the lampholder. This helps to eliminate the risk of using the wrong type of socket in the fixture, which can result in fixture failure or the possibility of electric shock.
For newer styles of fixtures, the instant start types of ballasts will be designed to use the shunted sockets. This is virtually always the case, but it is still highly recommended to check the particular fixture and to ensure that every shunted tombstone is the right option.
The other common type of ballast, known as the rapid start ballast, will use the unshunted or non-shunted lampholders. With a bit of knowledge, it is possible to convert a non-shunted lampholder into a shunted by creating a bridge with a short piece of wire between the two sides of the socket. This is also known as a jump as it copies the function of the internal bridge found in shunted sockets.
This is not meant to be a permanent solution, and it is always the best option to buy the correct component. Shopping online or at a local hardware store should allow you to quickly find the right component for your replacement or repair needs.
Switching Sockets
It is possible for an experienced electrician to be able to retrofit light fixtures to convert from shunted lampholders to non-shunted to use new tubes in old fixtures. However, as this retrofit does require an understanding of the systems and wiring, it is never advised to try this as a home project.
When replacing existing sockets look for part numbers on the socket to help to find the right replacement. It is also possible to work with a specialized fluorescent lighting parts specialist to find even hard to locate types of lampholders to get your lights back up and running.
