You may have learned by now that lighting can be complicated. Non-shunted and shunted lampholders, also known as tombstones, is a topic that send many consumers running for the hills. In fact, some avoid the topic like the plague.
However, the time has come to quell those fears. In fact, there is a simple way to learn the difference between shunted lampholders and non-shunted lampholders. It is also just as simple to determine which is right for your application as well. Just like that lighting becomes a little less complicated.
It is of the utmost importance to determine which lampholders you need. If you use the wrong ones, the UL listing on the lamp will be voided. However, the greatest risk is causing an electrical short that could become a serious fire hazard of melted sockets and tubes. Moreover, if you do not use the proper lampholders, the life of the lamp will be shortened considerably.
The Difference between Non-Shunted and Shunted Lampholders
To many people, hearing the word “shunted” leads to thoughts of “connected” or “joined”. A shunted lampholder features electrical contacts that are connected internally. The result is a single track that allows the electrical current to move from the ballast, through the lampholder and on to the lamp pins.
The non-shunted lampholder features separate contacts, which are the wires’ points of entry. This creates two tracks where the electrical current can travel. Therefore, the contacts of a non-shunted lampholder are not joined or connected.
Overall, the safest and most effective way to determine the type of lampholders you have is with a voltage meter that is turned to “continuity”. Typically, a voltage meter will ring, beep or light up when the electrical contacts connect. This means you need shunted lampholders.
Shunted lampholders get voltage from a single set of wires that is then spread to two separate contacts. Meanwhile, non-shunted lampholders use two wire tracks to send the voltage to each contact.
Non-shunted lampholders are specifically wired in a series for use with a program start or rapid start ballast. It is possible to alter a non-shunted lampholder to a shunted lampholder for an instant start ballast externally with wires. However, you will be better off to purchase new shunted lampholders in order to avoid all of the unnecessary wiring work. This is especially the case if you have a considerable number of lampholders that you are considering shunting manually.