When replacing your fluorescent tubes, it is important to make sure the connection to the socket is secure. It is also important to note that when installing T8 LED tubes, rewiring will be required. Therefore, anyone interested in installing a new light fixture should refer to a qualified electrician. Before you can assess your electrical outlet or receptacle, first make sure the problem is not the tombstone or socket of your light fixture.
Tombstones, also known as lamp holders, provide power to the light bulb. They are often referred to as sockets. In this guide, we will be using a combination of the terminology.
*Note* Shunted tombstones are ONLY found in T8 fluorescent tubes with Instant-Start ballasts.
There are two types of tombstones, shunted and non-shunted. In order to tell the difference between shunted and non-shunted sockets, you should use a voltage meter set to “continuity.” A shunted socket will beep indicating that the two contacts, on both sides, are connected. This means that there is power flowing through one side of the socket to the other side.
A non-shunted socket will not beep, indicating that the two contacts are not connected. If you would like to learn more about which tombstone you have, check out our Shunted vs. Non-Shunted Tombstone Guide
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