Shunted vs. non-shunted sockets: How to tell what you have

How do I tell if my sockets, or tombstones, are shunted or non-shunted? This is an important question to answer for linear fluorescent or LED light fixtures because it will ensure that you get maximum life out of your lighting and avoid dangerous fire hazards.

Before we start, we need to gather a few materials. First, we need the sockets in question. Second, we need a multi-meter. And finally, we need protection.

You may be able to tell what kind of sockets you have with a simple visual inspection.

The bottom of a shunted socket typically only has one set of electrical contacts –– or points of entry for the wires –– which means that the electrical contacts inside the socket are connected.

By comparison, the bottom of a non-shunted socket typically has two sets of electrical contacts –– or entry points for the wires –– which means that the electrical contacts inside the socket are probably not connected.

Looking at the electrical contacts may give you an indication, but the only way to be certain about the type of socket you have is to test with a multi-meter.

Before we get started, make sure that electricity is disconnected from your light fixture and sockets.

Next, make sure that the multi-meter is set to continuity, which essentially tells you if the circuit you’re testing makes a connected loop. You can test this by touching the multi-meter probes together, and the display will change.

Let's start with the shunted socket. Touch the multi-meter probes to the contacts where the tube pins go. The display changes, indicating that the circuit makes a loop. These contacts are joined, confirming that the socket is shunted.

Some multi-meters will also beep or light up when continuity is detected.

Now test the non-shunted socket. Again, touch the multi-meter probes to the contacts where the tube pins go. The display does not change, indicating that the circuit is broken, or separated. These contacts are not joined, confirming that the socket is non-shunted.

If you’re wondering which kind of socket you need for your specific fixture, watch our next video that gives an overview of the possible socket combinations for fluorescent and LED tubes:

   • Shunted vs. non-shunted sockets: How ...  

If you want more detail on the differences between these types of sockets, watch this video:

   • What’s the difference between shunted...  

If you have a project you're working on and you need to find the right socket and tube combination, contact us here, and we'd be happy to help:

https://info.regencylighting.com/what...