Shunted Versus Non-Shunted Tombstone (Socket)

By david_lu on 01/11/2017

Shunted, or non-shunted; that is the question: Whether ‘tis Nobler in the mind to suffer. The sockets and wirings of outrageous fixture, or to take arms against a sea of electricity...

OMG, I just want to know if my linear fixtures have the right tombstone for my new LED tubes.

LED Fluorescent Tube Replacement Guide

We are not going to bored you with the philosophy of the socket, but we need to give you the basic perspective between the two sockets in three basic steps

1.    What is a light socket for a linear tube?
The socket, also refer to as the tombstone, is the connector where you twist the LED tubes in

2.    Shunted versus non-shunted
Shunted sockets are basically a connected wiring configuration which create a single track for electrical current to flow from the ballast, through the tombstone, and to the lamp’s pin.

While non-shunted are configured with separate contacts creating two tracks for the electrical current to flow through independently. 


The best and safest way to differentiate between the two is to use a voltage meter to detect the electrical current.  Your voltage meter should light up or beep if the electrical contacts are shunted.  Make sure your voltage meter is set to “continuity”

3.    Which sockets are used with your fluorescent tubes
Now that you understand the difference between the two, how do you apply it?
We have put a cross reference table together to help you identify the right LED tubes for your fluorescent fixtures:

Shunted Tombstone

Non-shunted Socket

Most Electronic Ballast

Most Magnetic Ballast


T12 Fluorescent Tube

T8 Fluorescent Tube with
Instant Start Ballast

T8 Fluorescent Tube with
Rapid Start Ballast

T5 Fluorescent Tube with
Instant Start Ballast

T5 Fluorescent Tube with
Rapid Start Ballast

Ballast Compatible T8 LED Tube

Ballast Bypass T8 LED Tube

Hybrid T8 LED Tube

Hybrid T8 LED Tube


Please keep in mind that this guide is designed to help you better understand the difference between shunted versus non-shunted socket.  You should always consult a master electrician or your linear fixture manufacturer to determine which tombstone you have. 

Note that using the wrong type can not only shorten the life of your LED tubes, but could also cause an electrical short, resulting in a fire.

Shop all LED Tubes