Shunted vs. Non-Shunted Sockets: What Option Do I Need?

Lighting is often a complex subject. We know that we want to have illumination in a dark room or outside in the evening, but what items actually go into the process of achieving that goal?


The one subject that tends to create the most confusion involves sockets. You have two options available when looking at this lead: shunted or non-shunted.


Knowing what sockets are needed for a linear lamp is crucial. If you use the wrong type, and electrical short can occur. This outcome would result in a fire hazard that would melt the tubes, sockets, or both.


Using the incorrect sockets can also void the UL listing on the lamp or shorten its lifespan.


Here are some of the guidelines to follow when you need to tell the difference between shunted vs. non-shunted sockets and when to use them.


What Are the Differences Between Shunted and Non-Shunted Sockets?


The word “shunted" implies that an item is connected or joined. When you have a shunted socket, it features electrical contacts with internal connections. This design ensures a single track for the current exists, traveling from the ballast through the socket (or tombstone) to the lamp's pins.


A non-shunted socket offers separate contacts. That means more than one point of entry for the wires is available to create dual tracks for the current to travel. This design offers contacts that are not connected or joined.


This visual difference is the primary way you can tell if you've got shunted vs. non-shunted sockets to use. A few exceptions do exist, so the safest way to tell what design is present when you can't tell visually is to use a voltage meter.


Most voltage meters will ring, beep, or light up if the electrical contacts are connected with shunted sockets.


Shunted sockets receive voltage through a single wire set that spreads to two contacts. With a non-shunted design, the sockets send voltage to each of the contacts through dual tracks.


When to Use Shunted vs. Non-Shunted Sockets?

With a basic understanding of how shunted vs. non-shunted sockets work, it's easier to determine when you'll need each one for your lighting needs.


Although you can find multiple tables and charts that give you individual examples of shunted vs. non-shunted needs, it depends more on the ballast used for the fixture.


When you're using fluorescent lights, almost all of them require a non-shunted design. The only two exceptions to this need involve instant-start ballasts. If you have a T8 fluorescent lamp, it can be non-shunted instead of shunted with an external wire.


Many LED designs are compatible with shunted or non-shunted sockets. If you have a plug-and-play product, it might require a shunted socket to operate correctly. Most others, including those that use a ballast bypass, are compatible with non-shunted sockets.


There is some risk involved if you don't purchase the correct sockets, so speak with a local lighting specialist if you have questions about your specific situation.


What If I Want to Use an LED Retrofit Lamp?


When you're upgrading to LED lighting in a home or at a business, it is usually easier to use retrofit lamps. These typically don't need a ballast to deliver a high start-up voltage as fluorescent technologies, and they come with two options.


You can typically find a plug-and-play or a direct wire design. The latter requires non-shunted sockets, while the former uses the other. Bypassing the ballast is essential for LED bulb operation, ensuring that it operates off the line voltage directly.


Your light needs are effectively met when choosing between shunted vs. non-shunted sockets. When you get the correct product, you'll enjoy all the perks that LED technology brings to modern illumination. ​


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