Posted by Doug Root on 2nd May 2016

Direct Wire LED T8 Tube Lights and What You Need to Know About Sockets.

Everyone can benefit from having LED lights in their home, but not everyone is gifted with the same level of technical know-how. If you’re looking to make the switch to LED but you need some help wiring T8 LED bulbs, read on to learn more about the installation process of LED tube fixtures. We will try to give you a good understanding of non-shunted sockets and the powering of these lamps using these helpful tips and the LED tube light connection diagram below.



Non Shunted

Non Shunted

Non Shunted and Shunted Sockets

Non Shunted and Shunted Sockets

1. Most common type of sockets are
non-shunted and shunted. Non-shunted on the left
and Shunted on the right side.
Verify the type of socket, or ‘tombstone’.

2. Typical wiring for
Side, the other Socket
will have no Power.

3. To confirm which type of socket is in the existing fluorescent
fixture, a voltage meter should be set to “continuity”. If the two
tombstone socket contacts show positive continuity, power flows
between the contacts and the socket is shunted.

What You Need to Know About Fixtures for Tube Lights and Shunted Sockets

Some shunted sockets may have 2 entries, like the non-shunted socket, or tombstone. The contacts in shunted sockets connect directly at the socket so power moves from one contact to the other.

As a general rule,T8 fluorescent fixtures with an instant start ballast have non-shunted sockets, and T12 fluorescent fixtures with a rapid start ballast usually have shunted sockets. However, it’s best to use a voltage meter to test "continuity." If the two socket contacts show positive continuity, power flows between the contacts, and the socket is shunted. This is an important part of understanding the fixtures of these tube lights.

Shunted sockets must be replaced with a non-shunted type for the ballast bypass single end live power LED retrofit lamp to operate properly. If there is no continuity across the contacts, the tombstone sockets are non-shunted and can be used with the LED tubes.

We call these types of installations hard wired, ballast bypass, or direct wire. After replacing the LED light sockets or verifying you have the correct socket, we’re ready to move on. For this application of fixtures for tube lights, one socket will have the live power and the other socket will serve solely as a lamp holder. This is shown in the following image which features the LED tube light connection diagram. No power will be run to the other end (the diagram below is for single end LED T8 ballast bypass lamps).

Non-Shunted Sockets

When wiring single end power  T8 LED bulbs, you must use non shunted sockets. The non-shunted socket will allow you to utilize single end power LED bulbs. With shunted sockets you are utilizing both sockets to complete the circuit. With non-shunted sockets you can rewire and run power to one live end - excepting the 120 or 277V circuits. These make a nice alternative for those wanting a simpler time with their fixtures for tube lights.

LED Direct Wire System | Pros & Cons

  • Pros – No need to replace or maintain the ballast.
  • Cons – Safety concerns over someone down the line putting in a fluorescent tube.

If this occurs, it could possibly malfunction or explode due to the direct line current not being regulated through a ballast. Currently there is a sticker that installers are instructed to apply at the time of the retrofit to alert that the wiring of the LED bulbs has been altered. This method is also labor intensive and may void the UL classification. Relabeling required.

*Power must be turned OFF, and it is recommended that a qualified electrician do the install.

It is imperative that one understands the system they are working with when retrofitting a fluorescent system to an LED direct wire system. For those of you who want to simply go LED but do not want to hassle with wiring T8 LED bulbs, then the " plug and play" option is the one you want.

Trusting the Experts

This is complicated stuff, but at Atlanta Light Bulbs, we know it all like the back of our hands. Get in touch with us now for everything you need to know about buying and installing fixtures for your tube lights. You can trust Atlanta Light Bulbs for perfect installation when it comes to LED light sockets and so much more.

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