Posted by Doug Root on 18th Aug 2015

Looking to Replace Fluorescent Tubes with LED T8 Lamps

Fluorescent Light LED T8 Replacement Tube Options

Hard Wire VS Direct Replacement Philips InstantFit Lamps

There are 2 main types of LED T8 replacement tubes on the market. We’ll explore the various technologies and pro’s and con’s to give you a good base understanding to navigate the retrofit market place.


Direct Replacement LED Tubes such as the Philips Instantfit LED Tubes – These are the latest product to the T8 LED marketplace that allow for you to just put them in as you would a replacement fluorescent tube that works directly with the existing electronic ballast.

Philips LED T8 Light


The Philips InstantFit LED T8 lamp is a simple way to instantly make your current fluorescent application more efficient. These energy-saving LED solutions seamlessly fit into existing linear fluorescent fixtures without any extra effort and utilize the existing ballasts, thus requiring no re-wiring upon installation. Because Philips offers InstantFit LED T8 lamps in a variety of lamp lengths and light levels, it is the simplest LED upgrade for fluorescent systems. InstantFit works with 80% of the installed T8 electronic ballasts*. Philips InstantFit LED T8 lamps offer the ideal balance of light quality, efficiency and compatibility.


Philips InstantFit LED T8 lamps make upgrading to LED easy. Using InstantFit LED lamps, users can replace existing T8 fluorescent lamps with without re-wiring, because the lamp uses the existing electronics. This solution minimizes maintenance and labor costs. This lighting solution is ideal for users focused on maximizing the value of an existing ballast investment.


Philips InstantFit LED T8 provides users with significant energy savings – up 40% when with compared traditional fluorescent 32W T8 systems. This lower energy consumption makes it easier to upgrade to LED by enabling financial short payback periods. (Actual savings depend on your unique system configuration.)


Compatibility means the lamps works as intended and Philips has tested InstantFit lamps with numerous electronic T8 ballasts to confirm performance. The InstantFit LED lamps are compatible with most electronic instant-start T8 ballasts as well as some program-start T8 ballasts.


Philips InstantFit LED T8 lamps contain no mercury and virtually no UV or IR light. Waste is minimized since these lamps are installed in existing luminaires.


Non Shunted Sockets
1.Most common type sockets.
Non-shunted on the left and 
Shunted on the right side. 
Verify the type of socket.
Shunted and Non Shunted
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
socket contacts 
show positive continuity, power flows
between the contacts and the socket is shunted

Non-shunted & Shunted sockets

Some shunted sockets may have 2 entries like the non-shunted socket. The contacts in shunted sockets connect directly at the socket so power moves from one contact to the other. Of note: the “shunt” may be internal to the socket and may not be view-able like in the picture above. Before installation you must confirm which type of socket is in the existing fluorescent fixture. 

As a general rule in T8 fluorescent fixtures with instant start ballast have non-shunted sockets and in T12 fluorescent fixtures with rapid start ballast usually have shunted sockets. However 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. 

Shunted sockets must be replaced with non-shunted type for the LED retrofit to operate properly. If there is no continuity across the contacts, the sockets are non-shunted and can be used with the LED tubes.

We call this type installations hard wired, ballast bypass or direct wire. The power is on one end No driver or ballast required, the driver is internally located inside of the plug and play or direct wire bypass tube light. After replacing the sockets one socket will have the live power feed as pictured in fig 2 and the other socket will serve solely as a lamp holder. NO power will be run to the other end.

The reason T8 LED requires non-shunted sockets is that the LED lamp is single end-powered. With shunted sockets, they work with fluorescent because you can utilize sockets on both ends of the fixture to complete the circuit. With LED you'd to put live AND neutral into the same side of the same socket, which would not work. With non shunted sockets you can rewire and have 1 end live accepting the 120 or 277V circuit. 

Pros – No need to replace or maintain the ballast any longer

Cons – Safety concerns over someone down the line putting in a fluorescent tube and it malfunctioning or possibly exploding due to the direct line current not being regulated through a ballast. Currently there is a sticker that installers are instructed to be apply at the time of the retrofit to alert that the wiring has been altered.

This method is also labor intensive and requires a licensed electrician and may void the UL classification of the fixtures.