T8-LED Retrofit Lamps Type B Replacement
This short tutorial walks through replacing fluorescent lamps in a T8 strip or channel fixture with four-foot LED Type B retrofit lamps. The example focuses on a direct-wire installation, which removes the ballast and connects line voltage directly to the lamp sockets. The work can be completed quickly when the fixture and wiring are suitable.
Key takeaways
Turn off power at the breaker before opening or rewiring any fixture.
Confirm whether the existing lamps are T8, T12, fluorescent, or LED.
Type B installation means the ballast is removed or bypassed.
Double-ended lamps are wired with one end connected to neutral and the other to hot.
Socket type, lamp instructions, and local electrical requirements must be checked first.
For commercial properties, use a qualified electrician when the wiring is unclear or the fixture is part of a larger lighting system.
Identify the fixture and existing lamps
A strip or channel fixture usually has exposed lamps and no lens. A wrap fixture is similar, but it includes a lens or cover around the lamps. The tutorial focuses on a basic strip fixture with one ballast and two lamps.
Before removing anything, inspect the fixture and read the lamp labels. Existing lamps may be:
Existing setup | What to check |
|---|---|
T8 or T12 fluorescent | Lamp size and ballast compatibility |
Type A LED | Designed to work with a ballast |
Type B LED | Requires direct wiring and ballast bypass |
Type A/B LED | May support more than one wiring method |
The replacement lamps shown are four-foot LEDs rated at about 14 watts, with a 5,000 Kelvin color temperature. Always follow the wiring diagram supplied with the specific lamp. Product designs vary, even when the lamps look similar.
Shut off power before starting
Switching off the wall control is not enough for safe electrical work. Shut off the circuit at the breaker, then verify that the fixture is not energized with an appropriate tester.
If the fixture is mounted to a ceiling or wall, the supply conductors may enter through the back of the housing. A corded shop fixture is useful for demonstration, but a permanently installed fixture should be handled with extra care. Preserve the equipment grounding connection throughout the work.
Remove the ballast cover and lamps
Remove the existing lamps by twisting them and pulling them from the sockets. Set them aside for proper recycling or disposal.
Next, open the ballast cover. On many strip fixtures, the cover is held by a small tab or screw at each end. Other fixtures may use several screws, so avoid forcing the cover if it does not release easily.
With the cover removed, locate the ballast and identify the wires running between it and the lamp sockets. Take a photo before cutting anything. It can help document the original layout, although the final Type B wiring must follow the new lamp manufacturer’s instructions.
Remove or bypass the ballast
For a direct-wire Type B retrofit, the ballast is taken out of the circuit. Cut the ballast wires close to the ballast, leaving as much usable wire length as possible at the sockets. Remove any mounting screw or retaining clip, then slide the ballast out.
Do not assume every fixture is wired the same way. Some systems use master-and-slave arrangements, multiple ballasts, or fixtures connected together. This tutorial applies to a single fixture with one ballast. A larger lighting system should be reviewed before any wiring is changed.
The fixture ground should remain connected to the building grounding system. If the ground conductor is damaged, missing, or difficult to identify, stop and have the fixture inspected.
Wire the Type B LED lamps
The example uses double-ended lamps. With this arrangement, one end of the lamp is connected to neutral and the opposite end is connected to the hot conductor. The socket wiring on each end is grouped accordingly.
A typical process is:
Strip the conductors to the length recommended for the connector being used.
Join the neutral supply conductor to the socket wires on the neutral end.
Join the hot supply conductor to the socket wires on the hot end.
Add a properly sized wire extension if a conductor is too short.
Secure every connection with an approved connector.
Keep the equipment grounding conductor connected to the fixture housing.
The wire colors shown in one fixture may not match another. Black is often hot and white is often neutral, but older or unusual installations can differ. Test and identify the conductors rather than relying only on color.
Socket designs also vary. Shunted and non-shunted sockets can affect some single-ended LED lamps. Double-ended lamps may be less sensitive to that difference, but the lamp instructions still control. Never mix wiring methods without confirming the lamp’s requirements.
Close the fixture and test it
After wiring, tuck the conductors neatly into the housing. Make sure no wire is pinched or exposed outside the ballast cover. Reinstall the cover and all screws, then install the LED lamps in the correct direction.
Restore power at the breaker and test the fixture. If the lamps do not light, turn the breaker back off before troubleshooting. Do not work on energized wiring.
For contractors, property managers, and hotel maintenance teams, standardizing on spec-ready LED SKUs can make repeat retrofits easier. Led Lumenaires supports commercial and industrial projects with bulk availability, volume pricing, product selection help, rebate guidance, layouts, and warranty support. That is useful when a small lamp replacement becomes a full building upgrade.
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