You have three ways to move a linear fluorescent fixture to LED: a Type A tube that runs on the existing ballast, a Type B tube installed after the ballast is bypassed and the sockets are wired to line voltage, or a new LED fixture. Type A is the quickest swap, but only when the tube is listed as compatible with your exact ballast. A dead ballast then takes the tube with it. Type B removes the ballast but requires rewiring the fixture with a certified kit. Replacing the fixture is often the cleanest choice when it’s old or damaged.
The options
UL’s retrofit FAQ defines the tube types:
| Path | What UL says | What to confirm |
|---|---|---|
| Type A (ballast-compatible) | For direct substitution, running from the fixture’s ballast without modifying the fixture | The tube maker’s compatibility list includes your ballast model |
| Type B (ballast-bypass) | For fixtures whose fluorescent lampholders are wired directly to the branch circuit | The tube and kit are certified for retrofit use, wiring is done correctly, and the fixture is labeled |
| Type A/B hybrid | Certified to UL 1993 as a lamp; to be used for a conversion, it must also be investigated to UL 1598C as part of a retrofit kit, with a dual mark | The dual certification mark |
| New LED fixture | Not a retrofit | Mounting, supply, location rating and controls |
UL says certified retrofit kits include field-applied labels to stick on the fixture after conversion. Those labels tell the next person which lamp type the fixture now takes. Never put a fluorescent tube or a Type A tube into a fixture that has been rewired for Type B.
Rewiring a fixture is electrical work. Follow the certified kit’s instructions or hire an electrician. Don’t use a generic bypass diagram from a different product.
Diagnose a dead fixture before buying
A dark, flickering or buzzing fixture can have a bad tube, a failing ballast, a loose connection or a switch problem. A new tube won’t help if the ballast is the problem, and a Type A tube needs a working ballast. Stop using a fixture that shows scorching, melted insulation or a burning smell.
Compare light and cost
Match the light output in lumens, color temperature and glare, and check dimmer or sensor compatibility. A new tube can look different from the old lamp behind the same diffuser. To estimate savings, multiply the watt difference, including any ballast you keep, by your hours of use and your electricity price.
Dispose of fluorescent tubes properly
Fluorescent tubes contain mercury. Recycle them through a local program (EPA disposal guidance ). If one breaks, keep people and pets out of the room and follow EPA’s broken-bulb cleanup steps .