LED Ballast Bypass Tubes: Match the Wiring Before Buying
Choose Type B LED tubes by supply voltage, single- or double-ended wiring, lampholders, fixture fit, dimming and retrofit certification.
LED ballast bypass tubes are Type B lamps: they operate from the branch-circuit supply rather than through a fluorescent ballast. They require a fixture wired for that purpose. Matching the tube’s length and pins is not enough—you must also match its input voltage, single- or double-ended power arrangement, lampholders and permitted fixture construction.
This is a line-voltage fixture conversion, not a 12 V or 24 V LED-strip project. Have a qualified electrician assess and perform the conversion; check local permit and installer requirements. UL explains both Type B operation and jurisdiction-dependent retrofit requirements.
Identify the tube type first
“LED replacement tube” does not identify how the lamp receives power.
| Tube designation | Power arrangement | What it means for the existing fixture |
|---|---|---|
| Type A | Existing compatible fluorescent ballast | No ballast-bypass conversion; check the lamp manufacturer’s ballast compatibility list |
| Type B | Branch-circuit supply at the lampholders | Ballast must be disconnected from the lamp circuit; fixture wiring must match the tube |
| Type A/B, or hybrid | Compatible ballast or direct supply | Follow the instructions for the chosen operating mode |
| Type C | Separate LED driver | Requires a matched driver-and-tube conversion, not Type B wiring |
These distinctions are described in UL’s luminaire retrofit guidance. For hybrid lamps, ballast compatibility still matters in Type A mode: LEDVANCE requires an approved lamp-and-ballast combination.
A Type A-only tube is not a direct-wire replacement. Likewise, do not put a Type B-only tube into an unchanged ballast-fed fixture.
Single-ended and double-ended are not interchangeable
The important distinction is where the supply connects, not whether the tube has pins at both ends. For common bi-pin Type B tubes:
| Power arrangement | Supply connection concept | Lampholder requirement |
|---|---|---|
| Single-ended | Line and neutral connect to separate contacts at one designated end; the other end supports the lamp | The powered lampholder must be non-shunted |
| Double-ended | Line connects at one end and neutral at the other | Follow the exact lamp instructions; some products accept either socket type, with specified wiring |
| Supports both | Either arrangement is permitted under the product’s instructions | Requirements change with the selected arrangement |
A shunted lampholder electrically joins its two lamp-pin contacts. A non-shunted lampholder keeps them separate. Connecting line and neutral to contacts that are joined would create a short circuit. Do not infer the socket type from appearance alone; have the installer verify it. Parmida explains the electrical distinction, while RAB’s single-ended retrofit instructions require non-shunted lampholders.
Double-ended does not mean “any socket wiring will work.” For example, LEDVANCE’s color-selectable DUALescent instructions allow existing sound lampholders but require non-shunted holders to be externally shunted for double-ended operation. They require non-shunted holders for single-ended operation. That is a product-specific requirement, not a universal wiring recipe. See the manufacturer’s installation guide.
What to check before ordering
Use the exact model’s specification sheet and installation manual, not just the listing title.
- Supply voltage: Confirm the fixture’s actual supply and the tube’s direct-wire rating. Some North American products are rated 120–277 V AC; do not assume every bypass tube has that range. An old ballast’s rating is not proof of the new lamp’s rating.
- Physical fit: Match lamp length, base, socket spacing and clearance. A G13 bi-pin base does not by itself establish electrical compatibility.
- Host fixture eligibility: Check permitted fixture types, lamp quantity and compartment dimensions. Tube fit alone does not establish an approved retrofit; UL describes these host-fixture criteria.
- Condition: Have the installer inspect sockets, wiring and the housing. Damaged parts need correction, not concealment behind new lamps.
- Light output: Choose lumens and color temperature separately from wattage. Check distribution and diffuser suitability as well as nominal brightness.
- Environment: Verify location and ambient-temperature ratings. “Damp location” does not mean suitable for direct water exposure.
The LEDVANCE fixed-color-temperature DUALescent specification illustrates why these checks belong together: it specifies voltage, lengths, output, location limits and operating temperature, and warns that poor lamp insertion can cause arcing and localized overheating.
Check controls and emergency lighting separately
Bypassing the ballast does not automatically preserve dimming or emergency operation.
For example, RAB’s single-ended tubes cited here prohibit dimmers. The fixed-color-temperature LEDVANCE DUALescent family cited here uses a specified 0–10 V module for Type B dimming. These examples do not establish the requirements for other models, including color-selectable versions. A “dimmable” label needs a documented control method and compatible equipment—not an assumption that an ordinary wall dimmer will work.
If the fixture has emergency backup, have the electrician verify a supported emergency configuration before selecting tubes. The fixed-color-temperature DUALescent specification requires the existing fluorescent-system emergency ballast to be disconnected from the lamp in Type B mode. Do not treat an emergency fixture as an ordinary tube swap.
The finished fixture needs a label
The conversion should follow the certified retrofit instructions, including ballast disconnection or removal, lampholder changes, grounding, enclosed connections and the supplied relamping label. RAB’s instructions include these conversion requirements. After conversion, do not reinstall fluorescent lamps or assume another LED tube is compatible. Keep the approved replacement model and wiring arrangement documented for future maintenance.
UL says a suitable certified retrofit kit installed according to its instructions can maintain compliance with the host fixture standard. For UL-certified A/B conversions, a lamp’s Listing mark alone is not sufficient evidence of retrofit evaluation; UL distinguishes lamp certification from retrofit-kit certification.
Ballast bypass is worth comparing when the housing is sound and the conversion is well documented. Price the tubes, labor, socket work and any control or emergency changes together. If retaining the fixture requires substantial repairs, compare the other LED replacement options for fluorescent fixtures before committing.