Types of LED tubes: Type A, Type B ballast bypass and Type C compared
There are three main types of LED tubes for fluorescent fixtures. Type A runs on the existing ballast, Type B (ballast bypass) runs directly on line voltage, and Type C uses an external driver. The type decides install labor, energy savings, safety and whether your utility pays a rebate.
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Type A, Type B or Type C: what is the difference?
All three replace fluorescent tubes in the fixtures you already have. What changes is where the power comes from: the old ballast (Type A), line voltage straight to the sockets (Type B), or a new external driver (Type C). That one choice sets the install labor, the energy savings and the safety rules.
| Type A | Type B | Type C | |
|---|---|---|---|
| How it runs | On the existing fluorescent ballast | Directly on line voltage, ballast removed | On an external LED driver that replaces the ballast |
| Electrician needed | Usually not | Yes | Yes |
| Energy savings vs fluorescent | About 20% | 30 to 50% | 30 to 50% |
| Install time per fixture | Under 5 minutes | About 15 minutes | About 15 minutes or more |
| What you replace later | Ballast and tubes | Tubes only | Tubes and driver |
| Safety | Low shock risk | Highest risk of the three: line voltage at the sockets | Lower voltage from driver to sockets |
Savings and install times from the U.S. Department of Energy guide for schools (November 2024), based on PNNL estimates. Retrofit kits and new LED fixtures save 40 to 60%. Hybrid Type A/B tubes run either way: on the ballast today, direct wire later.
Where the power goes in each tube type
Follow the path from the building wiring to the tube. The box in the middle decides everything else.
Sockets stay wired to the ballast. The tube must be listed as compatible with that ballast.
The sockets carry line voltage. The fixture is rewired by an electrician and labeled.
The sockets carry only the low-voltage output of the driver. One driver can power several tubes.
Runs on a compatible ballast now. When the ballast fails, an electrician bypasses it and labels the fixture.
Type A LED tubes: plug and play on the existing ballast
A Type A tube has a built-in driver designed to run on a fluorescent ballast. You take out the fluorescent tube and put in the LED tube. There is no rewiring, so maintenance staff can usually do it.
The catch is the ballast. The tube only works properly on ballasts its maker has tested, so check the compatibility list against the ballast label. The ballast keeps drawing power and will fail one day, and then you replace a ballast to keep an LED tube running.
A good fit when
- The ballasts are electronic, fairly new and on the tube's compatibility list
- You need a quick swap without an electrician
- The fixtures are due for replacement in a few years anyway
Think twice when
- The ballasts have been in use for 5 years or more: DOE does not recommend Type A tubes on them
- You want dimming: Type A tubes may not be dimmable
- You want the highest savings: about 20%, because the ballast limits efficiency
Type B ballast bypass tubes: direct wire to line voltage
A Type B tube has its driver inside and runs directly on line voltage. An electrician removes or bypasses the ballast and rewires the sockets to the building circuit. This is what people mean by ballast bypass or direct wire LED tubes.
Savings are higher, 30 to 50% versus fluorescent, and there is no ballast left to fail, so later you only replace tubes. In return the conversion takes about 15 minutes per fixture, needs an electrician and puts line voltage at the sockets.
Single-ended or double-ended wiring
Line and neutral at the same end of the tube. Needs non-shunted sockets at the powered end. A single-ended tube in shunted sockets causes a short circuit.
Line at one end, neutral at the other. Many double-ended tubes work with shunted or non-shunted sockets, but requirements differ by product, so follow the wiring diagram of the exact tube.
What a safe ballast bypass looks like
- A UL classified retrofit kit or a tube certified for conversion (UL 1598C), installed per its instructions
- A qualified electrician does the work
- Sockets match the wiring: non-shunted for single-ended tubes
- A label on every converted fixture says it can no longer take fluorescent tubes
- One tube type per building: DOE advises against mixing Type A and Type B
DOE does not recommend Type B tubes in schools that often see power surges or interruptions.
Type C LED tubes: an external driver replaces the ballast
Type C tubes have no driver inside. An electrician replaces the ballast with an external LED driver, and the sockets receive only the driver's low-voltage output. One driver can run several tubes.
DOE rates Type C as the most efficient tube option and safer than Type B, because the sockets do not carry line voltage. Some drivers offer 0-10V dimming, which makes controls easier. Later you stock two parts, tubes and drivers, and the two work as a system.
Hybrid Type A/B tubes
Hybrid tubes run on a compatible ballast now and directly on line voltage after a bypass. That lets you swap tubes today and remove ballasts as they fail.
Use a hybrid tube for a conversion only if it is certified for that use, and label the fixture once it is rewired.
Changing T12 to LED
T12 tubes are 1.5 inches thick, T8 tubes 1 inch and T5 tubes 5/8 inch. Many T12 fixtures still run on old magnetic ballasts, and that changes the choice.
- Standard T8 Type A tubes are built for electronic T8 ballasts. T8 lamps run at 265 mA, T12 lamps at 430 mA. On a magnetic T12 ballast you need a tube that is specifically listed for that ballast, or you bypass the ballast.
- Federal standards phased out magnetic ballasts for full-wattage T12 lamps between 2005 and 2010, so most magnetic T12 ballasts still in service are far past the 5 years at which DOE stops recommending Type A tubes.
- Utilities lean the same way: Snohomish PUD in Washington lists only Type B and Type C tubes for T12 conversions.
- T12 magnetic ballasts made before July 1, 1979 may contain PCBs. If a ballast has no "No PCBs" label and you cannot show it was made later, EPA advises to assume it contains PCBs and handle it accordingly.
Federal efficiency rules that took effect in July 2012 eliminated most 4 ft T12 lamps. In Oregon the sale of linear fluorescent tubes has been banned since January 1, 2025 (public school districts, education service districts and owners of more than 1 million square feet of Oregon facilities have until January 2, 2030), and Washington's ban starts January 1, 2029. Details in our fluorescent light ban guide.
How to tell what you have before you order
A look at one fixture of each kind answers most questions. Switch off the power first.
Read the lamp
F32T8 means a 32 watt fluorescent tube, 1 inch thick. F40T12 means 40 watts and 1.5 inches.
Read the ballast label
Note electronic or magnetic, the start type (instant, programmed or rapid start), the ballast factor and the input voltage. Match them against the tube maker's compatibility list.
Check the sockets
Instant-start fixtures have shunted sockets. Rapid-start, programmed-start and magnetic fixtures have non-shunted sockets. A multimeter continuity test confirms it.
Send us a photo of the lamp and the ballast label, and we tell you which tube types fit.
Do LED tubes qualify for rebates?
Sometimes. Most programs require the exact tube model to be listed by the DesignLights Consortium (DLC) or ENERGY STAR, and programs treat the tube types differently. Some pay the same for all types, some pay more for Type B and C, and some pay for tubes only in limited cases.
| Program | How it treats tube types | Published amount |
|---|---|---|
| Energy Trust of Oregon (PGE, Pacific Power) | Standard incentives no longer cover LED tubes. LED tubes are listed only in the instant discount for public K-12 schools. DLC 5.1 or ENERGY STAR required. | $2.50 to $9.50 per lamp (K-12 schools, checked November 2026) |
| Puget Sound Energy (WA) | Same amount for all types. DLC listing required, retrofit projects only. | $4 per 2 to 4 ft T8 lamp, $6 per 8 ft lamp, through December 31, 2026 |
| JCP&L (NJ) | Type A, B, A/B and C in one category. DLC "Linear Replacement Lamps" listing with a printout as proof. | Per lamp, see our JCP&L page |
| Clark Public Utilities (WA) | Pays more for bypass and external driver tubes. | 4 ft T8: Type A $2, Type A+B, B or C $4 |
| Snohomish PUD (WA) | Pays more for Type B and C. T12 conversions only as Type B or C. | Type A $1, Type B or C $4 per tube |
For other Oregon buildings, Energy Trust incentives now go to LED fixtures and retrofit kits rather than tubes. See Oregon lighting rebates, PSE business lighting and all programs.
LED tubes from LED Light Source
Our tube range covers the common retrofit cases:
- Premium EDI 4 ft tube: hybrid, installs as Type A on a compatible ballast or as single-end or dual-end bypass
- LED T5 tube (Type B): ballast bypass, single or double end wiring
- Premium 4 ft LED tunable tube: single or double ended wiring, selectable wattage and color temperature
See all LED tubes. Planning on a rebate? Ask us for the DLC listing of the exact model before you order.
Questions about LED tube types
Can I put an LED tube in a fluorescent fixture?
Yes. A Type A tube goes straight in if it is listed as compatible with the existing ballast. Type B and Type C tubes need the fixture rewired by an electrician, and the converted fixture gets a label. For a code-compliant conversion, UL points to certified retrofit kits, which keep the fixture's original listing.
Do LED tubes need a ballast?
Only Type A tubes. Type B tubes run directly on line voltage with the ballast bypassed, Type C tubes run on an external LED driver, and hybrid Type A/B tubes work either way.
What happens if I put a Type B tube in a fixture with a ballast?
Manufacturers do not allow it, and the tube will not work as intended. The reverse is a problem too: a fluorescent tube in a converted fixture can damage the tube or the socket, which is why converted fixtures are labeled.
Is ballast bypass safe?
Yes, when it is done right, but it carries the highest risk of the three types because the sockets carry line voltage. Use certified products, a qualified electrician, sockets that match the wiring, a label on every fixture and one tube type per building.
Which LED tube type saves the most energy?
Type B and Type C save about 30 to 50% compared with fluorescent, Type A about 20% (DOE, based on PNNL estimates). Retrofit kits and new LED fixtures save 40 to 60%.
Are T12 fluorescent tubes still sold?
Federal efficiency rules that took effect in July 2012 eliminated most 4 ft T12 lamps. Oregon has banned the sale of linear fluorescent tubes since January 1, 2025, and Washington's ban starts January 1, 2029. LED tubes listed for T12 fixtures are still available.
Can I mix Type A and Type B tubes in one building?
DOE advises against it for safety. Pick one type per building so nobody puts a tube into the wrong kind of fixture.
Get the right tube for every fixture
Tell us where your building is and who your utility is. We check what you have, which tube type fits and whether a rebate applies, at no cost and with no obligation.
Sources: U.S. DOE, LED guide for schools (2024); UL Solutions, retrofit kit FAQ; LEDVANCE, LED tube types; LEDVANCE, shunted vs non-shunted sockets; Westinghouse, Type B instructions; Lighting Research Center, T8 lamps; Lighting Controls Association, T12 ballasts; EPA, PCB ballasts; Energy Trust, 2025 lighting offers; Energy Trust, instant discounts; PSE, Lighting to Go; JCP&L incentive guide; Clark Public Utilities; Snohomish PUD; Oregon HB 2307; Washington Department of Ecology. Incentives are subject to program rules and funding availability. Figures checked November 2026.