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Learning the ABCs of LED Tubes: Type A vs. Type B vs. Type C (and Dual-Mode)
- Michele Davidson
- Feb 5
- 6 min read
Replacing fluorescent tubes with LED lights (lighting retrofit) is one of the simplest ways facilities can cut energy use, reduce maintenance calls, and improve lighting quality. But LED tube retrofits aren’t one-size-fits-all.
When you start shopping, you’ll quickly see UL Type A, Type B, Type C, and Dual-Mode (Type A+B). Each option has its own installation method, long-term maintenance profile, and best-fit applications.
This guide breaks down what each type means, the tradeoffs that matter most, and how to choose the best solution for your facility.
First: What “UL Type” actually means
The “UL Type” classification helps define how an LED tube is powered and installed inside a linear fluorescent fixture:
Type A: Works off the existing ballast (ballast compatible / “plug-and-play”)
Type B: Bypasses the ballast and runs on direct line voltage (internal driver)
Type C: Uses an external low-voltage LED driver (ballast removed)
Dual-Mode (A+B): Can operate as Type A or Type B, depending on how the fixture is wired
Quick comparison: LED tube solutions by type
Here’s the high-level way to think about the four categories:
UL Type | How it’s powered | Biggest benefit | Biggest watch-out |
Type A (Ballast Compatible) | Existing fluorescent ballast | Fastest/easiest install | System depends on ballast health/compatibility |
Type B (Ballast Bypass) | Line voltage to lampholders | Avoids ballast failures | Requires rewiring + relabeling; limited dimming/control |
Type C (External Driver) | Dedicated external driver | Highest efficiency + best long-term reliability | Higher upfront cost; requires driver install |
Type A+B (Dual-Mode) | Works as A or B | Flexible for different site conditions | Must select correctly and follow safe retrofit practices |
UL Type A LED tubes (Ballast Compatible / “Plug-and-Play”)
What it is
Type A tubes are designed to operate on the existing fluorescent linear ballast. The LED tube has an internal driver that allows it to run using the ballast already in the fixture.
Why facilities choose Type A
Easiest installation: typically no fixture modification
Lowest initial disruption: great for fast turnarounds or phased upgrades
Key drawbacks to plan for
Type A retrofits are only as good as the ballast they’re paired with:
A ballast compatibility audit should be done before the retrofit
If ballasts are older or mixed across the facility, performance can vary
System longevity depends on ballast reliability
A failing ballast can create extra maintenance cost over time
If ballast and lamp don’t match well, you may see flicker or buzzing
Dimming capability may be limited by the ballast
Typical cost:
Tube cost often falls around $6–$13 per tube, with labor commonly in the $15–$30/hr range (and potentially additional cost if ballast replacement is needed).
UL Type B LED tubes (Ballast Bypass)
Keystone 11W T8 LED Lamp | 3000/3500/4000/5000/6500K | > 80 CRI | High-Efficiency | Single- or Double-ended Line Voltage Wiring
Keystone 7W T8 LED | 3500/4000/5000K | > 83 CRI | High-Efficiency | Single-Ended Wiring
Keystone 14.5W T8 Emergency Backup LED Tube | 2000 Lumens Standard / 500 Lumens Emergency | 4 ft | Color Select: 3000/3500/4000/5000/6500K | 120–277V Input | Individually Boxed
What it is
Type B tubes include an internal driver, but they are powered directly from mains voltage - meaning the ballast is bypassed and the fixture is rewired to feed power to the lamp holders.
Why facilities choose Type B
More efficient than Type A because the ballast is removed from the equation
Helps eliminate compatibility issues tied to ballast make/model
Avoids ongoing ballast replacement costs
Key drawbacks to plan for
Installation is more complex (requires electrical modification)
After conversion, the fixture can’t accept fluorescent tubes
The fixture should be properly re-labeled for end-user safety
Type B options can have limited dimming and control capabilities
Some environments (especially with power quality issues) may need extra consideration
Depending on product, wiring may be single-ended or double-ended, which affects installation requirements
Typical cost:
Around $8–$12 per tube, with labor commonly $20–$35/hr.
UL Type C LED tubes (External Driver)
Keystone 10W T8 LED Tube | Type C | 3000K–5000K | > 83 CRI | 0–10V Dimming
Keystone 15W T5 LED Tube | Type C | 3500–5000K | > 82 CRI | 0–10V Dimming
What it is
Type C tubes operate on an external low-voltage LED driver. The fluorescent ballast is removed, and the driver connects to the lampholders/sockets.
Keystone Constant Current Output | 120-277V Input | 0-10V Dimming
Keystone Constant Current Output | 120–277V Input | 0–10V Dimming
Why many facilities prefer Type C
Type C is often considered the most “purpose-built” retrofit path:
Often delivers the highest efficiency
Frequently offers the best long-term reliability
Can support dimming and controls more effectively
The driver isn’t crammed into the tube, which can reduce heat-related stress
Drivers and tubes can often be replaced independently, improving serviceability
Key drawbacks to plan for
Higher upfront material cost (driver + tube)
Requires fixture modification and relabeling
Best results come from good system design (matching driver/tube/control intent)
Typical cost:
Tube costs around $9–$14 per tube
Driver cost can be around $13–$18 per driver
Labor commonly $20–$35/hr
While upfront cost may be higher, Type C is a strong choice for the lowest long-term cost due to performance and maintenance benefits.
Dual-Mode (UL Type A+B) LED tubes
What it is
Dual-mode LED tubes are designed to run either as Type A (with a compatible ballast) or Type B (ballast bypass). They’re often used when facility conditions vary, and you want flexibility.
Why facilities choose Dual-Mode
Versatility across different fixture types and retrofit strategies
Lets you decide whether to keep the ballast or bypass it based on site needs
Some dual-mode products include internal safety features (lamp base is equipped with a thermal fuse that detects overheating and automatically shuts off the lamp)
Key drawbacks to plan for
Utility rebates can differ by type - if a rebate only covers one method (Type A or B), you may need to select/install accordingly.
Requires careful product selection and safe electrical practices.
Only qualified, trained electricians should perform installations/retrofits.
Typical cost:
Often around $8–$12 per tube, with labor commonly $15–$30/hr (varies by operating mode and site conditions).
Choosing the best LED tube retrofit for your facility
When we help customers select a tube type, we focus on four decision drivers:
1) What matters most: lowest upfront cost or lowest long-term cost?
If lowest upfront cost and speed are critical, Type A can be attractive.
If you want fewer future maintenance events and stronger system reliability, Type C is often the “design it right and move on” option.
2) What’s the condition and consistency of your ballasts?
Mixed ballast types across a building can complicate Type A projects.
Old ballasts can become a maintenance liability even after the tubes are upgraded.
3) Do you need dimming, controls, or lighting performance consistency?
Type C is typically best positioned for robust control strategies.
Type B may be limited depending on product/control goals.
4) Who is installing it - and what safety/labeling steps are required?
Any bypass or driver-based retrofit requires proper wiring, labeling, and workmanship.
A note on UL Listing and compliance
Your fixtures matter—not just your lamps.
Retrofitting an existing UL-listed fixture with a UL-classified retrofit kit results in a UL-certified installation - you can consult us for questions on UL certification.
If you’re managing a portfolio with compliance requirements (schools, healthcare, municipal buildings, etc.), it’s worth confirming the right documentation and installation practices before rolling upgrades across multiple sites.
Bottom line: The “best” LED tube depends on your site
Here’s a simple takeaway:
Type A = fastest install, but ballast-dependent
Type B = no ballast headaches, but requires rewiring and has control limitations
Type C = best long-term solution for many facilities, but higher upfront scope
Dual-Mode A+B = flexibility, but selection/install practices are critical
If you’d like, FTS can help you match the right solution to your fixture conditions, energy goals, maintenance strategy, and any rebate requirements—whether you’re upgrading a single building or standardizing across an entire portfolio.
Ready to plan an LED tube retrofit?
Contact the FTS “A” team to review your existing fixtures, identify the right UL Type approach, and build a retrofit plan that fits your timeline and budget.
To place an order: orders@ftslighting.com
Call: (800) 994-0440 | (714) 289-1957