Wiring 4-foot LED lights comes down to two approaches: a ballast bypass for retrofitting old fluorescent fixtures, or a plug-in shop light for fresh installations.
Or you’re finishing a basement and want bright, efficient lighting without the headache of ballasts that fail every few years. Either way, knowing how to wire 4 foot LED lights starts with one choice: are you retrofitting an existing fixture or starting from scratch? The method you pick determines every step that follows — and getting it wrong means a tube that won’t light or a short that kills the driver.
Which Wiring Method Fits Your Setup?
The right wiring path depends entirely on whether you’re retrofitting an existing fluorescent fixture or installing a brand-new light. Retrofitting requires a ballast bypass (direct wire) that removes the old ballast completely. New installations are simpler: most linkable shop lights just need a plug and an outlet. If you’re adding lighting specifically for plants or seedlings, our roundup of the best 4-foot LED grow lights covers tested plug-in options that skip the wiring entirely.
Ballast Bypass (Retrofitting an Old Fixture)
This is the most common project. You remove the ballast entirely and run line voltage directly to the lamp holders (tombstones). This is permanent — once rewired for LED, you cannot put fluorescent tubes back in.
Plug-In Shop Light (New Installation)
If you’re starting from scratch with no existing fixture, skip the ballast bypass. Buy a linkable 4-foot LED shop light with a power cord, mount it to the ceiling or joists, and plug it into a standard 120V outlet.
Here’s how the two methods compare across the factors that matter:
| Factor | Ballast Bypass (Retrofit) | Plug-In Shop Light |
|---|---|---|
| Best for | Existing fluorescent fixtures | New installs with no fixture |
| Wiring required | Removing ballast, rewiring tombstones | Just plug into an outlet |
| Cost per light | $15–$25 per tube | $40–$80 per fixture |
| Tools needed | Wire cutters, voltage tester, wire nuts | Screwdriver, drill (for mounting) |
| Permanence | Can’t go back to fluorescent | Reversible — unplug and remove |
| Linkable | No (each tube wired individually) | Yes (up to 6 fixtures per circuit) |
| Brightness per unit | ~1800–2400 lumens per tube | ~4500–5500 lumens per fixture |
How to Wire a Ballast Bypass for 4-Foot LED Tubes (Step by Step)
The ballast bypass process removes the old ballast and runs 120V directly to the tombstones. You must confirm your tombstones are non-shunted first — shunted sockets short the LED and destroy it.
- Kill the power. Flip the breaker for that circuit. Confirm zero voltage with a non-contact voltage tester at the fixture wires.
- Remove the cover and old tubes. Take off the troffer lens or strip cover. Remove the fluorescent tubes and set them aside for recycling.
- Disconnect the ballast. Open the ballast access cover. Cut all wires going into the ballast, leaving enough length on the incoming power wires (black and white) to work with. Remove the ballast from the fixture — you can leave the empty ballast box in place if space is tight, as long as all wires are disconnected.
- Check the tombstones. Look at the lamp holders. Non-shunted tombstones have individual wire entries for each pin. Shunted tombstones share a single wire entry for both pins. If yours are shunted (common in older T12 fixtures), replace them with non-shunted tombstones before wiring.
- Wire the hot side. Connect the incoming black (hot) wire to one side of the tombstones. For single-ended tubes (power at one end only), install a short jumper wire between the two tombstones on that side, then connect hot to one of them.
- Wire the neutral side. Connect the incoming white (neutral) wire to the opposite side of the tombstones.
- Ground it. Connect the bare copper ground wire to the fixture’s green ground screw or ground wire.
- Secure connections. Use wire nuts on every splice, and wrap each nut with electrical tape for extra security.
- Install the LED tube. Insert the tube with the end labeled L or AC Input facing the hot tombstone. The unlabeled end goes toward the neutral side.
- Test. Restore power at the breaker. If the tube lights smoothly, you’re done. If it flickers or stays dark, shut power off and recheck the orientation and tombstone type.
Electrical101’s direct-wire guide shows the connection diagrams for both single-ended and double-ended tube configurations if you want to double-check your wiring pattern.
Installing a Plug-In Shop Light (No Rewiring Needed)
Plug-in shop lights are the faster route when you don’t have an existing fixture. Most 4-foot linkable models mount directly to ceiling joists or drywall with included hardware.
Mount the fixture where you want it — garage ceiling, workbench, or grow room. Plug the power cord into a nearby 120V outlet. If the model is linkable, connect additional fixtures using the built-in connectors on each end. Most manufacturers limit the chain to 4–6 fixtures per circuit. Models like the PacLights 4FT LED Shop Light include a disinfectant-ready feature for commercial use, but the residential install is the same: mount, plug, link, flip the switch.
Common Mistakes That Kill LED Tubes
Three errors cause almost every failed LED tube installation. Here they are with the fix for each:
| Mistake | What Happens | The Fix |
|---|---|---|
| Shunted tombstones left in place | The two pins are shorted together, which can destroy the LED driver instantly | Replace with non-shunted tombstones before wiring (Step 4 above) |
| Tube installed backward | The AC input end sits on the neutral side — tube won’t light or flickers | Rotate the tube 180° so the labeled end faces the hot wire |
| Ballast not fully disconnected | Leftover ballast wires can back-feed or interfere even if the ballast is dead | Cut all wires to the ballast; remove it from the circuit entirely |
Wiring Checklist for 4-Foot LED Lights
Before you restore power, run through this sequence one last time: power is off at the breaker, tombstones are verified non-shunted, hot goes to the labeled end of the tube, neutral goes to the unlabeled end, all wire nuts are tight and taped, and the ground is connected. If every box checks, flip the breaker and enjoy light that lasts.
FAQs
Can I wire 4-foot LED lights to a dimmer?
Only if the LED tubes are explicitly labeled as dimmable. Standard T8 direct-wire tubes are non-dimmable, and connecting them to a dimmer switch will cause flickering, buzzing, or permanent damage to the driver.
Do I need to remove the ballast for LED tubes?
For direct-wire (ballast bypass) LED tubes, yes — the ballast must be completely disconnected from the circuit. Some plug-and-play LED tubes work with the existing ballast, but those are less efficient and the ballast is still a future failure point.
What’s the difference between single-ended and double-ended LED tubes?
Single-ended tubes receive power at only one end — the other end is a dummy holder. Double-ended tubes get hot on one side and neutral on the other. The wiring pattern differs: single-ended requires a jumper wire between the two tombstones on the powered side.
How many 4-foot LED lights can I put on one circuit?
Most linkable models draw 40–50W each, so the practical limit is wiring capacity, not tube count.
Can I rewire a T12 fixture for LED?
Yes, but you must replace the shunted tombstones common in T12 fixtures with non-shunted tombstones first. The wiring (ballast bypass) is identical to a T8 retrofit after the tombstone swap.
References & Sources
- Electrical101. “Direct Wire Double-Ended LED Tube Lights.” Connection diagrams and wiring patterns for single-ended and double-ended T8 LED tubes.