LED Ballast Bypass Wiring Diagram: How to Wire LED Tubes Without a Ballast
This is a free printable led ballast bypass wiring diagram: download the diagram as SVG or open it and print to paper or PDF.
An LED ballast bypass wiring diagram shows how to remove or disconnect a fluorescent ballast and wire mains voltage directly to the lamp-holder pins so an LED tube can operate safely.
Fluorescent tube luminaires rely on a magnetic or electronic ballast to limit current and start the arc. LED replacement tubes come in three categories: Type A (ballast-compatible, plug-and-play), Type B (direct-wire, bypasses the ballast), and Type A+B (dual-mode). A ballast bypass conversion — also called a direct-wire or Type B installation — removes the ballast from the circuit entirely and connects mains line and neutral voltage directly to the lamp-holder pins.
The critical distinction between single-ended and double-ended bypass wiring is a genuine shock-safety issue and must be understood before beginning any work.
In a single-ended bypass, one end of the tube receives line (hot) and neutral on its two pins, while the other end lamp-holders have their pins shorted together or left unconnected. The live mains voltage is present on only one end of the luminaire. The tube has an internal driver that works from the voltage delivered at a single end. This is the safer configuration for service personnel because a person handling the non-powered end of the tube cannot contact live pins.
In a double-ended bypass, line (hot) is wired to both pins of one lamp-holder (the two pins are shorted together at that end), and neutral is wired to both pins of the other lamp-holder. The full mains voltage therefore appears across the tube, with live at one end and neutral at the other. This means that a person who removes the tube and re-inserts it rotated 180 degrees will place live voltage on the end that appeared neutral before — creating a shock hazard if the fixture is not clearly labelled.
For both configurations, the ballast and starter (if present) must be physically removed or isolated. Wiring must be confirmed dead before any lamp-holder modification is made. The fixture must be permanently labelled to indicate that it has been converted to direct-wire LED operation.
These conversions must comply with applicable wiring standards including NEC/NFPA 70 (Article 410), BS 7671, AS/NZS 3000, and local authority requirements, and must use tubes that are labelled and certified for the specific bypass method.
How to wire led ballast bypass wiring diagram
- Isolate the circuit at the panel Switch off and lock out the circuit breaker feeding the luminaire. Use a calibrated non-contact voltage tester to verify that voltage is absent at the luminaire wiring before touching any conductors. Do not rely on the wall switch alone — it may interrupt only the neutral in some wiring configurations.
- Remove the tube and access the luminaire wiring Remove the existing fluorescent tube. Open the luminaire end-caps or wiring channel cover to access the ballast and lamp-holder wiring. Photograph the existing wiring before disconnecting anything.
- Disconnect and remove the ballast Disconnect all wires from the ballast terminals. Remove the ballast from the fixture chassis. Also remove the starter and starter socket if a magnetic ballast was fitted. Discard or recycle the ballast and any fluorescent lamps per local hazardous waste regulations.
- Identify the lamp-holder wiring — single-ended configuration For a single-ended bypass: connect the incoming line (hot) conductor and the neutral conductor to the two pins of the lamp-holder at one designated end of the fixture. At the other end lamp-holder, short the two pins together using a small wire bridge but do not connect them to any supply conductor. This end provides mechanical support only.
- Identify the lamp-holder wiring — double-ended configuration For a double-ended bypass: short the two pins of the line-end lamp-holder together and connect the incoming line (hot) conductor to both. Short the two pins of the neutral-end lamp-holder together and connect the neutral conductor to both. Clearly label the line end and neutral end permanently on the luminaire body.
- Verify insulation and lamp-holder integrity Confirm that all conductors are correctly terminated and no bare copper is exposed outside a terminal. Check that the lamp-holder bodies are undamaged and that pin-to-pin insulation resistance is acceptable. Ensure no conductors contact the metal chassis unless they are the intended earth conductor.
- Restore power, test the tube, and label the fixture Install the Type B LED tube in the correct orientation for the wiring configuration used. Restore circuit power and verify the tube lights. Apply a permanent label to the luminaire stating it has been converted to direct-wire LED operation and identifying which end carries line voltage.
Specifications
| Applicable tube base (T8) | G13 bi-pin, 26 mm diameter tube |
|---|---|
| Applicable tube base (T5) | G5 bi-pin, 16 mm diameter tube |
| Mains supply voltage (North America) | 120 V, 60 Hz |
| Mains supply voltage (UK / EU / AU) | 230 V, 50 Hz |
| Single-ended wiring: powered end | Line + neutral at one lamp-holder; other end shorted, no supply |
| Double-ended wiring: line end | Both pins shorted together, connected to line (hot) |
| Double-ended wiring: neutral end | Both pins shorted together, connected to neutral |
| Minimum lamp-holder voltage rating | 600 V (to ensure safe operation at mains voltage) |
Safety warnings
- All modifications to fixed luminaire wiring must comply with NEC/NFPA 70 Article 410 (USA), BS 7671 (UK), AS/NZS 3000 (Australia/NZ), or the applicable local standard. This work must be performed by a licensed or registered electrician in most jurisdictions. Obtain a permit where required.
- In a double-ended bypass, mains line voltage is present at the lamp-holder pins at one end of the fixture when the circuit is energised. Inserting a tube rotated 180 degrees from its intended position can expose personnel to live pins. The fixture must be permanently labelled with the line end clearly identified.
- Always isolate the circuit at the panel and verify dead with a calibrated voltage tester before touching any wiring. Do not rely on a wall switch as the sole means of isolation.
- Fluorescent lamps contain mercury. Dispose of removed fluorescent tubes according to local hazardous waste regulations. Do not break fluorescent tubes in an enclosed space.
- Only use LED tubes that are explicitly rated and certified for the bypass wiring method used (single-ended or double-ended). Inserting a Type A plug-and-play tube into a bypassed fixture will create a direct short circuit and may cause fire or explosion.
Tools needed
- Non-contact voltage tester
- Lockout/tagout device for circuit breaker
- Screwdrivers (flat and Phillips)
- Wire strippers
- Insulated crimp tool or push-in connector tool
- Multimeter
- Permanent marker or label maker
Common mistakes
- Leaving the ballast in circuit and wiring mains voltage to its output terminals — the ballast is not designed for this and will overheat or fail.
- Using a Type A (plug-and-play) tube in a bypassed fixture, creating a direct short circuit at the lamp-holders.
- Wiring both ends of the fixture with live voltage in a double-ended configuration and failing to label the line end, creating a shock hazard for future maintenance personnel.
- Failing to remove the starter in magnetic ballast fixtures, leaving it in circuit where it can cause intermittent faults.
- Not verifying that the lamp-holders are rated for direct mains connection — some older holders are rated only for the low voltage appearing at ballast output terminals.
Troubleshooting
- LED tube does not light after bypass conversion
- Cause: The tube is oriented incorrectly (for single-ended types the driver end must be inserted into the powered lamp-holder), or the supply is not reaching the lamp-holder pins due to a wiring error or open neutral. Fix: Verify with a non-contact tester that voltage is present at the powered lamp-holder pins. Check tube orientation marking. Confirm that both pins of the powered lamp-holder make reliable contact with the tube pins.
- Circuit breaker trips when tube is inserted
- Cause: A Type A plug-and-play tube has been inserted into a bypassed fixture, causing a short circuit, or the pin connections are bridging line to earth. Fix: Isolate the circuit immediately. Confirm the tube type — only Type B or Type A+B tubes should be used. Inspect lamp-holder wiring for conductor contact with the luminaire chassis.
- Tube flickers intermittently
- Cause: Poor contact between the tube pins and the lamp-holder, often caused by worn or spring-fatigued lamp-holder contacts after years of fluorescent tube use. Fix: Isolate the circuit. Replace the lamp-holders with new units rated for direct-wire mains connection. Confirm that the replacement lamp-holders' spring contacts are clean and making firm contact with the tube pins.
Frequently asked questions
What is the difference between single-ended and double-ended LED tube bypass wiring?
In single-ended bypass, line and neutral are both connected to pins at one end of the tube only; the other end lamp-holders are isolated or shorted but carry no mains voltage. In double-ended bypass, line is connected at one end and neutral at the other, so live voltage exists at both ends of the fixture. Single-ended is generally considered the safer installation from a service-handling perspective.
Can I leave the old ballast connected when installing a bypass LED tube?
No. A direct-wire (Type B) LED tube must have the ballast completely removed from the circuit. The ballast is not designed to pass mains voltage through to the lamp-holders without transformation. Leaving it in circuit will either prevent the LED tube from operating or create an overheating fault in the ballast.
Do I need to label the fixture after a bypass conversion?
Yes. Most installation guidelines and applicable codes require the luminaire to be permanently marked indicating it has been converted to direct-wire LED operation. This is essential for electricians or maintenance personnel who may later service the fixture, since inserting a fluorescent tube into a converted fixture will create a short circuit.
Are all LED tubes compatible with ballast bypass wiring?
No. Only Type B (direct-wire) and Type A+B (dual-mode) tubes are rated for ballast bypass. Type A (plug-and-play) tubes require a functioning compatible ballast and will not operate correctly, or may be damaged, if wired directly to mains. Always check the tube's labelling and installation instructions before wiring.
Is ballast bypass legal to do yourself?
In most jurisdictions, modifications to fixed luminaire wiring constitute electrical work that must be performed by a licensed or registered electrician. Even in places where homeowner electrical work is permitted, the modification must comply with the applicable wiring standard and may require inspection. The converted luminaire must also use a tube certified for the conversion method.
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