Single-Ended LED Tube Wiring Diagram: 2026 Pinout Guide
A single-ended LED tube wiring diagram routes line voltage directly to one end of the fixture. Connect the hot wire (black) to one pin and the neutral wire (white) to the other pin on a non-shunted tombstone socket. The opposite socket remains unpowered as physical support, while the ground wire attaches to the metal chassis.
📌 Key Takeaways
- Power connects exclusively to one end using a non-shunted tombstone socket rated for 120V-277V AC input.
- Hot wire (black) and neutral wire (white) connect to separate pins on the single powered tombstone socket.
- The unpowered socket acts solely as a mechanical holder; never connect line voltage wires to both fixture ends.
- Connecting hot and neutral to opposite ends on a single-ended tube causes a direct short circuit that trips breakers.
- Always test tombstone continuity with a multimeter to verify non-shunted status before energizing the circuit.
Converting traditional fluorescent light fixtures to energy-efficient Type B direct-wire linear LED lamps requires a precise understanding of fixture circuit topology. A single-ended led tube wiring diagram provides the structural blueprint for delivering utility line voltage directly to one end of the lamp socket while isolating the opposite socket. Bypassing the legacy electronic or magnetic ballast removes a primary thermal failure point and eliminates parasitic electrical consumption. Executing this conversion accurately ensures strict adherence to National Electrical Code (NEC) standards, prevents hazardous phase-to-neutral short circuits, and maximizes system reliability across 120V to 277V commercial and industrial installations.
[ AC MAINS INPUT ]
120V - 277V AC, 50/60Hz SUPPLY
|
+-----------------------+-----------------------+
| | |
[ HOT WIRE ] [ NEUTRAL WIRE ] [ GROUND WIRE ]
(Black / Brown) (White / Gray) (Green / Bare)
| | |
v v v
+--------------+ +--------------+ +-----------------+
| Terminal 1 | | Terminal 2 | | Fixture Chassis |
| (Pin 1) | | (Pin 2) | | Ground Lug |
+--------------+ +--------------+ +-----------------+
| | |
+----------+ +----------+ |
| | |
v v v
+-----------------------+ ===================
| NON-SHUNTED SOCKET | FIXTURE GROUND BOND
| (Powered End Tombstone| ===================
+-----------------------+
| |
[ Pin 1 ] [ Pin 2 ] <--- (Internal Driver Input)
+-------------------------------------------------------+
| |
| SINGLE-ENDED POWERED LED TUBE |
| |
+-------------------------------------------------------+
[ Dummy ] [ Dummy ]
| |
+-----------------------+
| UNPOWERED SOCKET | <--- (Mechanical Support Only:
| (Isolated Tombstone) | No Electrical Connection)
+-----------------------+
Recommended Best Deal Products
Single-ended power (SEP) LED tubes require line voltage to be applied strictly to the two pins on the designated "powered" end cap. The internal LED driver bridges these two pins. The pins on the opposite end cap are electrically isolated (dummy pins) and serve exclusively for physical retention within the fixture. Consult our ballast bypass retrofit guide for supplementary structural modifications.
Single-Ended LED Tube Wiring Diagram Terminal and Wire Color Reference
When executing a direct-wire retrofit, maintaining accurate wire identification and proper pin assignment prevents damage to the LED tube driver and ensures compliant phase balancing. The standard NEC wire color code conventions apply, though voltage variations between 120V residential/commercial circuits and 277V industrial lighting grids dictate different conductor insulation colors.
| Wire Color Code | Circuit Function | Pin / Terminal Assignment | Electrical & Gauge Specifications |
|---|---|---|---|
| Black (120V/208V/240V) Brown (277V) |
Hot Wire (Line Phase) | Powered Tombstone Terminal 1 (Pin A) | 18 AWG solid copper THHN; carries full AC voltage to primary internal driver contact. |
| White (120V/208V/240V) Gray (277V) |
Neutral Wire (System Return) | Powered Tombstone Terminal 2 (Pin B) | 18 AWG solid copper THHN; completes circuit return path to service panel. |
| Green or Bare Copper | Ground Wire (Equipment Ground) | Metal Fixture Housing / Terminal Block Lug | 14 AWG / 12 AWG bonded to metal enclosure for fault current protection and EMI suppression. |
| Yellow / Blue / Red (Legacy) | Ballast Lead Wires | Disconnected / Extracted | Must be completely cut from ballast output sides and safely capped or removed entirely. |
In standard 120V–277V single-phase systems, line voltage is routed through an approved primary terminal block to distribute power evenly across multi-lamp fixtures. Ensure all branch circuit conductors entering the luminaire utilize solid or tin-coated stranded copper wire matching the temperature rating of the internal fixture wiring (minimum 105°C THHN insulation).
Non-Shunted Socket Architecture and Pin Assignment Rules
The single most critical mechanical requirement when reading a single-ended led tube wiring diagram is distinguishing between shunted and non-shunted G13 bi-pin tombstone sockets. Single-ended power lamps require non-shunted tombstones at the powered end cap. Failure to verify socket architecture prior to applying power will result in an immediate dead short across line and neutral conductors.
Understanding Non-Shunted vs. Shunted Tombstones
A non-shunted tombstone features two completely isolated internal contacts, providing individual push-in wire wire entry points for each pin of the G13 socket. This physical separation allows the hot wire to connect to Pin 1 and the neutral wire to connect to Pin 2 independently. Conversely, a shunted tombstone contains an internal copper busbar that permanently bridges both pin contacts together into a single electrical node. Instant-start electronic ballasts originally utilized shunted sockets to feed voltage to both lamp pins simultaneously through a single wire.
If line voltage (hot wire) and neutral wire are connected to separate terminals on a shunted socket, the internal busbar creates an immediate line-to-neutral dead short. When the breaker is energized, it will violently trip the breaker, melt tombstone plastic, and potentially damage the fixture or cause personal injury. Always perform a continuity test before applying power.
Multimeter Continuity Audit Procedure
To verify whether existing fixture sockets are non-shunted without dismantling the entire housing, perform a quick resistance audit using a Digital Multimeter (DMM):
- Isolate the lighting circuit by turning off the branch breaker and performing Lock-Out/Tag-Out (LOTO).
- Set your DMM to the Continuity or Resistance (Ω) setting.
- Place one DMM test probe into the left terminal slot of the G13 socket and the second probe into the right terminal slot of the same socket.
- If the DMM displays Infinite Resistance (O.L) and does not beep, the socket is non-shunted and safe for single-ended LED tube wiring.
- If the DMM displays 0.0 Ω and emits a continuous beep, the socket is shunted and must be replaced with an approved non-shunted G13 tombstone before proceeding.
How to Read and Execute the Single-Ended LED Tube Wiring Diagram
Executing a single-ended direct-wire retrofit requires systematically dismantling the legacy fluorescent circuit, removing the ballast, and landing line-voltage conductors directly on the primary socket contacts. Follow these sequential steps to perform the conversion safely and accurately.
Step 1: Circuit Isolation and Lock-Out/Tag-Out (LOTO)
De-energize the dedicated lighting branch circuit at the main distribution panel. Apply a lock-out/tag-out device to the circuit breaker switch. Use a calibrated non-contact voltage detector or AC voltmeter to test incoming conductors at the fixture terminal block, confirming zero potential between hot wire, neutral wire, and ground wire before touching internal components.
Step 2: Ballast Bypass and Complete Electrical Extraction
Remove the fixture diffuser/lens and strip away the central ballast wiring cover channel. Locate the electronic or magnetic ballast. Cut all incoming power supply wires (black hot wire and white neutral wire) close to the ballast casing to preserve wire length. Next, cut all outgoing ballast wire leads going to the tombstone sockets on both ends of the fixture. Remove the mounting screws holding the ballast to the chassis and extract the ballast unit entirely to reduce fixture weight and eliminate unwanted thermal mass.
Step 3: Powered End Tombstone Installation and Wire Landing
Select one end of the fixture to serve as the designated single-ended powered side. Inspect the G13 socket on this side to confirm it is non-shunted. Strip approximately 3/8 inch (10mm) of insulation off 18 AWG solid copper wire leads. Insert the line conductor (black or brown hot wire) into Terminal 1 of the push-in socket connector. Insert the system return conductor (white or gray neutral wire) into Terminal 2 of the same socket connector. For detailed socket mounting configurations, refer to our comprehensive shunted vs non-shunted tombstone guide.
Step 4: Mechanical Unpowered Socket Isolation
Move to the opposite end of the fixture housing. The socket at this end serves purely as a mechanical guide holder to anchor the unpowered dummy pins of the LED tube. Strip back any remnant wire leads attached to this socket and cap them with individual wire nuts, or remove the wire leads entirely from the push-in slots. Do not connect any hot, neutral, or ground wire conductors to the unpowered tombstone socket.
Step 5: Chassis Ground Wire Bonding and Relabeling Compliance
Ensure the incoming system ground wire (green or bare copper wire) is securely attached to the structural metal frame of the fixture using a dedicated green grounding screw or star washer lug. Per UL 1598C standards, permanently adhere the high-voltage retrofit field-applied warning label to the ballast channel cover where it is clearly visible during future maintenance. Reinstall the wire tray cover and insert the single-ended LED tube, making sure the end marked "Input Power" or "AC Line" aligns precisely with the powered non-shunted socket.
Underwriters Laboratories standard UL 1598C mandates that any luminaire modified via ballast bypass must feature an indelible safety label stating: "Notice: This luminaire has been modified and can no longer operate fluorescent lamps. Use only Type B Direct-Wire LED tubes." This prevents accidental installation of standard fluorescent tubes, which would rupture instantly if subjected to line voltage.
Wire Gauge, Operating Voltage, and Ballast Bypass Specifications
When engineering linear LED conversions across high-density commercial fixtures, wire gauge sizing, voltage drop mitigation, and terminal connection parameters must comply with rigorous electrical engineering specifications. Below are the standard operating boundaries for Type B direct-wire LED tube retrofits.
Conductor Gauge and Current Capacity
Internal fixture wiring typically utilizes 18 AWG solid THHN/T90 copper wire rated for 600V and 105°C. Because LED T8 tubes draw significantly less current than legacy T12 magnetic systems (typically 0.12A to 0.15A at 120V per 18W tube, compared to 0.45A for fluorescent), 18 AWG solid conductor wire easily handles multi-lamp parallel array loads without thermal stress. When feeding primary terminal blocks, supply branch conductors must be sized according to circuit breaker ampacity (14 AWG for 15A circuits, 12 AWG for 20A circuits).
Universal Line Voltage Compatibility
Most modern single-ended LED tubes incorporate internal constant-current drivers designed for universal AC voltage input (120V to 277V AC at 50/60Hz). This wide input range accommodates standard residential 120V circuits, 208V/240V multi-phase industrial circuits, and 277V commercial overhead lighting grids without requiring step-down transformers or external drivers. Check the specific voltage stamp on the tube housing prior to energizing line voltage.
Terminal Block and Splicing Requirements
When converting multi-lamp fixtures (3-lamp or 4-lamp troffers), do not stack multiple solid 18 AWG conductors into a single tombstone push-in port. Instead, use an approved multi-pole lever-nut terminal block or wire nut junction point. Run a master hot wire and neutral wire to the terminal block, then branch out individual 18 AWG feed conductors to each powered tombstone socket. This guarantees even wire clamping force, prevents loose mechanical connections, and eliminates arcing risks.
Common Single-Ended LED Tube Wiring Diagram Faults and Diagnostic Fixes
Incorrect wiring configurations during ballast bypass installations can trigger instantaneous short circuits, nuisance breaker trips, severe radio frequency (RF) interference, or localized lamp failure. Inspect the following failure modes to diagnose installation faults quickly.
Fault 1: Direct Line-to-Neutral Short Circuit Across a Shunted Socket
- Symptom: Branch breaker trips instantly upon powering the circuit; loud arc pop at the tombstone.
- Root Cause: Hot wire and neutral wire were connected to opposite sides of a shunted socket. The internal shunt bridged line phase directly to ground return.
- Corrective Action: Disconnect power, replace the damaged shunted tombstone with a verified non-shunted G13 tombstone, replace blown fuses or reset breaker, and verify zero continuity between socket terminals before re-energizing.
Fault 2: Reverse Installation of Single-Ended Lamp Pins
- Symptom: The LED tube fails to illuminate, but no breaker trip occurs.
- Root Cause: The tube was installed backwards, placing the unpowered dummy pin end into the powered non-shunted socket, and the internal driver pins into the isolated dummy socket.
- Corrective Action: Remove the tube, rotate it end-for-end 180 degrees so that the end cap marked "AC Input" or "L/N" snaps firmly into the powered tombstone socket.
Fault 3: RF/EMI Interference and High-Voltage Capacitive Hum
- Symptom: Commercial wireless sensors, radios, or access points experience noise interference when lights are turned on.
- Root Cause: Missing ground wire bond on metal fixture chassis or ungrounded LED driver internal ground trace.
- Corrective Action: Verify that the green equipment grounding conductor is mechanically bonded directly to the bare metal chassis frame with less than 0.1 Ω of earth ground resistance. Ensure excess ballast bypass wiring leads are trimmed and not forming inductive wire loops inside the channel.
Fault 4: Thermal Melting of Tombstone Push-In Contacts
- Symptom: Scorching or discoloration on the plastic tombstone body near wire entry points; intermittent flickering.
- Root Cause: Reusing old, brittle G13 tombstones whose internal leaf springs lost tension, creating a high-resistance contact point under continuous load.
- Corrective Action: Strip away compromised sockets and replace them with brand-new, flame-retardant polycarbonate non-shunted tombstones featuring stainless steel leaf spring push-in connectors.
Single-Ended LED Tube Wiring Diagram Technical Questions Answered
Can You Wire a Single-Ended LED Tube to a Shunted Socket?
No, you cannot wire a single-ended LED tube directly to a shunted socket if line and neutral wires land on that same socket. A shunted socket connects its two internal contacts together, which will produce a short circuit between hot and neutral conductors. However, if you utilize a special external terminal block wiring configuration—or if you convert the fixture using double-ended power LED tubes instead—shunted sockets may be used. For single-ended power (SEP) tubes, always install non-shunted tombstones on the powered end.
Does it Matter Which Pin Connects to Hot and Neutral on a Non-Shunted Socket?
In standard non-polarized AC circuits operating single-ended LED tubes, internal bridge rectifiers inside the lamp driver automatically rectify incoming AC voltage to smooth DC power. Therefore, swapping the hot wire and neutral wire positions on Pin 1 and Pin 2 of a non-shunted powered socket will not damage the lamp or affect performance. However, maintaining consistent wire color code positioning (Black to Pin 1, White to Pin 2) across all fixtures is recommended for organized troubleshooting and circuit tracing.
What Happens if Line Voltage is Connected to Both Ends of a Single-Ended LED Tube?
If line voltage (hot wire on one end, neutral wire on the opposite end) is applied to a single-ended LED tube, the lamp will not illuminate, and internal driver damage or blown fuse protection may occur. Connecting power across opposite ends is the wiring scheme reserved exclusively for Double-Ended Power (DEP) LED tubes. Always check the model number and wiring schematic printed on the tube housing to verify whether the lamp is single-ended or double-ended prior to applying voltage.
How Many Single-Ended LED Tubes Can Be Wired in Parallel on One Circuit?
The maximum number of single-ended LED tubes that can be safely connected in parallel on a single lighting branch circuit depends on the total wattage load and breaker rating. Under NEC regulations, continuous lighting loads must not exceed 80% of total circuit breaker capacity. On a standard 120V, 20-amp branch circuit (2,400W total capacity), the maximum continuous load is 1,920 watts. If using standard 15-watt LED T8 tubes, you can safely wire up to 128 lamps in parallel on a single breaker line.
Safety Protocols and Final Circuit Inspection for Single-Ended LED Retrofits
Prior to re-energizing the main power supply and closing out the luminaire installation, perform a comprehensive visual and electrical safety audit. Systematically checking mechanical connections, socket integrity, and ground continuity prevents unexpected field failures and ensures long-term operational performance in industrial facilities.
Begin by verifying that all non-shunted tombstones are firmly locked into the metal fixture chassis keyholes. Wobbly or loose tombstones cause pin misalignment, leading to arcing and premature mechanical fatigue. Ensure that no stray wire strands extend past push-in housing ports, and verify that 18 AWG solid copper conductors are seated past the internal spring-retainer depth (minimum 3/8-inch strip length). Check our complete commercial 277V lighting circuits guide for advanced panel distribution layout strategies.
Confirm that the equipment ground wire is fastened tightly against clean, unpainted bare metal on the fixture chassis, achieving an earth bonding resistance reading below 0.1 ohms on your multimeter. Inspect the wire routing pathway inside the wiring channel cover to ensure conductors are clipped away from sharp metal edges, preventing long-term vibration chafing or insulation breakdown. Once mechanical checkouts are complete, install the single-ended LED tube with the powered end cap correctly engaged in the non-shunted socket, replace the diffuser lens, remove lock-out/tag-out devices from the distribution panel, and re-energize the circuit.
Step-by-Step Guide to Understanding the Single-Ended Led Tube Wiring Diagram
Identify - Turn off main electrical power at the breaker panel and verify the circuit is dead using a non-contact voltage tester.
Locate - Remove existing fluorescent lamps, open the fixture ballast cover, and disconnect all wires connected to the old electronic or magnetic ballast.
Reference - Inspect the single-ended led tube wiring diagram and tombstone sockets to confirm non-shunted pin assignments on the powered end.
Connect/Route - Route the black hot wire and white neutral wire directly to separate terminals on the non-shunted tombstone socket, and secure the green ground wire to the chassis.
Verify - Insert the LED tube, ensuring the input end with pin markings aligns with the powered tombstone socket, then restore power to test operation.
Troubleshoot - If the tube flickers or fails to light, re-check wire color code alignment, ensure sockets are non-shunted, and verify supply AC voltage.
