1. Introduction
The Leviton DT104-1LW Countdown Timer Switch is designed to automate the operation of household lights, heaters, and exhaust fans. This single-pole switch offers preset time options of 30 minutes, 1 hour, 2 hours, and 4 hours, along with a manual off button. It is engineered for easy installation, fitting into standard wall boxes and accommodating various wiring configurations, including those without a neutral wire. The timer helps conserve energy by ensuring connected devices automatically turn off after a set duration.
2. Important Safety Information
WARNING: To avoid fire, shock, or death; turn off power at circuit breaker or fuse and test that power is off before wiring!
- This product must be installed in accordance with all national and local electrical codes.
- Installation should be performed by a qualified electrician if you are unsure about the process.
- Ensure the power supply is disconnected before attempting any installation or maintenance.
- Do not use this device to control lights if it is the only light source in the area, as it will turn off automatically.
- A ground wire is required for installation.
3. Package Contents
- One DT104-1LW Leviton Decora 15 Amp, 4-Hour Countdown Timer Switch (White)
4. Product Specifications
| Model Number | DT104-1LW |
| Operation Mode | Manual |
| Current Rating | 15 Amps |
| Operating Voltage | 120 Volts |
| Contact Type | Normally Open |
| Circuit Type | Single Pole |
| Wattage | 1800 watts (Incandescent/Halogen), 600W (LED/CFL) |
| Fan/Motor Rating | 1/2 HP / 9.8 Amps |
| Dimensions (L x W x H) | 4.13 x 1.73 x 1.34 inches |
| Color | White |
| Timer Options | 30 minutes, 1 hour, 2 hours, 4 hours |
Note: Specifications are subject to change without notice.
5. Installation Instructions
5.1 Pre-Installation Checklist
- Ensure power is OFF at the circuit breaker.
- Verify that your existing switch is a single-pole switch (controls a load from one location).
- Confirm that a ground wire is available in your wall box.
- The timer switch is designed for a shallow fit in the wall box.
5.2 Wiring the Timer Switch
The DT104-1LW features interchangeable line and load wires to simplify installation and a Green Flex Sleeve for versatile grounding options.
- Turn Off Power: Locate the circuit breaker or fuse that supplies power to the switch you are replacing and turn it OFF. Test the circuit with a voltage tester to ensure no power is present.
- Remove Existing Switch: Carefully remove the wall plate and unscrew the existing switch from the wall box. Disconnect the wires from the old switch.
- Identify Wires: You will typically find two black wires (line and load), a green or bare copper ground wire, and potentially a white neutral wire.
- Connect Ground Wire: Connect the green or bare copper ground wire from the wall box to the green wire on the DT104-1LW timer switch.
- Connect Line/Load Wires: The DT104-1LW has two black wires for line and load connections. These are interchangeable. Connect one black wire from the timer to the line wire from the wall box and the other black wire from the timer to the load wire from the wall box.
- Neutral Wire (Optional):
- If no neutral wire is available: The Green Flex Sleeve on the timer's white wire should remain intact. Connect the white wire (with the green sleeve) to the ground wire bundle in the wall box. This allows the device to function without a dedicated neutral wire.
- If a neutral wire is available: Remove the Green Flex Sleeve from the white wire of the timer. Connect this white wire to the neutral wire bundle in the wall box.
- Secure the Switch: Carefully push the wired switch into the wall box. Secure it with the provided screws.
- Install Wall Plate: Attach a compatible Decora wall plate (sold separately) over the switch.
- Restore Power: Turn the power back ON at the circuit breaker.

Figure 1: The Leviton DT104-1LW switch provides a modern upgrade from traditional toggle switches.

Figure 2: Wiring diagram for the DT104-1LW, highlighting interchangeable line/load wires and the Green Flex Sleeve for neutral or ground connection.

Figure 3: Detailed view of the DT104-1LW's rear, showing wiring terminals and the Green Flex Sleeve.
6. Operating Instructions
The DT104-1LW features five buttons for easy operation:

Figure 4: Timer buttons on the DT104-1LW switch.
6.1 Setting the Timer
- Press the desired time button (4H, 2H, 1H, or 30M) to activate the connected load for that duration.
- The corresponding LED indicator next to the button will illuminate to show the active timer setting.
- The load will automatically turn off once the selected time expires.
6.2 Manual Off
- To turn off the connected load before the timer expires, press the bottom-most button (Off button).
6.3 Timer Override (Constant ON)
To keep the connected load ON indefinitely (or for 24 hours, depending on model specifics), you can override the timer function:
- Press and hold the topmost button (4H) for several seconds until its LED indicator blinks. The load will remain ON.
- To exit override mode, press any timer button or the Off button.

Figure 5: Activating the timer override function.
6.4 Locator LED
The bottom-most button features a Locator LED that illuminates when the switch is OFF, making it easy to locate in the dark.

Figure 6: LED indicators and Locator LED on the DT104-1LW switch.
7. Maintenance
7.1 Cleaning
To clean the timer switch, gently wipe the surface with a soft, damp cloth. Do not use abrasive cleaners or solvents, as these may damage the finish.
7.2 Changing Faceplate Color
The DT104-1LW is designed with a removable faceplate, allowing for easy color changes using DTKIT faceplates (sold separately). These are available in white, ivory, light almond, gray, black, and brown to match various interior designs.

Figure 7: Instructions for changing the faceplate color.

Figure 8: Available DTKIT faceplate colors.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Timer does not turn ON/OFF. | No power to the switch. Incorrect wiring. | Check circuit breaker. Verify wiring connections (line, load, ground, neutral if used). Ensure power is OFF before checking wiring. |
| Load remains ON indefinitely. | Timer override mode is active. | Press any timer button or the Off button to exit override mode. |
| Locator LED is not lit when OFF. | No power to the switch. LED malfunction. | Check power supply. If power is present and other functions work, the LED may be faulty. |
| Switch does not fit in wall box. | Wall box is too shallow or crowded with wires. | Ensure wires are neatly folded. If necessary, consider a deeper wall box (professional installation recommended). |
9. Warranty and Support
For warranty information, technical support, or to purchase replacement parts and accessories, please visit the official Leviton website or contact Leviton customer service. Keep your purchase receipt as proof of purchase.
Leviton Website: www.leviton.com





