1. Introduction
The Intermatic T104P3 Mechanical Time Switch is designed for precise 24-hour control of various electrical loads in industrial, commercial, and residential settings. This robust device features a double pole, single throw configuration and is housed in a durable NEMA 3R enclosure, making it suitable for both indoor and outdoor installations. It supports up to 12 ON/OFF operations per day with a minimum on/off time of one hour, and includes an override switch for manual control. This manual provides essential information for the safe installation, operation, and maintenance of your T104P3 time switch.
2. Safety Information
WARNING: Risk of Electrical Shock.
- Always turn power OFF at the main panel before servicing this switch or the equipment it controls.
- Use copper conductors only.
- Reinstall the safety guard after wiring.
- Installation should be performed by a qualified electrician in accordance with all local and national electrical codes.
- Ensure the enclosure is properly sealed after installation to maintain its NEMA 3R rating.
3. Package Contents
Verify that all components are present upon unpacking:
- Intermatic T104P3 Mechanical Time Switch with NEMA 3R Enclosure
- One (1) ON Tripper
- One (1) OFF Tripper
- Instruction Manual (this document)
4. Specifications
| Model Number | T104P3 |
| Voltage | 208-277 VAC, 60 Hz |
| Configuration | Double Pole, Single Throw (DPST) |
| Enclosure | NEMA 3R Plastic (Beige) |
| Maximum Load Rating | Up to 40 Amps per pole |
| Minimum ON/OFF Time | 1 Hour |
| Daily Operations | Up to 12 ON/OFF operations |
| Dimensions (D x W x H) | 6.5" x 10" x 4" |
| Item Weight | 2 Pounds |
Certifications:

Image: CSA, UL, and LED compatibility logos indicating product compliance with safety and performance standards.
5. Setup and Installation
Important: Ensure power is disconnected at the circuit breaker before beginning any installation work. This device must be installed by a qualified professional.
- Mounting the Enclosure: Select a suitable location for the time switch, ensuring it is accessible for programming and maintenance. The NEMA 3R enclosure is weather-resistant, allowing for outdoor installation. Securely mount the enclosure to a flat surface using appropriate hardware.
- Wiring: Open the enclosure door. Carefully remove the safety guard to access the wiring terminals. Connect the electrical supply wires and load wires to the designated terminals as per the wiring diagram provided inside the enclosure. Ensure all connections are tight and secure. This unit requires copper conductors only.

Image: The Intermatic T104P3 Mechanical Time Switch with its NEMA 3R enclosure open, revealing the internal mechanical dial and the wiring terminal block with a safety warning.
- Reinstall Safety Guard: Once wiring is complete, replace the safety guard over the terminals.
- Close Enclosure: Close and latch the enclosure door to maintain its weather-resistant rating.
- Restore Power: Restore power at the main circuit breaker.
6. Operating Instructions
The T104P3 time switch allows for easy programming of ON/OFF cycles.

Image: A detailed view of the mechanical timer dial, showing the 24-hour markings, the current time indicator, and the slots for inserting ON and OFF trippers.
- Set Current Time: Rotate the dial clockwise until the current time aligns with the time indicator arrow. The dial is marked for 24 hours.
- Install Trippers: Insert the ON tripper (typically green or silver) into the dial at the desired time for the load to turn ON. Insert the OFF tripper (typically red or black) at the desired time for the load to turn OFF. Ensure trippers are securely seated. The minimum ON/OFF duration is one hour. You can install up to 12 pairs of ON/OFF trippers for multiple cycles per day.
- Manual Override: The time switch includes a manual override lever (often red or orange) located below the dial. This lever allows you to temporarily switch the load ON or OFF without affecting the programmed schedule. Move the lever to the 'ON' or 'OFF' position as needed. The timer will resume its programmed schedule at the next scheduled ON or OFF event.
7. Maintenance
The Intermatic T104P3 is designed for durability and requires minimal maintenance.
- Cleaning: Periodically clean the exterior of the enclosure with a damp cloth. Do not use abrasive cleaners or solvents. Ensure the enclosure door seal is free of debris.
- Inspection: Annually inspect the wiring connections for tightness and signs of corrosion. Check the enclosure for any damage that might compromise its weather resistance.
- Tripper Check: Ensure trippers are securely in place and have not shifted over time.
Always disconnect power before performing any internal inspection or cleaning.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Load does not turn ON/OFF at programmed times. |
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| Timer dial is not rotating. |
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| Load does not receive power, even with timer set correctly. |
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9. Warranty and Support
For warranty information and technical support, please refer to the documentation included with your product packaging or visit the official Intermatic website. You may also contact Intermatic customer service directly for assistance with product inquiries, troubleshooting, or replacement parts.
Intermatic Contact Information: Please refer to www.intermatic.com for the most current contact details.





