Applies To

Intermatic ST01 and EI600 Series 7-Day Programmable Timers

Question / Problem

How do I wire my ST01 or EI600 timer?

Safety Warning

Common Installation / Application Conditions

• Installed in a single-pole or three way wall switch box.
• Three-way installations: The timer must be installed in the line side box (the first switch in the circuit), not the load side box. If the timer is installed in the load side box, it will not operate correctly.
• Used to control lighting or other switch-controlled loads within the timer rating.
• Uses a CR2 lithium battery to power the display (neutral wire is not required).

Step-by-Step Resolution

1. Turn off power at the breaker

   Shut off power to the circuit at the electrical panel. Verify that power is off using a voltage tester.

2. Remove the existing wall switch

   Remove the wall plate, then unscrew and gently pull the existing switch out of the wall box without disconnecting the wires yet.

3. Identify the circuit wires

   Use a voltage tester to identify the line (hot) conductor before disconnecting any wires. In three-way applications, also identify the load conductor and both traveler conductors.

4. Disconnect and label the wires

   Turn the breaker off again if it was turned on during testing. Disconnect the wires from the existing switch and label them as line, load, and travelers to avoid confusion.

5. Wire the timer for single-pole operation
   • Connect the timer black wire to the line (hot) conductor.
   • Connect the timer blue wire to the load conductor going to the light or other load.
   • Cap the timer red wire; it is not used in single-pole applications.
   • Connect the timer green wire to the equipment grounding conductor in the wall box.

6. Wire the timer for three-way operation (line-side box only)

   Install the timer only in the line-side wall box. The timer will not operate correctly if installed in the load-side box. In three-way circuits, the timer uses one conductor as the load feed and another as a control traveler to the remote three-way switch.

   • Connect the timer black wire to the line (hot) conductor in the line-side box.
   • Connect the timer blue wire to the conductor that feeds the load. In some circuits this may be a conductor that continues to the other three-way box and then to the load, as shown in the wiring diagram.
   • Connect the timer red wire to the remaining traveler conductor that runs to the remote three-way switch.
   • Connect the timer green wire to the equipment grounding conductor in the wall box.
   • At the remote three-way switch, install the supplied jumper wire between the common terminal and the traveler terminal that corresponds to the timer blue wire conductor, following the wiring diagram.

   Because three-way wiring layouts vary, always follow the official ST01 / EI600 wiring diagram for your specific circuit configuration.

7. Install the CR2 battery

   Insert the CR2 lithium battery into the timer to power the display and internal clock. Confirm that it is fully seated.

8. Mount the timer in the wall box

   Carefully fold the wires into the wall box, position the timer, and secure it with the mounting screws. Reinstall the wall plate.

9. Restore power and verify operation

   Turn the breaker back on. Confirm that the connected load can be controlled by the timer.

Tips / Additional Notes

• Always use a voltage tester to verify which conductor is line (hot) before disconnecting the existing switch.
• Labeling conductors during removal helps prevent wiring errors, especially in three-way circuits.
• The ST01 and EI600 do not wire the same way as a traditional 3-way toggle switch. In three-way applications, one conductor becomes the load feed and the other is used as a control traveler.
• The timer must be installed in the line-side box for three way applications. Installing the timer in the load-side box will prevent proper operation.
• If the display does not power on after wiring, recheck the CR2 battery installation and confirm that power has been restored at the breaker.
• When in doubt about conductor identification, refer to the official ST01 / EI600 wiring diagram and consult a qualified electrician.

Visual Diagram