Intermatic 104R Install Instructions

The Intermatic T104R is a 24-hour mechanical time switch for loads up to 40 amps.


An outdoor timer can be installed with basic tools.An outdoor timer can be installed with basic tools.
It comes factory-configured for 240-volt operation and is most commonly used for swimming pool filters and water heaters. The "R" suffix denotes a rain-tight case. The T104R allows up to 12 on/off operations each day. Installation requires connecting the timer to a 240-volt line and attaching the supply wires to the appropriate load --- the pump, heater or other device the timer is powering.

Strip 1/2 inch of insulation from the ends of the power wires (red, black and green) from the breaker panel to the timer, and from the three wires supplying the load.

Route the wires from the breaker panel and the load through two punchout access holes in the bottom of the timer's case.

Lift up the insulator cover inside the timer case to expose the wire terminals. The terminals are labeled in this sequence: "A" (unused in 240v application), "1" (black hot wire from breaker box), "2" (black hot wire to load), "3" (red hot wire to breaker box) and "4" (red hot wire to load.)

Referring to the terminal assignments, connect each wire to its appropriate terminal by inserting the bare wire end under the terminal pressure plate and tightening with a screwdriver. The green ground wires from the breaker box and the load both attach and are bonded together at the single ground screw terminal in the bottom of the case, below the terminal strip.

Swing insulator cover down into position, covering all terminal connections.


Turn on the power at the breaker box. Set the on and off times by placing supplied trippers on the clock dial at desired times and tightening screws firmly to affix them to the clock dial.

Set the current time on the clock by pulling the clock dial outward and turning to align the current time with the time pointer on the dial.

Move the timer operation lever at the bottom of the clock from the "Timer" position to the "Manual" position to override the timer and operate in manual mode, if necessary.

Things You Will Need

  • Three-conductor solid or stranded copper wire. Wire size may range from 14 AWG to 8 AWG to accommodate loads ranging from 10 amps up to 40 amps respectively. (Recommended AWGs are printed inside the timer case.)
  • Wire cutters
  • Wire strippers
  • Screwdriver


  • Make sure the power supply is turned off before beginning this procedure.

About the Author

Gus Stephens has written about aviation, automotive and home technology for 15 years. His articles have appeared in major print outlets such as "Popular Mechanics" and "Invention & Technology." Along the way, Gus earned a Bachelor of Arts in communications. If it flies, drives or just sits on your desk and blinks, he's probably fixed it.