How to Install an Intermatic T103 Water Heater Timer

Mount the water heater timer to the wall near the water heater, using the supplied screws. Turn off the main circuit breaker in the service panel. Remove the screws for the panel cover and take the cover off.

Loosen the terminal screws on the circuit breaker that controls the water heater and remove the two wires. The two wires enter the service panel in a cable that also contains a ground wire. Follow the ground wire to the ground bus, loosen the terminal and remove the ground wire. Pull the cable out of the service panel.

Remove the sheathing from one end of the new three-wire cable with the stripper. Strip the insulation back 1/2 inch on each of the three wires. Insert the cable into the service panel through the same hole the old cable previously entered.

Insert the two colored wires under the circuit breaker terminal plates and tighten the screws. Insert the white wire into an empty terminal on the neutral bus — identified by the white wires that attach to it — and tighten the screw. Repeat for the bare ground wire on the ground bus. Replace the service panel cover and screws.

Remove the sheathing from the other end of the cable and strip the wire ends. Insert the cable into the strain relief on the timer box. Place the white wire under the "A" terminal plate and tighten the screw. Put the two colored wires under the plates on terminals "1" and "3" and tighten the screws.

Route the existing two-wire cable attached to the water heater to the timer and cut it off, leaving enough cable to enter at least 8 inches into the timer box. Remove the sheathing and strip the insulation from the wire ends. Insert the cable into the box through the strain relief and tighten the strain relief screws.

Put both bare ground wires — one from each sheathed cable — under the green terminal plate and tighten the screw. Place the ends of the two remaining wires under the terminal plates for the terminals labeled "2" and "4" and tighten the screws.

Position the "On" and "Off" trippers at the desired times for the water heater to turn on and off. Pull the dial out and rotate it to the current time. Turn the manual on/off lever located under the dial to on or off as required for the current time. Place the plastic insulating shield over the terminals. Close the timer door and turn on the main circuit breaker.