Select a location for mounting the timer near the water heater, and use the casing as a template for marking the mounting holes. Drill pilot holes, and secure the casing to the wall with screws.
Strip 1/2" of insulation from each wire in the casing. Connect the ground wire to the ground plug on the timer. Shape the bare wire ends so that each fits under the appropriate lug. Tighten the screws to secure the wires to the timer (pictured). Set the timer by inserting clips at the appropriate time markers. Turn the power back on.