Things You'll Need
10-gauge wire whip
Two conduit nuts
Most pool pumps use a 220-volt capacitor-start induction-run (CSI) electric motor wired directly to a pool timer through a flexible conduit, or whip. The pool timer acts like an automated switch. Many pool pump motors use a thermal overload protector that prevents the motor's windings from overheating. Overheated windings will cause premature motor failure. Unlike 110- volt motors, which use one 110-volt hot wire and one neutral wire, 220-volt motors use two 110-volt wires.
Turn the electricity to the pool pump timer off at its circuit breaker. Follow the wires from the pool timer to the circuit breaker box. The correct circuit breaker will have a "Pool" label. Turn the correct circuit breaker to the "Off" position.
Feed a 10-gauge wire whip into the pool timer though the hole on the bottom of the pool timer's housing. A 10-gauge wire whip, a flexible conduit with three insulated 10-gauge wires inside, has weather-proof conduit connectors on each side.
Slide a conduit nut over the whip's wires, inside of the pool timer, and onto the whip's conduit connector. Finger tighten the nut then tap on the nut's ears with a flat-head screwdriver to seat it against the pool timer's housing. A conduit nut has small ears around its edge.
Strip 1/2 inch from each 10-gauge wire coming from the whip with wire strippers. Each wire will have different colored insulation: black, green and white.
Push the whip's wires to the pool timer's wire terminals and tighten the terminal's locking screws with a flat-head screwdriver. Place the black wire in the terminal labeled "L1" and the white wire in the terminal labeled "L2." Connect the green insulated wire to the ground terminal. The ground terminal usually mounts to the pool timer's housing and will have a green wire, from the timer, and a bare copper wire, from the circuit breaker box, connected to it.
Remove the pool-pump motor's electrical cover with a nut driver. The motor's cover usually uses 1/4- or 5/16-inch hex-head screws to hold the cover in place. After removing the screws the cover will slide off of the rear of the motor.
Push the other end of the 10-gauge whip into the pool pump's motor through the hole near the bottom of the motor's housing. Feed the wires to the motor's electrical terminals.
Slide a conduit nut over the wires in the motor and finger tighten the nut on the whip's conduit connector. Seat the nut against the motor's housing with a flat-head screwdriver.
Strip 1/2 inch from each 10-gauge wire in the pool pump's motor with wire strippers.
Push the 10-gauge wires into the motor's wire terminals and tighten the terminal's locking screws with a flat-head screwdriver. Push the black insulated wire into the terminal marked "L1" and the white wire into the terminal marked "L2." Push the green wire into the ground terminal located on the motor's housing.
Replace the pool-pump motor's housing and tighten its screws with a nut driver.
Flip the pool's circuit breaker to the "On" position.
Never rely on the pool timer's switch to cut the power to the pool pump. The pool timer will continue to run as long as the circuit breaker remains in the "On" position and can turn on unexpectedly.