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How to Hook Up Series Start Capacitors for Single Phase Motors

The start capacitor on a single-phase motor shifts the voltage on the start winding to add a second phase of electrical current to the motor during start up. This gives the motor greater torque for starting heavy loads. As the motor starts and approaches full speed, a centrifugal switch disconnects the capacitor and start winding. Series capacitor wiring places the capacitor on one line leading from the power supply to the motor's start winding. Current travels through the capacitor and into the winding, then back to the power supply.

Things You'll Need

Screwdriver

Instructions

- 1
  Examine the new run capacitor case for indications that it is polarized. Capacitors with polarized terminals require that the positive terminal connects directly to the start winding and the negative terminal connects to the line supplying the current. Indications of polarity are a plus sign (+) or a negative sign (-) near the terminals.
- 2
  Look at the motor wiring schematic. This is usually inside the wiring box cover, or on a metal plate attached to the motor's case. Determine which leads from the motor connect to the run capacitor, and which of those two leads is the motor start winding lead. The leads usually have labels, such as T1, T2 and T3.
- 3
  Loosen the terminals on the capacitor with the screwdriver. Some capacitors may have a nut to loosen with a wrench.
- 4
  Place the lead from the motor start winding on a capacitor terminal. If the capacitor is polarized, place the start winding lead on the positive terminal. Place the other lead that attaches to the capacitor on the other capacitor terminal. Tighten the terminals with the screwdriver.

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