How to Discharge a Capacitor
A capacitor stores an electrical charge. When
used with a motor the capacitor releases its stored charge in
a surge in order to start the motor turning. In this role, it
is referred to as a start capacitor.
Please read our safety
information before attempting any testing or repairs.
A capacitor can be extremely dangerous.
It can hold a lethal charge indefinitely even when not connected
to a power source. Never touch the terminals of a capacitor until
you have discharged it.
Because of its ability to store energy, it is
dangerous even when disconnected from a power source. In order
to handle it safely, it must first be discharged.
While it can be discharged by simply shorting
the terminals together, this is dangerous to you and can cause
electrical arc damage to tools and to the capacitor.
To safely discharge a capacitor used on a refrigerator's motor, you will need
a 20,000 ohm wire wound resistor rated for 2 watts or more, two screwdrivers
and two jumper wires with alligator clips on each end of each
wire. First clamp one clip to one wire of the resistor. Connect
a clip from the other wire to the other wire on the resistor.
Take the clip on the other end of either wire and connect it to
a screwdriver. Take the remaining free clip and clip it to another
screwdriver. While holding the insulated handles of the screwdrivers,
touch one screwdriver to each terminal on the capacitor. After a few seconds the capacitor
should be discharged. Do not hold the capacitor during this process because it can become hot as it dissipates the capacitor's energy.
After following the steps above, for an added
margin of safety, hold a screwdriver by the insulated handle.
Touch the blade of the screwdriver simultaneously to both terminals
of the capacitor to make certain it has been discharged.