Electrical switches usually last a long time, but they do
wear out, or fail. Replacing a household switch is not hard, in most cases. Of
course there are some very important safety precautions to observe, primarily,
make sure the power to the switch has been turned off before attempting any
repairs. Find the circuit breaker, or fuse for older systems, that controls the
power to the faulty switch and turn it off. If it is a fuse, remove it.
Removing a switch:
Once you are absolutely certain the power to the switch is
off, unscrew the face plate that surrounds the switch and remove it. You will
find another pair of screws underneath the faceplate, usually one at the top of
the switch and one at the bottom. When you remove these screws the switch will
be free for you to pull out of the wall. There are some wires attached to the
side(s) switch. These are held on by either a screw or, less often, by a spring
clamp.
The switch may have both side terminals and holes in the
back for what is called back-wiring. In back-wiring the wires are connected to
the back of the switch, rather than the side(s). Regardless of whether the
wires attach to the side or the back, the attachment point is called a
terminal. Use a test light, available at most hardware stores, to make sure
there is no electricity flowing through the wires to the terminals. Touch the
test light's probes to each terminal. If the tester lights up, stop immediately
and go and find the correct circuit breaker and turn it off, or remove the
correct fuse. Then test again.
If the test light does not light up, you may assume it is
safe to proceed. To remove the switch entirely you must loosen the terminal
screws holding the wires and carefully pull the wires off. It is best to do
this one terminal at a time and not allow the bare ends of the wires touch each
other.
Testing a switch:
Continuity testers are available at most hardware stores.
They are inexpensive and provide a safe means of testing switch to determine if
it is in working order. With the switch removed from the wires, use the
continuity tester to see if there is continuity through the switch. Do this by
touching the probes of the tester to the terminals with the switch in the ON
position. Power should flow between the top and bottom terminal. If the tester
doesn't light up, the switch is defective. Don't throw it away though; take it
to the hardware store to make sure you get the correct type of switch as a
replacement because, as you will see below, the variety of types of switches
can be confusing.
Types of switches:
There are three types of household switches. A switch that
has only two terminals is called a single-pole switch. It alone controls the
circuit. Then there is a three-way switch. This one has three terminals and one
is marked COM, or common. This is the terminal that the "hot" wire
attaches to and the other two terminals are switch leads. The three-way switch
is used to control a circuit from two different locations, like the top and
bottom of a stairwell for example. A double-pole switch has four terminals and
is normally used to control higher voltage appliances. This type of switch can
be identified by the ON/Off markings on it. A four-way switch also has four
terminals, but no ON/OFF markings. The four-way switch is used along with two
three-way switches to control one outlet, or fixture, from three separate
locations. Most switches, no matter what type, will also have a green terminal,
and this is for the green ground wire.
Installing a new switch:
This is where it gets easier. All you do is reverse the
procedure you followed to remove the switch. Loop the bare end of each wire
tightly around the proper terminal screw using a pair of needle nose pliers.
Loop it in a clockwise direction so that when the screw is tightened it will
draw the wire tight to the terminal. After the wires are all reconnected,
making sure no bare wires touch each other; gently push the switch back into
the wall. Put the screws back in and then put the faceplate on and you're done.
Turn the circuit breaker back on and test the switch.
Note: Finetuning is not responsible for any injury or damage
caused by readers following the above advice.