This is a switch in a bathroom that turns on a light on the ceiling
and also a fan (actually, the fan is separate from the light and has a
plug that goes into a receptacle next to the fan--1960 squirrel cage
type). So the single switch actualy controls the light and an outlet
for the fan.
For a long time there was an intermittent problem where when you
flipped the switch, it would make a popping sound. I recently had the
switch replaced and asked the electrician if there was any sign of
wires damaged or burned. He said no and replaced the switch.
Well, it is not as loud as it had been at it's worse, but I can still
occassionally hear a slight pop when turning it on. Any ideas on what
would cause this type of thing?
When the contacts in the switch touch, the load of the lights and motor
cause an arc inside the switch which can sometimes be audible. You might
want to replace it with a heavier or better grade of switch
Every time you get that pop, it's burning away a little more of the contacts
inside the switch. At some point it'll stop working properly and need to be
replaced. A better grade of switch, like spec grade, or a heavier rated
switch such as a 20 amp, will have more substantial contacts, and will make
a more positive connection, so it will be less likely to make a pop, and
will last longer
I can hear the sirens of the fire truck rushing to your house right
now. You need a qualified electrician. Call one NOW. This is an
EMERGENCY. Or shut off the power to your entire house until one
arrives. You might see flames shooting out of that switch any minute.
Kill the power NOW.
As long as you need to repair this situation, I suggest you install a
separate fan switch, preferably a timer or humidistat style.
Right now when you leave the bathroom you are either leaving the light
on to ensure the fan clears the moisture, or you are turning off the
fan before the moisture is cleared. The former wastes electricity, the
latter can result in mold and peeling paint. (This assumes showers/
baths are taken in the bathroom)
In any event, you're wasting electricity every time you turn on the
light (and therefore the fan) even if you're just combing your hair or
brushing your teeth, assuming you have both.
It's back EMF (electro-motive-force) from the motor starting up. This
actually causes the switch contacts to "bounce" making the noise and
an internal spark. With squirrel motors the current circulates around
the coil and the rotor (squirrel) inside the coil "follows" that
circulating current. For there to be zero back EMF the rotor would
have to be in perfect speed synch with the coil current flow, but it
never is, especially at start up time when it is standing still.
Cheap paddle ceiling fans can also show this symptom, but the more
expensive fans have a capacitor circuit to absorb some of the back
emf, the real cheap ceiling fans dont so they make a noise too I've
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