"** Frank **" wrote in message
...

"Jeff Wisnia" wrote in message
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** Frank ** wrote:
I have a clothes dryer with a 120VAC push to start button. In measuring
the terminals, both sides are hot (120V) with respect to ground and zero
volts across the two terminals. Why is that?

I thought there was a short on one side of the push button but the dryer
is working properly. Normally it should be hot only on one side.




We could make more intelligent guesses if the OP told us whether those
measurements existed with the dryer running, off or either.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.


The push button is normally open. Measurements existed with dryer off.
Push to start means the contacts short across the terminals. I use a very
old but reliable analog Simpson 260 meter for the measurements.

I think, as some other posters have mentioned, that once the button is
pushed the timer, a relay, or a centrifugal switch on the motor closes
contacts in parallel with the switch. This keeps the dryer running after you
release the start button. It's a common system used in motor controls with
seperate start and stop momentary pushbuttons. However, this would require
your measurements to have been made with the dryer running. Basically, if
there is zero volts across a normally open switch, closing it cannot do
anything, as would be required for the dryer to start when the button is
pressed. You might want to check your measurements again. There could be a
schematic diagram somewhere inside the dryer.

Don Young