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Old 01-10-2010, 10:09 AM   #1
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Central exhaust fan


I need advice on wiring a 7 button electronic timer sw to control a central exhaust fan in one bathroom and a single pole operate the same fan in another. I have since "blown" a $30 electronic sw.
The electronic sw has a "red" lead for the load (fan) and black for hot source, a neutral, and grd. The red is connected to a black sw wire at the fan, the white to the neutral. This should control the fan for B/R "A". In bathroom "B", I have only room for a shallow box and single pole sw. It breaks power to the fan through the Black sw wire, as well.
Now, if the Fan is on in B/R "A" and the timer is is on in B/R "B", as well, could there be an issue with the electronic due to the same potential being applied from another pwr. source?
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Old 01-10-2010, 01:44 PM   #2
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There shouldn't. Can you clarify exactly how you wired these switches to "blow" your timer?

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Old 01-10-2010, 02:34 PM   #3
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The fan, timer switch, and the single pole switch should all be on the same circuit / breaker.

You could be supplying 240 volts if on separate breakers - a random chance thing.

And motors can place all sorts of electrical "noise" on electric wires. This can "fry" electronic gizmos. Be sure the electronic timer can be used for electric motors / fans. Read all the warnings in the instructions for the timer.

Then sometimes "back feeding" power to the output of an electronic device can fry it. This would be via the 2nd single pole switch.

All sorts of possible problems! So what to do?

The best way to troubleshoot a problem such as this is to isolate the trouble.

1st be sure everything is on the same circuit and circuit breaker.

Then install a regular single pole switch where the timer goes. Get the basic fan and both switches working. Then you know the fan, circuits, wiring, and switches all work ok and everything is installed ok.

Then this would leave just the timer. Install the timer again. If there are problems, then you would know it was just the timer and not anything else.

The timer can be "isolated" from electrical noise from the fan or back feeding of power from the other switch with the use of a "contactor" which is a relay. More on this...

How relays work...
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