inline exhaust fan with 2 parallel switches

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  #1  
Old 05-11-12, 12:50 PM
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inline exhaust fan with 2 parallel switches

I apologize in advance if I use incorrect terms.

I have 2 adjacent bathrooms - one with an exhaust fan and wone without. The existing fan is noisy and only vented into the attic. I would like to replace it with a single remote/inline fan that will exhaust air from both bathrooms at the same time so I only need to have one fan. My issue for this forum is how to take the existing wiring for the one fan and change it to work as follows:

Each bathroom would have a mechanical timer switch. If either timer switch is on, the fan will run. As long as at least one timer switch is on, the fan will run. I am not looking for 3-way switches.

I can probably come up with a solution but it would be safer for someone who knows this stuff to tell me the right way to do it. This seems straightforward enough that it shouldn't require the $225 bid I had from an electrician.
 
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  #2  
Old 05-11-12, 01:03 PM
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Yes, very easy to do using two spring-wound time switches wired in parallel. I would suggest not trying it with electronic (digital) timers.
 
  #3  
Old 05-11-12, 01:04 PM
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I understand. Now how do I wire it? what cable is used where?
 
  #4  
Old 05-11-12, 01:13 PM
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You need to use a wiring method appropriate for your area. In Chicago , New York City and a few other places this would mean conduit but most residences are allowed to use type NM cable. The size required depends on the circuit breaker supplying power to the fan.

I am assuming that you know how to wire a single switch in series with the power and fan (if not I have another suggestion) you would simply connect the first timer instead of a switch, spring-would timers only have two power connections, and then connect the second timer to exactly the same points as the first time.
 
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Old 05-11-12, 01:33 PM
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I am pretty sure that NM is acceptable as the only conduit in the house now is where the wire would otherwise be exposed to the living space.

I was expecting to:

1. replace current fan switch with mechanical timer
2. use existing cabling from existing switch to power new fan
3. run cable from first mechnical timer to second mechanical timer to provide power (NMB 14/2)
4. Run new cable from second mechanical timer to fan (NMB 14/2)
5. connect wires from both timers to the hot lead on the fan
 
  #6  
Old 05-11-12, 01:45 PM
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Assuming the power comes into the existing switch box rather than at the fan you would need to run a three-conductor cable from the first timer to the second timer so that either timer receives a "hot" conductor. From the second time a two-conductor cable to the fan. At the first timer connect the incoming power cable white to the three-conductor white, the incoming power cable black to the three-conductor black AND the timer terminal and the red of the three conductor cable connects to the second timer terminal.

At the second timer the black of the three-conductor cable connects to the timer terminal, the red of the three-conductor cable connects to the second timer terminal along with the black of the two conductor cable going to the fan. The white of the three-conductor cable connects to the white of the two-conductor cable going to the fan. At the fan the white and black conductors connect to the appropriate terminals on the fan.

Now if power instead comes first to the fan it is a bit easier and you will only need to use a second two-conductor cable from the second timer OR you can run a two conductor cable from the first timer to the second. If this is your wiring arrangement I can give you the details.
 
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