2 circuits, one switch??

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  #1  
Old 08-22-05, 08:24 AM
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Question 2 circuits, one switch??

Hi,

This might be easy, but I'm not getting it...

Our new bathroom will have an exhaust fan that we want to be activated when someone turns on the lights. (people usually don't turn on a separate switch) The fan needs to be on a GFI circuit - which will be the bathroom outlets, but we don't want the lights on that circuit so that if an outlet interrupts, someone isn't left in the dark. So, how can we have a single "light switch" turn on both the lights on the lighting circuit and the fan on the GFI circuit? Are there any code issues w/this?

Thank you!
 
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Old 08-22-05, 08:36 AM
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You can set this up with a double pole switch if you have enough wires between the switch box and the fan/light fixture. Please describe all of the wires you have in each box, or indicate if this is new construction.

Why must the fan have GFCI protection? It is not typical.
 
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Old 08-22-05, 08:36 AM
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The fan needs to be on a GFI circuit
It does? Why? None of mine are. Experts? If it truly does, trying to put it on the same switch as the lights is difficult. Why not just install a motion detector for the fan so it will be switched on when someone enters the bathroom and off after they leave?

Doug M.
 
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Old 08-22-05, 08:44 AM
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This is new construction so wiring can be installed as needed...

I thought Panasonic stated that it had to be on a GFI. Motion sensor won't work when someone is in the shower behind glass.
 
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Old 08-22-05, 09:21 AM
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I thought Panasonic stated that it had to be on a GFI.
Let us know when you find out for sure.

Put the bathroom receptacle on one circuit. Put the light and fan on a second circuit. If the fan really needs GFCI protection (which is pretty rare), then use a second GFCI. In my opinion, this "left in the dark" concern is highly overrated, both because it happens so rarely, and because it usually isn't a big deal even when it does happen. In many homes, you are left in the dark more often by a power failure than a tripped circuit. People seem to cope pretty well.
 
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Old 08-22-05, 09:47 AM
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I presume that you already know how to wire this if you were going to use two separate single pole switches, for example power to switch box, switch installed in hot wires, neutral and switched hot to load. Of course, you could also use a switch loop, with power going to the load and a loop lead going to the switch.

Given this, what you really want is two switches that are somehow forced to operate at the same time. This is available; it is called a double pole switch, and externally has a single operator (toggle), but internally is two entirely separate switches, capable of switching two entirely separate circuits.

http://www.doityourself.com/store/u172742.htm

Just wire the two sides up like two separate switches, and you can control two loads; either on entirely separate circuits, or one load fed 'upstream' of a GFCI and the other load 'downstream' of a GFCI.

The only caution is that you must _not_ connect the neutrals of the two circuits together; keep both circuits independent. This applies for two separate circuits, or for a single circuit separated by the GFCI. Just wire this at two totally separate circuits, with separate neutrals and such, as though you were wiring two separate switches. As necessary, run separate cables from your power source.

Note: I concur with the above assessments about needing the fan on the GFCI; all of the bathroom fans that I've encountered or read about did not require GFCI protection.

Additionally, I strongly prefer having the fan on its own switch, that way I can run it to dry out the room without having to leave the light on.

-Jon
 
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Old 08-22-05, 09:57 AM
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Additionally, I strongly prefer having the fan on its own switch, that way I can run it to dry out the room without having to leave the light on.
Me too, sometimes for the vice-versa reason. If I just go in there to comb my hair, I'd prefer not to listen to the fan drone on.
 
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Old 08-22-05, 01:17 PM
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Most bath exhaust fans do require ground-fault protection but only when installed within the tub enclosure. This is usually stated in the instructions or on a sticker inside the unit.
 
  #9  
Old 08-22-05, 05:03 PM
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If you have a two pole togglw switch, each circuit will have to be on the same circuit breaker throw (either the same breaker pole, or a two pole breaker.).

That said:
Do this
Run the lights before the GFI on one pole of the switch. Run the fan off the other pole after the GFCI outlet, optionally feeding the GFCI from the other leg on a shared neutral common trip circuit.
 
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Old 08-22-05, 08:07 PM
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Bolted Fault is correct - when the fan is above a tub or shower it must be GFI according to Panasonic's literature.
 
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Old 08-23-05, 06:50 AM
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So is yours above the shower or tub?
 
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