Exhaust fan switching

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You could still use two 3-ways and a 4-way, along with indicator lights at each switch that don't require additional wiring:

At each switch, wire a pair of 100K 1/4w resistors in series, wire the pair across the travelers, and wire an NE-2 neon bulb between the resistor junction and the neutral.

When the load is on, so are the bulbs. If the bulbs won't go off, the load is open. This is great for remotely-located lights.
 
I have this exact same scenario for 4 bathrooms and one ex. fan for a warehouse. Four single pole switches on switch loops driving a contactor is what I'm going with. Occ. sensors would be ideal, but not if they weren't bid....
 
I usually install timer switches but have not used the relay. I used to feed the power in the attic and drop down with switch legs but it is still sending current in 2 directions (paralleling) for a distance when both switches are on. I think the relay or 3 ways is the only way to legitimately do this.
 
What about using the sp. wind up mechanical timers I used them on tan beds a lot.

To me as far as the paralled switch loops, I dont think this is what the code panel
had in mind when they made this code.They where trying to limit the use of smaller
conductors for feeds if it wheren't for this code instead of running 6/3 to the range
a lot of contractors would probably parallel 3 # 10/3 nm cables what a mess this could be.

But I do like Larry's idea about the neon lamps.:)

Ronald
 
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ronaldrc said:
To me as far as the paralled switch loops, I dont think this is what the code panel
had in mind when they made this code.They where trying to limit the use of smaller conductors for feeds if it wheren't for this code instead of running 6/3 to the rangea lot of contractors would probably parallel 3 # 10/3 nm cables what a mess this could be.
Ronals
Click to expand...


I agree and I really don't have a big issue with it but it can be rejected by an AHJ.
 
Bob

My inspector once told me he likes to use a little common sense.
Hes a very good inspector.

To answer your question no. But that does not make my opinion wrong.:)
 
Cow said:
I have this exact same scenario for 4 bathrooms and one ex. fan for a warehouse. Four single pole switches on switch loops driving a contactor is what I'm going with. Occ. sensors would be ideal, but not if they weren't bid....
Click to expand...

Hope you warned them that it will likely run 24/7
 
Cow said:
Four single pole switches on switch loops driving a contactor is what I'm going with. Occ. sensors would be ideal, but not if they weren't bid....
Click to expand...
Technically speaking, when more than one switch is on, you still have paralleled conductors. The only difference is the load is a coil instead of the fan.

I don't have a problem with paralleled switching. I just mentioned it because others have.
 
310.4(A) General. Aluminum, copper-clad aluminum, or copper
conductors of size 1/0 AWG and larger, comprising each
phase, polarity, neutral, or grounded circuit conductor shall
be permitted to be connected in parallel (electrically joined
at both ends).
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:mad:

Anyone know when and or why they removed "to form a single conductor" from the end of (electrically joined at both ends)? It's in the '99.

Not allowing parallel switching is ridiculous, we're not trying to make a larger conductor here, just operate a fixed load from multiple locations.
 
I think the OP was wondering if there was anything wrong with energizing the secondary side of the remaining switches when any one of the switches was turned on since they all went to a common load and the answer is no.

As long as the switchlegs are terminated at a common point this is going to be the case whether it is at the motor,or coil on a contactor.
Even on an Occ Sensor with a common power pack.

As far as the parallel conductors issue,this is not a parallel conductor.
You only have 1 conductor leaving the breaker,not 2.
It is a single circuit that has a common load controlled by switching from several locations.

Use a 1p switch but yes it will probably stay running all the time.
Use a spring wound timer if you want at 3 locations, although not standard in a commercial application probably the simplest and will shut off once it times out.
Use Occ Sensors with a common power pack, most common
You could get as fancy or as simple as you need to.

Point is the back feed on the secondary side of the switches is pretty common.

You just need to shut the circuit off before maintaining it so the people turning on the switch in room 2 and 3 dont light you up while your working on switch #1
 
LarryFine said:
Technically speaking, when more than one switch is on, you still have paralleled conductors. The only difference is the load is a coil instead of the fan.

I don't have a problem with paralleled switching. I just mentioned it because others have.
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I agree Larry but this not done to increase the capacity but for control reasons.

I sure would not increase the cost, complexity and durablity of the circuits by adding
a relay because of sematics.

Sometime we do need to use common sense.
 
If you want to use relays why not use touch plate?

Cick here for Example

I don't know if you are familiar with them or not they fit in a 1/2" KO to mount in a metal box ,low voltage side will be out side of box. You may use twisted 18/2 to your low voltage push button switches. You will also need a 40va
120/24 VAC transformer for low voltage AC supply. I also recommend a in line low voltage fuse. :)
 
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