3-way switch and wire guage questions

[Mike83]

I started installing a ceiling fan yesterday (new location) and I planned to pull power from an existing switch. Well, to my dismay I find out you cannot in any way I know of pull power from the leg end of a 3-way switch due to the traveller wires changing from hot to neutral. I can pull power from the garage since the other side of the wall of the family room is the garage, but that would be a 20 amp circuit and I already spent an unreal amount of effort pulling 14-ga wire from the switch location to the box in the ceiling by crawling in the attic.

So, my two questions:

1) Is there any way I can get a constant hot supply to my fan switch with only the leg end 3-way switch next to it?

If not:

2) Can I use the 14 ga wire already installed for the fan if I pull power from the 20 amp garage circuit (the 14 ga would only exist from the switch to the fan). Could I maybe just downgrade the breaker to 15 amp as a last resort? Fwiw I don't use anything that pull more than 13 amps from the garage circuit now but in consideration of future use would this be feasible?

Thanks for the help and hopefully I make sense with my explanation. This project has become bigger than I imagined.

 

[ArthurPE]

a 3 way switch does not switch H and N...
the travellers run between the switched legs and depending how it's wired, and which 3 way you are wired to, you may have a constant 120 leg...
the neutral is often available at the switch (although is passes thru and is not used)

if you draw 13A I would not go to a 15A, it's supposed to be oversized by 25%...

a couple of examples:
power at load

power at switch

a bunch of drawings: http://images.google.com/images?hl=en&q=3 way switch diagram&um=1&ie=UTF-8&sa=N&tab=wi

 

[mrb]

you cannot supply a circuit containing 14ga wire from a 20a circuit. Your options (besides replace the wires) are replace the breaker with a 15a breaker (I would tag the wire inside the panel as needing a 15a breaker due to #14 in the circuit) or install a small 2 breaker subpanel with a 15a breaker in it (theyre cheap, like $12) where you tap into the garage circuit (the panel must be accessable) to protect the #14 wire at 15 amps.

 

[hidollartoys]

If you have a neutral "feed through" in the box that you have pulled the 14 ga to then yes but that circuit should be a 15 amp circuit as explaned by mrb.

Arthur, your second diaghram does not show a circuit with "power at switch". It shows "power at load".

 

[ArthurPE]

If you have a neutral "feed through" in the box that you have pulled the 14 ga to then yes but that circuit should be a 15 amp circuit as explaned by mrb.

Arthur, your second diaghram does not show a circuit with "power at switch". It shows "power at load".

cut and pasted wrong one...in a rush

 

[sberry]

This is just in theory, not really advocating anything not code but if this 14 feeds a fixture with a known load and no way to plug anything in to it to overload the circuit then the real danger of using lighter wire in this circuit is minimal, similar to a fixture wire.

 

[mrb]

This is just in theory, not really advocating anything not code but if this 14 feeds a fixture with a known load and no way to plug anything in to it to overload the circuit then the real danger of using lighter wire in this circuit is minimal, similar to a fixture wire.

true, but then you have an unrelated fire and your insurance co finds the #14 hooked to #12 and refuses to pay the claim due to illegal DIY wiring.

There is no reason to not do this right.

 

[sberry]

There are billions of dollars of sub standard work insured each day. If it was a perfect world you wouldnt need the insurance.

 

[sberry]

I find a lamp cord during a re-wire the other day, been in there 50 yrs on a switch loop and perform perfectly. No one knew it was there but the ins co gladly take premiums on this property all those years. I dont recall anywhere in my policy that says they wont ins anything that hasnt been inspected.

 

[mrb]

I find a lamp cord during a re-wire the other day, been in there 50 yrs on a switch loop and perform perfectly. No one knew it was there but the ins co gladly take premiums on this property all those years. I dont recall anywhere in my policy that says they wont ins anything that hasnt been inspected.

they gladly take the premiums, and look for any reason to delay or avoid a payout. Happens all the time.