wiring question

Discussion in 'Shop Talk' started by .netDude, Nov 24, 2006.

  1. .netDude

    .netDude Well-Known Member

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    I have a light box in the middle of the room with 14/3 coming in and out for 2 3way switches. I need to be able to attach 2 2-wire cables to this for outlets. Where do I connect them to the 3 way wires? It seems like it'll be pretty crowded in the box, should I make connections in a separate junction box and just run the needed wires to the light fixture box? Also, the 3-wire cable is 14/3, one of the additional lines going into the box is 12/2, any issues with this?
    Can I split a single cable, using pigtails, to two separate switches? The reason I as is that there is one 12/2 coming into the room, that goes to an outlet, then to a switch box containing a switch for the fan and a 3way switch for the light.
    Thanks.
     
  2. CatsPaw

    CatsPaw Who...me?

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    If what you describe in the second paragraph is accurate, then the only place there would be power would be in the outlet.

    So you would have to take power off from there. You might have some access to the power in the switch box. It all depends on whether you have a crawl with access under the house or attic or what as far as burying the wires.

    Logically speaking power would not be in the light box except when the light is turned on.

    As far as the 12-2 in the light box, well, that could be the power for the light. Kinda bass-ackwards. Not sure if I would put that many wires in that one box.

    These things are hard to understand just from a description rather than actually testing the circuit to see what's what.
     

  3. .netDude

    .netDude Well-Known Member

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    I have access to the walls and ceiling joists.
    So, I can't do this?:
    12/2 power from wall to outlet-> from outlet 12/2 to -> double switchbox, 1 2way 1 3way switches, 14/3 to center light -> from there, 14/3 to other 3 way switch, 12/2 to outlet, 12/2 to outlet?

    Should I run separate 14/3 for the switches and light, and a completely separate 12/2 to the outlets? I thought by tapping into the light box, I could eliminate having to run all that extra cable.
     
  4. tyusclan

    tyusclan Well-Known Member

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    You don't want to tap into the light box. The power has to go to the switch first on a 3-way, and you won't have power when the light's off. How many total drops (outlets and lights) do you have on that circuit now? If you have 7 or more run a seperate circuit from the panel. If you have less than 7 you can tie onto the power wire in the box where the light switches are, and then run to your outlets. Just be sure to get on the hot side coming from the panel box.
     
  5. retire2$

    retire2$ Well-Known Member

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    Some things to consider before your question could be answered:

    Will adding more boxes overload the circuit?

    What is the size of the box you want to tap off of. Each size box (cubic inches) has a limit for the number of wires that can be placed in the box.

    What is the circuit breaker amperage - You don't want to use 12-2 wire with a 15 amp breaker.

    How difficult would it be to run another circuit? Do you have enough space in the panel?
     
  6. CatsPaw

    CatsPaw Who...me?

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    First of all, I should mention that asking electrical questions on here is dangerous.

    Second, I have a code ( and physical) problem to address. 14-3 should not be connected to a 20A circuit. Logically, the 12-2 coming in with power would be 20A. I don't know that it is. It might have a 15A breaker on it and they just happened to use 12-2. That circuit would have to be checked at the load center.

    Next, The light circuit should be power coming in [neutral and hot] to the switch box. Hot is connected to the common on the 3-way. Black and Red of the 3-wire are connected to the other to terminals. White is nutted to white. Here's where things get off-center. The 3-wire should then go to the other 3-way switch, black and red to the switched terminals. a 2-wire would then go from there to the light fixture, black
    to the common of the 3-way switch and white from the 3-wire is nutted through to the white of the 2-wire. With all that, the only wire in the light box should be a 2-wire.

    There are other ways of doing it but they can confuse things for guys down the road.

    I wouldn't know what the 12-2 in the light box would be without the hands on testing. Unless the light box is for a fan/light combo. In which case I can guess it is from the single pole (2-way switch).

    My last questions would be why is the 14-3 running through the lite box. It would not necessarily need to. Is it going straight thru or are there connections made to it in the lite box?

    I would pull power off of one of the outlets and go to the new outlet(s). I know this probably doesn't answer your question but maybe makes you dangerous enough to understand the circuit alittle better to figure something out.
     
  7. tiogacounty

    tiogacounty Well-Known Member

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    Amen to that. You have done an admirable job of explaining as much as you possible can without actually being there, tester in hand.
    Just to clarify a few points in other posts:
    1. "you don't want to use 12-2 on a 15 amp breaker". Nothing wrong with oversizing wiring, undersizing is a problem. So, you don't want to use 14/2 on a 20 amp. breaker.
    2. " if you have less than seven drops" well this is sort of right. the code uses an arbitrary value of 1.8 amps per device, in the absence of a specific load. This results in a lot of guys using a figure of seven devices per 15 amp breaker, and nine per 20 amp. The problem is that it's not a code requirement, and it can lead to poor installation practices. for instance there are many cases where seven outlets would lead to an overloaded circuit, and seven dedicated lights would be a very lightly loaded circuit. In this case it's real important to figure out exactly why there is 12/2 and 14/2 on the same circuit, what the breaker size is, and how many devices are on the circuit already.
     
  8. rambler

    rambler Well-Known Member Supporter

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    To wire an outlet these days, you need to be running a ground wire. Is ground avalialable in those middle boxes?

    You need a solid power source to tap into. _Typically_ the live power gets shifted around between 2 of the 3 wires in a 3-way or 4-way setup, and so you _typically_ couldn't tap those for an outlet - it would only work when one switch was in the right position. You mention several other wires (the 12ga esp.), which clouds the issue, as some said we can't see/ test what you actually have.

    If it is not outright totally against the code (I thought it was?) it is a bad idea to go from a 14ga wire up to a 12ga wire. Someone will 'assume' it is a 20 amp curcuit and try to go to 20 amps, which the 14ga can't handle. You should only tap a 14ga off of a 14ga wire.

    By _far_, it would be better to run seperate 12ga (2 wires plus ground) to the outlets. Yup, it will be more wire. But it will be righter.

    It might be possible to figure out what you are trying to do, but on the surface it wouldn't look like it would ever work.

    --->Paul
     
  9. CatsPaw

    CatsPaw Who...me?

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    Thanks Tioga.....Funny...I just came from the bale house thread.....:D

    If it comes down to it, you can seperate the connections, do some continuity testing to determine what wire is what and where. But, I think the bottom line would still be to just come from the old outlet and run to the new outlets. That probably takes care of all the other crazy things that may or may not be going on. AND would avoid any erroneous things we might be telling/confusing you with. :)

    I always go with what I know is the right way/first instinct....to paraphrase the above...it's just usually righter! :D
     
  10. dennisjp

    dennisjp dennisjp

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    For a 3-way switch situation, the power should be coming into one of the two switches.
    I have wired several new homes and worked on wireing in many older homes, and have never seen power coming into the light box on a 3-way circuit to start with. I am setting here trying to figure out if it would even work. It may be posible to do it, but I would have to be there looking at it and as several others has said, with a tester in hand.
    Is there a chance there is a receptical in the room where a lamp would come on when the lights are on. That may be where the 12/2 is going to.
    Also, the 14 wire should be connected to a 15 amp breaker. 12 wire is rated for up to 20 amps, but you can use it on a 15 amp breaker as someone said. As far as that goes, you could use 10/2 on a 15 amp breaker but there is no use, unless you just happen to have the wire.
    #8 wire = 40 amps
    #10 wire = 30 amps
    #12 wire = 20 amps
    #14 wire = 15 amps

    While I am on this subject, can some one tell me why it is leagal to use a receptical that is rated at 15 amps on a 20 amp circuit. :shrug:
    All the contractor around here use them because there are so many in a new home and the diference between the 15 amp/ $.49 and 20 amp $4.68 recepticals.
    The inspectors say it is because you have several recepitcals on one circuit, but that still leaves someone being able to put a 20 amp load on just one 15 amp receptical :shrug:
    I can't bi#%$, because that is what I always did also, because you can't bid a job and get it if you add the cost to it, but it still seems odd to me.
    A lot of homes have burned down because some one had an electric heater pluged into one for long periods of time, even though 1,500 watts is only 12.5 amps @ 120 volts, but the circuit moved on to the tv, etc.
    And I don't see why there should be as much difference in the cost of them.
     
  11. dennisjp

    dennisjp dennisjp

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    For a 3-way switch situation, the power should be coming into one of the two switched.
    I have wired several new homes and worked on wireing in many older homes, and have never seen power coming into the light box to start with. I am setting here trying to figure out if it would even work. It may be posible to do it, but I would have to be there looking at it and as several others has said, with a tester in hand.
    Is there a chance there is a receptical in the room where a lamp would come on when the lights are on. That may be where the 12/2 is going to.
    Also, the 14 wire should be connected to a 15 amp breaker. 12 wire is rated for up to 20 amps, but you can use it on a 15 amp breaker as someone said. As far as that goes, you could use 10/2 on a 15 amp breaker but there is no use, unless you just happen to have the wire.
    #8 wire = 40 amps
    #10 wire = 30 amps
    #12 wire = 20 amps
    #14 wire = 15 amps

    While I am on this subject, can some one tell me why it is leagal to use a receptical that is rated at 15 amps on a 20 amp circuit. :shrug:
    All the contractor around here use them because there are so many in a new home and the diference between the 15 amp/ $.49 and 20 amp $4.68 recepticals.
    The inspectors say it is because you have several recepitcals on one circuit, but that still leaves someone being able to put a 20 amp load on just one 15 amp receptical :shrug:
    I can't bi#%$, because that is what I always did also, because you can't bid a job and get it if you add the cost to it, but it still seems odd to me.
    A lot of homes have burned down because some one had an electric heater pluged into one for long periods of time, even though 1,500 watts is only 12.5 amps @ 120 volts, but the circuit moved on to the tv, etc.
    And I don't see why there should be as much difference in the cost of them.
     
  12. dennisjp

    dennisjp dennisjp

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    Never seen power coming into a 3-way light box is what I meant. :shrug:
     
  13. tiogacounty

    tiogacounty Well-Known Member

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    Dennis, it is possible to send power to a light box then head off to the three way switches. It's unusual in residential work, as it's not an efficent way to use romex, but it's a little more prevelant where conduit and individual wires are pulled. I'll try to talk my way through this. Take a two wire w/ a hot and neutral to the light. The neutral ends at the fixture . Take the hot and send it on a two wire to the first three way. now run a three wire from one three way to the next. The power comes from the light to the common on the first three way, down the travellers to the next three way, then back to the light. This is a switching only situation. There are only hots and a ground. The switched hot returns on the other leg of the two wire, returning to the light. I wish my keyboard had an etchi-sketch, it's hard to explain.
    Your 15 amp/20 amp receptacle question is a valid one. Personally, I like the fact that you can no longer backwire(pushwire) a #12 into a receptacle. Pushwiring the backs of receptacles is a garbage technique that never should of been allowed. I also never use the 15 amp, builder grade devices. I get "spec" grade 15 amp devices from places like Home Depot. They are available in different grades and can be had for less than $2 each. They are dramatically better than the cheapies.
     
  14. CatsPaw

    CatsPaw Who...me?

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    15A outlet on a 20A circuit is allowed because the physical outlet it considered a fusable link, supposedly protecting the circuit "properly".

    Technically speaking a 20A device should only have a 20A plug on it which won't go into a 15A outlet. But, "they" never make things that way.

    I would rather see a 20A outlet on a 20A circuit.
     
  15. idahodave

    idahodave Well-Known Member

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    I think that there is a misunderstanding of the 15 amp rated duplex receptacle.

    It's really a pair of 15 amp rated receptacles that make one outlet. EACH plug connection is rated for 15 amps. Code says its OK on a 20 amp circuit, so it must survive at 20 amps.

    Also code approved products cannot use more than 80% of the plug rating which is 12 amps or 1500 watts for a standard two parallel bladed plug.
     
  16. CatsPaw

    CatsPaw Who...me?

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    That fusable link thing was an explaination given to me by a building inspector. An he said he wasn't clear on it either.

    Idahodave, here's alittle challenge since I'm not getting your explaination completely.

    If it's a pair (even though they are linked) wouldn't that imply that even derated to 80% you could pull 12 through each totalling 24A's? Or are you saying that the outlet would survive 15A thru each (totalling 30A) and so should survive well enough for the circuit to blow, protecting the overall circuit?

    Did I just hijack this thread? didn't mean to. Was thinking we were still in the same, sorta, close to, the subject matter. sorry
     
  17. idahodave

    idahodave Well-Known Member

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    In short yes...

    Everything downstream of a 20 amp breaker must be constructed to survive the maximum current the breaker can supply before it trips, otherwise it wouldn't be allowed.

    The 24 amp load case might take several minutes for the breaker to trip.

    Sorry for the hijack
     
  18. dennisjp

    dennisjp dennisjp

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    I am still lost on this one.
    Lets say you wire a room on a 20 A circuit. The first receptical is rated 15 A.
    It is wired with 12/2 w Grn.
    You plug in a 1,500 heater which is 12.5 amps. You plug a drop cord in, down stream and run it out side to, lets just say something that draws more than 2.5 amps, but less than 7.5 amps.
    The breaker won't kick, but the receptical is still overloaded. How does that pass code. :shrug:
    tiogacounty, I also think the push wires should never have been invented. If I can't hard wire them and tighten them down with a screw, I am not going to install them. Most of the recepticals I have replaced was with the wire pushed in the back and the problem was simple. Bad connection. Burned it up and many of them darn near burned the house up along with it.
    That is JMHO
    God Bless
    Dennis
     
  19. CatsPaw

    CatsPaw Who...me?

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    See! What Dennis said......I could only assume that even though the outlet is spec'd at 15A, the manufacturer actually built it for 20A. And if so, why don't they call it a 20A recepticle (disregarding derating, since by Dennis' example you can easily over-ride an 80% derating by using two appliances, one in each part of the recepticle.)

    o.k. this a really starting to look like a hijkacking now. bad hijackers, bad!
     
  20. dennisjp

    dennisjp dennisjp

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    I liker that cat. Bad hijackers, bad.
    Actually, unless he tells us more, I don't see that we can help him any more than we have, so hijack until he comes back and then we will go back to work, lol
    God Bless
    Dennis