wiring 3way switches to controloutlets


  #1  
Old 02-24-04, 03:22 PM
ccsm
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wiring 3way switches to controloutlets

I need help >>> I am wiring my garage and want 3way switches to control 4 duplex outlets... one switch at either end of a 40' room with 4 outlets(in ceiling) spaced equally in a line from switch to switch ie; sw ..... 0 .....0 ......X..... 0 ..... sw

**NOTE: my LITTLE DIAGRAM DIDN'T TURN OUT RIGHT: The power source enters at a rt. angle where I have placed the X.
SORRY!
ll


From the source I have run 12-2/wg .... and from switch to boxes to switch I have 14-3/wg ??? I have no Idea how to wire this thing.

ANY HELP WILL BE GREATLY APPRICIATED .. I MUST FIND THIS OUT BEFORE MY BOASTFUL SON ARRIVES. ccsm@ultraweb.net
Jess.
 
  #2  
Old 02-24-04, 03:27 PM
J
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Let "=" mean 12/3 and "-" mean 12/2. Here are your options:
  1. S1=S2-R1-R2-R3-R4.
  2. S1=R1=S2, and R1-R2-R3-R4.
I assume you wired S1=R1=R2=R3=R4=S2. There is no way to make that work. Recable in one of the two options I presented.
 
  #3  
Old 02-26-04, 08:59 AM
ccsm
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3way switches

Thank you John for your prompt reply to my qeastion concerning wiring my garage with 3way switches ... I did however take some verbal abuse from my son whom used the wrenching phrase .. "I TOLD YOU SO!" I did however, think that ther would be other replies .. My gratitude again John. Jess
 
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Old 02-26-04, 09:57 AM
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As you have described things, you cannot do what you want to do with the cable that you have run. However, given that you have to run new cable anyway, there is an additional option which you might like. The only advantage is that you would have a single cable run between your various device boxes, rather than having to loop back and forth going from the source to the two switches and then to the receptacles.

Using - to mean 12/2, and = to mean 12/3, and # to mean 12/4!

You can then wire:
S1=R1#R2#R3#R4=S2

By using 12/4, you can provide both an un-switched hot and a neutral to all of the outlets. In fact if you run 12/4 to the switches as well, then you can have un-switched power available at the switches if you so desire. (By running 12/3 to the switches, you have an un-switched 'hot' but don't have the corresponding 'neutral'.)

To wire this up, you connect your un-switched hot to one of the _travaller_ terminals of each three way switch. You then run a traveller between the common terminals of the three way switches, and finally run a traveller between the other traveller terminals of the three way switches. This final traveller is your switched line. You then connect your receptacles between this switched line and neutral.

Say that your 12/3 has Black, Red, White, Green and your 12/4 has Black, Red, Blue, White, Green.

In S1:
T1 to White taped with Black (switch loop re-label)
T2 to Black
C to Red.

In R1:
White taped black from S1 joins to Blue from R2
Red from S1 joins to Red from R2
Black from S1 joins Black from R2, pigtails to black to receptacle
White from R2 goes to receptacle

In R2:
Blue from R1 joins to Blue from R3
Red from R1 joins to Red from R3
Black from R1 joins to Black from R3, pigtails to black to receptacle
White from R1 joins to White from R3, pigtails to white to receptacle

In R3
Blue from R2 joins to Blue from R4 joins to Black from supply
Red from R2 joins to Red from R4
Black from R2 joins to Black from R4, pigtails to black to receptacle
White from R2 joins to White from R4 joins to white from supply, pigtails to white to receptacle

In R4
Blue from R3 joins to white coded Black from S2
Red from R3 joins to Red from S2
Black from R3 joins to Black from S2, pigtails to black to receptacle
White from R3 goes to receptacle

In S2
T1 to White taped with Black (switch loop re-label)
T2 to Black
C to Red.

The only part of this is a problem is getting the 12/4 wire. You may find it easier to get 12-2-2 wire, which has _two_ white wires in it. This wire is used for AFCI wiring where it lets you run two circuits on two separate AFCI circuit breakers. It has four conductors plus ground, and in all respects but one is 12/4 wire. The only problem is that it has two white wires (one with a red stripe) rather than one white wire and 3 'hot' wires (and the ground, of course) It is arguable if it would meet code to re-code (tape) one of the whites in 12-2-2 as a hot for this application.

Please see http://www.geocities.com/gary_wachs/ElectriPuzzles.html for some interesting tidbits on 3 way switches. The circuit described above is very similar to the 'solution to puzzle two on that page.

-Jon
 
  #5  
Old 02-26-04, 11:16 AM
ccsm
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3way switches

Thanks for your reply Jon ... This project wouldn't have been such a big deal had I talked to you guyes FIRST!! What I did was to run 12/3 from S1>>R1>>>R2>>X>>R3>>>R4>>S2 With the power source 12/2 entering the scheme at the (X) The big problem that I have is that I had run everything in i/2" conduit and was hoping that I woulfd not have to tear it all out. I think I could feed a single 12ga wire through the conduit from R1 thru R2 & R3 to R4 without too much difficuility. ???? Jess
 
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Old 02-26-04, 11:23 AM
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I'm confused now, and need to to answer a couple of questions.

When you say you ran 12/3, do you mean 12/3 NM ('Romex' cable)?

When you say that you ran everything in 1/2" conduit, do you mean that you fed the NM into the conduit?

Is the conduit complete between the device boxes, meaning with appropriate fittings and the like?

Thanks.
Jon
 
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Old 02-26-04, 11:31 AM
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Additionally, how _large_ are the various boxes that you installed? In particular, do you know the volume in cubic inches of the boxes?

-Jon
 
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Old 02-26-04, 11:34 AM
ccsm
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Thanks again Jon! Yes I ran 12/2 with gr. nm cable through conduit to the (x) as the power source. I ran 12/3 with gr. nm cable from S1 through R1>R2> round junction box(x)>R3>R4 to S2 all with fittings etc., the conduit I should note is PVC type and PVC type boxes. Thanks Jess
 
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Old 02-26-04, 11:34 AM
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If you ran #12 from the source with a 20 amp breaker, be sure to use 20 amp rated switches.
 
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Old 02-26-04, 11:39 AM
ccsm
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3way switches

txdiyguy, Thanks ... I did and the Rec"s are also comm duty. Jess
 
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Old 02-26-04, 11:59 AM
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Okay, I bet that you had a heck of a time pulling the NM into the conduit I would have to get more information to double check the numbers, but I believe that the situation you describe violates 'conduit fill' rules, which basically say how much stuff you can put into a conduit. For calculating conduit fill, you have to treat a cable assembly (which NM cable is) as though it were a circular wire with the same diameter as the _largest_ cross section of the cable. This means that something like NM fills a conduit pretty darn quickly.

Because of this, I do not belive that you could pull the extra #12 in the same conduit with the NM. If you were physically able to pull the extra conductor into the conduit, I do not believe that this would meet code. However most of the work that you did is not in the NM cable itself, but in the conduit, cutting it and fitting it and putting it up. And I believe that you will be able to use the conduit. What I believe you are going to have to do is pull out the NM cable, and then get individual wires of the appropriate color and size, and pull these into the conduit.

I will need John or someone else to check my figures, but I believe that you can have up to 8 12 gage THHN wires in 1/2" PVC conduit. At most you will need 5 wires.

You will need to buy green, white, black, red, and one other color.

In the previous instructions where I would say things like 'join red from S1 to red from R2', in other words every joint that simply carried the wire in one side and out the other side, you can simply pull the wire through without making a joint.

You can use _stranded_ wire for this; it is much easier to pull, but somewhat harder to terminate; if you decide to use stranded wire, then you should practise making splices prior to putting them in your walls. If you decide to use stranded wire, you may find that it is worth investing in higher quality 'back wire' receptacles and switches. These are not the cheap devices that you push a wire into and a spring holds it, but instead rather more expensive devices ($3 -$12 for a simple duplex receptacle) where you push the wires into holes in the back, and then tighten the screw, which squeezes a pressure plate against the wire. (Hmm, I see from another note that you used commercial duty receptacles; these quite likely have the backwire option.)

The next thing that you will need to double check is 'box fill'. These rules basically talk about how many wires you can pull into a box to connect to things. For 12ga wire, each circuit conductor entering the box counts as 1 'unit' (this means that if you have a black wire coming in from one box, and a black wire coming in from another box, and they are spliced together, then count 2 units), any devices in the box (receptacles, switches, etc) count as 2 units, _all_ of the ground wires count as a single unit, and if you have wire clamps inside the box they count as 1 unit. Add up all the units, multiply by 2.25 and compare to the size of the box in cubic inches. The box where you have the power feed coming in is IMHO the one that is at risk for being overfilled.

Finally, it sounds to me like you intend to do this job 'right', investing in conduit, commercial wire devices, etc. It sounds like you've made a couple of minor mistakes, but nothing that you can't fix. I'd suggest taking a breather and reading a couple of wiring books just to double check things. Remember that the advice you get on the internet is worth what you pay for it

-Jon
 
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Old 02-26-04, 12:02 PM
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Oh, one last note: if you are pulling wire in conduit, you don't have to mess with recoding white wire as black; you just pull a suitable color wire.

-Jon
 
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Old 02-26-04, 12:17 PM
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You do not have to use 20 amp rated switches or 20 amp rated receptacles just because it is a 20 amp circuit.
 
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Old 02-26-04, 12:37 PM
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I think that this might be one of those instances were a 20A rated switch would be required. And if a careful read of code would suggest that the 20A switch were not required, then I would respond that 'code is a minimum standard for safety', and that in this case, in my own home _I_ personally would use a 20A rated switch.

Since the switch is controlling a number of receptacles, the load served by the switch is not well defined, and limited only by the circuit breaker. In this case, I believe that at the very least it would be a good idea that the switch be rated for the full 20A.

If the switch were controlling a set of light fixtures, then I agree a 20A switch would neither be required not a benefit; simply a switch with high enough current rating for the lights being served. If we know with certainty that _only_ light fixtures will be plugged into these receptacles, then we could again depend upon a lower rated switch, if only because someone, someday will plug a table saw or electric heater into one of these receptacles.

-Jon
 
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Old 02-26-04, 12:56 PM
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I agree with Racraft 20a switches are not required,but I do agree with winnie because there is a potential of high useage spec grade devices would be the way to go. I also hope that the 1st receptacle in the run is a GFCI,or use a GFCI breaker.As for conduit fill: 1/2" allows for 9 type THHN #12.
 
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Old 02-27-04, 06:48 AM
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2002 NEC:

404.14 Rating and Use of Snap Switches. Snap switches shall be used within their ratings and as indicated in 404.14(A) through (D).

only (A) applicable

(A) Alternating Current General-Use Snap Switch. A form of general-use snap switch suitable only for use on ac circuits for controlling the following:

(1) Resistive and inductive loads, including electric-discharge lamps, not exceeding the ampere rating of the switch at the voltage involved
(2) Tungsten-filament lamp loads not exceeding the ampere rating of the switch at 120 volts
(3) Motor loads not exceeding 80 percent of the ampere rating of the switch at its rated voltage

I think (3) would require at least a 20 amp switch since a 15 amp switch would be limited to 12 amps. Using this switch to routinely turn off a 2 or more horsepower air compressor plus other equipment in a garage workshop (which is what I am assuming ccsm is trying to do) would certainly be exceeding its capacity.
 
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Old 02-27-04, 08:02 AM
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20 amp switches are nor required by code for this setup. Period.

However, they would be a good idea if the intended use is to control a load of greater than 15 amps. I would certainly use 20 amp switches in this situation, probably without respect to the intended load.
 
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Old 02-27-04, 09:01 AM
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True. The code doesn't require a 20 amp switch in this situation. As a matter of fact, it doesn't require a 15 amp switch either. Or a 10 amp switch.
 
 

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