adding three way switch to two lights

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  #1  
Old 12-28-06, 07:45 PM
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adding three way switch to two lights

i want to add a switch at the bottom of the basement stairs to control two prexisting lights (one at the top and one at the bottom of the stairs ) which are currently controlled by the switch at the top of the stairs and be able to control both lights at either switch. i have a good diagram for the wiring of a two three way switches with one light in the middle. does adding the second light complicate the wiring in a way i have not considered ?

for the second light should i power it by the black and white of the first light?
 
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  #2  
Old 12-28-06, 08:54 PM
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If the first switch and the two lights are existing and work properly, then you need to add a cable from the first switch to the second. The cable needs to be 14-3 or 12-3, depending on whether the circuit is 15 amp or 20 amp.
 
  #3  
Old 12-29-06, 11:00 PM
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Watch your wire count.

If the box were the existing switch is now is single gang then you are likely to go over it's allowable wire capacity unless it is a deep plastic box. What size is the present box? How many wires are in it now? What wiring method was used for the existing wiring? Can you fish the new cable you will need up to that box? With the answers to those questions we can be more help.
 
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Old 12-30-06, 12:32 PM
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there are many ways to wire a three way switch and the only real necessity is that the cable b/w the two switch boxes be 12/3/wg or 14/3/wg. (as racraft stated)

As hrnetd stated if you already have three wires in a single gang box then you are going to go over code allowances by adding a fourth. What you may be able to do is re-route the switch leg going to the first light to the box at the bottom of the stairs and then run your 14-12/3/wg cable b/w the two boxes. (of course this is assuming that you don't have a switch loop in the fixtures) Which we will assume for now being as we're not sure whats in the actual switch box. Post back if you need some more info. AMP
 
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Old 01-03-07, 08:08 PM
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thanks for the replies,

at the top of the stairs there is a single gang box with a switch with a black and white wire (12/2). it is a small metal box maybe 18 cu in.

the light at the top of the stairs has a black and white wire .

the light at the bottom of the stairs is pigtailed to an incoming line and outgoing line to the light at the top of the stairs.

all connections are black to black and white to white.

i assume there must be a junction box somewhere (?attic) where the switch or bottom line in are powered and that the top switch should properly be a black wire and a white wire taped black.

i hope this is not confusing, i am not that great with the terminology
 
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Old 01-03-07, 08:13 PM
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If the first switch and the two lights are existing and work properly, then you need to add a cable from the first switch to the second. The cable needs to be 12-3.
 
  #7  
Old 01-04-07, 07:55 PM
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sorry if i seem dense racraft , i think i see what you are saying in that the proper connection between the two lights and switch are already in place. i will put in a deeper box at the first switch and run the 12/3 from the first switch to the new second switch.

if i don't need to alter the connections at the lights what will be the connections for the incoming line and 12/3 to the three way switches?
 
  #8  
Old 01-04-07, 08:05 PM
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At the existing switch. Take the two wires off the the switch. Leave all the rest the same.
Connect one wire to the common screw of you three way switch.
Connect the other wire to the black wire of your new cable.
Connect the red and white from the new cable to the traveler screws of the three way.

At the new switch location.
Connect the black wire to the common screw.
Connect the red and white to the traveler screws.

Common screw is the black one or marked common.

Also connect all the ground wires together and to the green screw of the switch if it has one.
 
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