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Old 12-06-2007, 11:11 AM   #1
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2 switches - 14/3 cable


I have prewired a bedroom for a ceiling fan, using 14/3 cable from the box to the ceiling box. The electrical box has 12/2 coming in, and 14/3 going out.
I don't yet want to use a fan, and have purchased a flush-mount light. However, because the electrical box is 2-gang I would like to install both switches at this time. I imagine the best way to cable this is to use the black from the 12/2 and pigtail it with 2 more connections. Then use the red, and black from the 14/3 for the connection. Then tie off the nuetrals (whites) with a wire nut.

I then hooked the red (traveler) to the black (of the fixture) and then put a wire nut on the whites & grounds.

I have this scenario is two rooms; one with 14/2 and 14/3 in a box, and one with 12/2 and 14/3 in a box (as described above).

My questions are:

1) When I turn on the switch with the red and the black pigtail the light comes on, but there is also power on the black line of the 14/3 even when the switch that the black 14/3 is terminated on is turned off.

2) I was able to get the fixture to work with the 14/3 & 14/2 combination, but not the 12/2 and 14/3 combination. Is there a rule against using the 12/2 as incoming power and then using the 14/3 to go to the fixture?

Sorry for the long post, I know it might be confusing, but any help would be appreciated.

Scott

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Old 12-06-2007, 11:25 AM   #2
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2 switches - 14/3 cable


scott,

first, you have to breaker the circuit for the SMALLEST wire size on the cct, this case 14AWG=15AMP cct. it is not good practice to mix wire sizes though.


you have 12-2 incoming to the box. 14-3 leaving.

incoming 12-2 black pigtailed into 2 - 1 going to a screw on each switch.

white from both wirenutted

incoming ground wirenutted with outgoing ground, and pigtailed into 2 - 1 to each switch

outgoing 14-3... black to 1 switch for your light, red capped off in wall box until you hook up the fan.

cap off red wire in ceiling box.

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Old 12-06-2007, 11:40 AM   #3
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2 switches - 14/3 cable


Richard,

Thanks for your response. I was afraid you were going to say that....mixing wires. The 12/2 is on a 20 AMP, as it was used on an existing double-pole breaker. The panel at this point is full. If you say don't use this scenario (mixed wires) and to get a sub-panel I'm fine with that...I can higher a licensed electrician. However, the smallest wire on the cct would be the wire of the fixture, correct? And I know for a fact that it's less than 14.

Your help is appreciated!
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Old 12-06-2007, 01:02 PM   #4
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2 switches - 14/3 cable


As mentioned the 14/3 requires a 15 amp breaker be installed in place of the existing 20 amp breaker. Try to pull a new 12/3 for your two rooms. this is how your wiring should look you can use either the switched black or the switched red for your new light.
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2 switches - 14/3 cable-ceiling-fan.jpg  

Last edited by Stubbie; 12-06-2007 at 02:36 PM.
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Old 12-06-2007, 01:16 PM   #5
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2 switches - 14/3 cable


Stubbie,

At this point the sheetrock is already in place, and I don't think replacing the 14/3 would be very easy. Would it be easier to have a sub-panel installed and move this onto a 15amp circuit?
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Old 12-06-2007, 01:22 PM   #6
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2 switches - 14/3 cable


Stubbie,

One more quick question:

I don't understand in the schematic why the switched red would still be hot when the switch is turned off. If the switch on the black is on, and the switch on the red is off - why would there still be current on the red wire?
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Old 12-06-2007, 02:31 PM   #7
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2 switches - 14/3 cable


I'm not sure I understand.... in the schematic with the switches off both the red and back to the light are not powered. I see I made a mistake though that should be 12/3 not 12/2 I'll fix it in a bit. The switches are neither off or on as far as position in the diagram I just drew some switches..... you just turn them on or off.
Are you saying that your wiring has the red still Hot or are you talking about the diagram?
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Old 12-06-2007, 02:33 PM   #8
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2 switches - 14/3 cable


Quote:
Originally Posted by scottmatt View Post
Richard,

Thanks for your response. I was afraid you were going to say that....mixing wires. The 12/2 is on a 20 AMP, as it was used on an existing double-pole breaker. The panel at this point is full. If you say don't use this scenario (mixed wires) and to get a sub-panel I'm fine with that...I can higher a licensed electrician. However, the smallest wire on the cct would be the wire of the fixture, correct? And I know for a fact that it's less than 14.

Your help is appreciated!
Fixture wires are an exception to the rule. It is because the fixture wire is contained within your box and no point of it leaves the box. Although there are limitations to how small a fixture wire can be based on the size of the conductor feeding it. Usually they take this in consideration in manufacturing of the light to make sure it is of adequate size. Technically by code your circuit should be protected by a 15 amp breaker, because a 14 guage wire is not rated for 20 amps. But a 12 guage wire is fine for 15 or 20 amps. Hope this helps
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Old 12-06-2007, 02:45 PM   #9
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2 switches - 14/3 cable


Scott

The breaker protects the branch circuit wires (conductors). The branch circuit conductors end where they connect to a device or the fixture wires in your case. The fixture wire is not part of the concern of the person wiring the new light or the electrical code. The manufacturers use a much higher temperature insulation around the wires of the fixture, therefore they can carry more amps in a smaller wire.
I'm not sure you need a sub-panel you would still have to get wire to the switch box. Your panel may accept what is called a tandem breaker or some take slimline breakers. These are 2 single pole breakers that fit in one space of the panel or in other words if you have a full size breaker you can remove it and put in a tandem to give you say two 15 amp breakers in that space instead of one.

Last edited by Stubbie; 12-06-2007 at 02:50 PM.
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Old 12-06-2007, 02:51 PM   #10
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2 switches - 14/3 cable


Quote:
Originally Posted by Stubbie View Post
I'm not sure I understand.... in the schematic with the switches off both the red and back to the light are not powered. I see I made a mistake though that should be 12/3 not 12/2 I'll fix it in a bit. The switches are neither off or on as far as position in the diagram I just drew some switches..... you just turn them on or off.
Are you saying that your wiring has the red still Hot or are you talking about the diagram?

Sorry, I didn't mean your diagram - per say. When I previously wired it, I wired it as your diagram shows, the red wire on one switch and the black on another, with the power coming in via the 12/2 and pigtailed to the two switches. However, I don't understand why when the switch with the black wire (from the 14/3) is on, the red wire (caped off at the fixture) still tests as "hot" when I put a voltage detector up to it. Since the red wire is on it's own switch, shouldn't it be off when it's corresponding switch is off?

This is not what I'm seeing. If the red wire switch is off, and the black wire switch is on - I can detect voltage on the end fixture end of the red wire. Why would this be?
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Old 12-06-2007, 02:54 PM   #11
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2 switches - 14/3 cable


Quote:
Originally Posted by scottmatt View Post
Stubbie,

One more quick question:

I don't understand in the schematic why the switched red would still be hot when the switch is turned off. If the switch on the black is on, and the switch on the red is off - why would there still be current on the red wire?
Hey Scott,

Are you testing the red wire with a "non-contact" tester? In other words, one of those little testers that lights up or beeps when you hold it close to the wire? If so, it is likely that you are encountering phantom voltage. The red wire is inducing voltage due to the fact its all wrapped around the black wire in the cable assembly.

Andy

PS: Phantom voltage is harmless. It used to freak me out a little....but when you put a load on the wire ( I wrap my finger around the insulated part of the wire) the voltage magically disappears.

Andy
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Old 12-06-2007, 02:54 PM   #12
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2 switches - 14/3 cable


Quote:
Originally Posted by Stubbie View Post
Scott

The breaker protects the branch circuit wires (conductors). The branch circuit conductors end where they connect to a device or the fixture wires in your case. The fixture wire is not part of the concern of the person wiring the new light or the electrical code. The manufacturers use a much higher temperature insulation around the wires of the fixture, therefore they can carry more amps in a smaller wire.
I'm not sure you need a sub-panel you would still have to get wire to the switch box. Your panel may accept what is called a tandem breaker or some take slimline breakers. These are 2 single pole breakers that fit in one space of the panel or in other words if you have a full size breaker you can remove it and put in a tandem to give you say two 15 amp breakers in that space instead of one.
Thanks Stubbie. I'm currently usings a tandem breaker for this branch circuit. We have taken what was existing (for upstairs) and made all available slots in the panel tandem for the downstairs (total of 8 new circuits - 4 20AMP, 4 15AMP). I believe the reason this branch was put on a 20AMP is for the sake of teaming it with another 20AMP from another branch. So, at this point, I'm left with downgrading a different 20AMP branch, and then putting this one and the downgraded on a 15AMP or getting a sub-panel?
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Old 12-06-2007, 02:56 PM   #13
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2 switches - 14/3 cable


Are you using a non-contact tester like this------

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Old 12-06-2007, 02:57 PM   #14
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2 switches - 14/3 cable


Quote:
Originally Posted by Andy in ATL View Post
Hey Scott,

Are you testing the red wire with a "non-contact" tester? In other words, one of those little testers that lights up or beeps when you hold it close to the wire? If so, it is likely that you are encountering phantom voltage. The red wire is inducing voltage due to the fact its all wrapped around the black wire in the cable assembly.

Andy

PS: Phantom voltage is harmless. It used to freak me out a little....but when you put a load on the wire ( I wrap my finger around the insulated part of the wire) the voltage magically disappears.

Andy
Bingo! That's what it is.....(yes, that would be the voltage detector)

I even bent the red wire completely away from the black (on the ends that don't have the casing) to see if I was getting a bleed over from the "hot" black wire. But, this has got to be the case. It concerned me in the scenario stated above, as I didn't understand what the point of the switch was if there was still voltage in the line. I will give your test a shot.
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Old 12-06-2007, 03:00 PM   #15
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2 switches - 14/3 cable


Quote:
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Are you using a non-contact tester like this------

Similar, yes. I think it's a Greenlee. It looks like this:

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