Lighting/receptacle circuit


Old 12-16-00, 11:57 AM
Brent Turner
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I have a 3 way switch that I want to continue a receptacle circuit off of. The 3 way switch is set up with the light in the middle of the two switches. I want to run the circuit of off the first switch, but I am unsure how to continue. One other question please, how does a 120 volt branch circuit differ from a 120 volt isolated ground circuit? Thanks for any help.

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Old 12-16-00, 02:04 PM
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I'm not an electrician, but normally lighting circuits are separate from outlet circuits.
For instance, a lighting circuit might be on a 15 amp breaker and smaller 14 gauge wire circuit (which your's may be), and an outlet circuit should be on a 20 amp breaker with 12 gauge wiring.
Sprky or one of the other pro electricians in here can answer your technical and code questions (I can't), but I don't think that I would do what you plan to do.
In any case, Good Luck!
Old 12-16-00, 02:16 PM
Brent Turner
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This is on a 15 amp breaker with 14/2 wire to the receptacles from the box. The cable on the three way switch is 14/3. I currently have 4 receptacles and a ceiling light on this circuit.
Old 12-16-00, 05:10 PM
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Tapping power from a switch for an outlet is "iffy" at best. With some switches it can be done -- with others it cannot.

The first thing you must determine is whether you have both a permanent hot wire in the switch box. Use a voltmeter and make sure this wire has power no matter which of the four positions of the two switches.

Second you must determine whether you have a neutral wire in the box. Turn off the power. Use an ohmmeter. Find a white wire with zero ohms to the ground wire.

Unless you have both, you cannot do this. Many three-way switch boxes have neither!!!

And OldGuy, your presumption of lights and outlets being on separate circuits is going too far. There are hundreds of millions of outlets on 15-amp 14 gauge circuits, and hundreds of millions of circuits containing both lights and outlets.
Old 12-17-00, 05:17 AM
Brent Turner
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Thanks for your reply. I just ran this circuit from the box and it goes like this. Outlet, outlet, outlet, outlet,
3 way switch, light, three way switch. I would like to continue the circuit at the first switch box, but the last outlet is only couple feet away. If its not possible to continue the circuit at the switch box I will go back to the last outlet. I just had the wire already pulled through to the switch box, I can always go back and pull some more wire.
Old 12-17-00, 10:13 AM
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Brent, thanks for the clarification. Yes, you can certainly continue this circuit from the first switch box. No problem at all. Just connect the continuation cable to the black and white wires coming in from the nearby outlet. Be sure to use a pigtail to connect to the switch, rather than try to put two wires under one screw or rather than try to use both a screw and a push-in connection.

I'm sure you already know this, but you'll never be able to add anything to the second 3-way switch box (except another switch for this light).

Have fun!
Old 12-17-00, 01:34 PM
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Looks like John Nelson has already got you fille in on your wiring design, but you seemed to have a second question still unanswered.

You asked;
One other question please, how does a 120 volt branch circuit differ from a 120 volt isolated ground circuit? Thanks for any help.

An isolated grounding receptacle has a redundant equipment ground to it direct from the grounding source.

You would use an isolated grouding recepatcle that has no contact between the green ground screw of the receptacle and the yoke of the receptacle that supports the receptacle. The bare wire of the Romex serving this dedicated receptacle would connect to the steel box and the green screw connected to the mounting yoke only. Then a green insulated equipment grounding conductor would also be run from that isolated grounding receptacle through the service panel without making contact within that service panel serving that isolated grounding receptacle then continue to run non stop to the grounding source [ususally the ground rod] This isolated grounding wire would then be connected to the second green grounding screw of the isolated grounding recepatcle that serves just the grounding hole of that isolated grounding receptacle. Remember these two equipment grounding conductors do not touch in the receptacle or even in the main panel.

This isolated grounding receptacle is used for extra protection where needed for sensitive and or vital electronic equipment.

This redundant grounding is also commonly required in hospitals and the like for the same vital use reasoning.

Hope this helps


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