Adding a neutral wire to this old house switchbox?

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  #1  
Old 10-04-07, 06:42 AM
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Adding a neutral wire to this old house switchbox?

Fishing question here for any experienced electricians:
I need to add a neutral wire to an existing switchbox in an older home. I don't want to run a single, insulated, unprotected white wire through my attic because that is probably against code and not safe, anyway.
Options I see:
1) Pull out the old 2-conductor cable and use that to pull in a new 3-wire cable with neutral going back to the breaker panel. However, this will be a problem if the old cable is stapled to the studs.
2) Run conduit through the attic and wall to the existing switchbox and put the neutral wire in that conduit (wow, that seems like overkill!).

Either way, I'm guessing I'll have to replace the switchbox itself with a new box or I may have trouble re-attaching the old box to the wall. Yes?

Any other ideas out there about running the wire/cable or reusing vs. replacing the box?

Thanks,
Joel
 

Last edited by Joel777; 10-04-07 at 06:44 AM. Reason: added more thoughts
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  #2  
Old 10-04-07, 07:53 AM
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Please provide a better picture of your situation. Why is there no neutral wire already on this circuit?

Your only choice is to completely replace the cable. You cannot run a neutral wire separate from the hot wire. Just abandon the existing cable and add a new cable.

As for replacing the box, you can with a little trial and error, fish a wire into an existing box.
 
  #3  
Old 10-04-07, 08:49 AM
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Add Neutral to Service Panel

Joel,

Why do you believe that you need to run a "Neutral" into the Service Panel?

Have you removed the service panel cover? If you have, depending on the age of the panel and design, you should see the two line Ins from the power company. Look to the right of the main panel, you should see the grounding bus, Is there a wire from the service in cable to the grounding bus?

Over to the left, should be the Neutral bus bar, is it there?

My suggestion is to get professional help to do this task. I'm not an electrician and I am mildly acquainted with the NEC Code you if you decide to go ahead and do this, you will be putting your hands in what I call the Kill Zone. There is no mercy with electricity!

First, the Neutral you need to add must come from the Power Company's Service In cable. Which means you are going to have to contact the Power Company to see if they are willing to bring that service to you.

You will need to pull a permit to do the work. You may have to replace the panel box and increase you Line In Amperage.

Next, you will have to handle lie unprotected power lines, so if you don't mind adding me to your will as sole beneficiary
of your estate we can proceed.

I'm very serious here, please call an electrician and get several estimates.
 
  #4  
Old 10-04-07, 09:18 AM
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Apparantly you need to route a conductor from Point "A" to Point "B".

Why is this additional conductor needed ?

Where will it terminate at Point "A"

Where will it terminate on Point "B" ?

Where is Point "B" located ? 1st floor ? 2nd floor?

Where is Point "A" located ?

Installing additional conductors in a "finished" house is best effected by routing a cable inside walls ( a "vertical" direction) and above ceilings ( a "horizontal" direction ).

What is involved , from a "structural" viewpoint, in running from Point "A" to Point "B" ? Ex: Along exposed joists in the basement, then running "vertically" inside a partition to the attic, then "horizontally" across the attic to ---- ?
 
  #5  
Old 10-04-07, 09:50 AM
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Doesn't anyone else think the original poster might mean 'ground' instead of 'neutral?'

Joel, are you wanting to add the third, bare wire, to the circuit?
 
  #6  
Old 10-04-07, 10:20 AM
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Originally Posted by mdtaylor View Post
Doesn't anyone else think the original poster might mean 'ground' instead of 'neutral?'

Joel, are you wanting to add the third, bare wire, to the circuit?
Since he said "switch box" I was thinking a switch loop and he wanted to add a receptacle or control (timer?) needing a neutral but I think you may have the right idea.
 
  #7  
Old 10-04-07, 09:52 PM
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Gone Fishing

Thank you, folks, for the great responses. Apologies, but I originally gave you just enough info to be confusing, However, if I mentioned that I'm adding a neutral wire so my new X10 home automation fan dimmer control will work, someone may have flamed me and sent me to the home automation forum with what really is a basic wiring question: "How do I add (and fish) in a neutral wire to an existing switchbox and do it safely and code-legal?" I think I've gleaned my answer from your comments and so I'll probaly run a new 12/3 cable from switchbox to fan J-box (my pt. A to pt. B) and abandon the old cable. I can pick up the neutral there, of course, rather than going back to the main panel (that was my bad assumption originally!).

Thanks again to all who responded.

Gone fishing,
Joel
 
  #8  
Old 10-05-07, 05:19 AM
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Joel,

Thanks for the clarification. Picking up the neutral at the fixture box (where the switch loop originated from) is the only place you can pick up the neutral. You cannot simply grab a neutral from any junction box nor can you run a neutral from the main panel.

In this case, replacing the 12-2 cable with 12-3 cable is the solution.
 
  #9  
Old 10-05-07, 10:38 AM
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Presumption---- That the ceiling outlet-box where the fan is connected is accesible from the attic , and you will run a cable from this box and across the ceiling joists ( "horizontal" direction" to the point where the cable will extend down inside the partition "(vertical" direction ) to the switch outlet-box.

IF-IF -- there is no problem in inserting a 3-wire cable in both boxes while leaving the existing 2-wire cable in place in both boxes , consider this connection---

At the ceiling outlet-box , connect the 2-wire cable from the switch to the 2 wires of the "Feed-In" pair. At the switch , the 2 wires from the ceiling-box are now a "Feed-In" pair , 120 volts across the Black & White wires.

The new 3-wire cable between the switch outlet-box and the celing outlet box now can be connected as two seperate "switch-legs" to the ceiling box, which allows two seperate control-functions at the switch-box.

Provides a degree of "flexibility"- never hurts to have a "spare" wire available for future use.
 
  #10  
Old 12-09-12, 07:14 AM
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Knob & Tube

You mentioned having an old house so more than likely you have knob and tube. In knob and tube, the neutral and hot are two separate lines and everything was wired parallel, meaning that that one or more of the two conductors runs through your house and is spliced near every fixture. In a light switch, they spliced the neutral from the main kt line and went straight to the light while the hot wire was spliced and went to the switch box first and then another single kt line (switch leg) went to the light. My house is the same way although I'm in the process of replacing it all. Knob and tube is very brittle and anytime you touch it, other than replacing a fixture or outlet, you have to replace it or it is considered unsafe.
 
  #11  
Old 12-09-12, 08:53 AM
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Ajb2312 Welcome to the forums. You have responded to a five year old post from a user that has not been on the board since March, 08. Always glad for help but if you want to help please help on more recent questions unless you see something fundamentally wrong in an old post.

Thanks.
Ray
 
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