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Unintentional shared neutral - is it a problem? (Residential wiring)

Unintentional shared neutral - is it a problem? (Residential wiring)

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  #1  
Old 09-06-12, 06:00 PM
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Unintentional shared neutral - is it a problem? (Residential wiring)

I recently came across a questionable wiring issue on a project.

The home was remodeled about 5 years ago. The homeowner says a licensed electrician did the work.

The original setup was a single pole switch and a single ceiling fixture. The revised setup was a single ceiling fixture with two 3-way switches.

The original single pole switch was changed to a 3-way switch and the white wire from that switch to the light was re-purposed. The neutral that used to run from the single pole switch to the light was wired to be a traveler for the replacement 3-way switch (seems logical). A 14/2 romex cable was pulled from the light to the location of the new 3-way switch and was also wired as a traveler. The missing link is a neutral line for the fixture: A solitary neutral wire was connected from the light fixture to an unrelated light fixture about 10 feet away.

I follow the thought process and execution of the modification up to this point.

BUT, the borrowed neutral is on a different breaker than the hot and ground for the original switch. The two breakers are NOT ganged.

I found some threads on multiwire circuits, where sharing a neutral is intentional. But what about a situation like this? The house hasn't burned down and I assume the electrician knew what he was doing. But that little voice in my head is making me ask anyways.

It seems like an easy fix to run a new neutral connection from the light to a different light or junction box on the same circuit, but is it necessary?
 
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  #2  
Old 09-06-12, 06:11 PM
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A solitary neutral wire was connected from the light fixture to an unrelated light fixture about 10 feet away.
I'd like to see a picture of how this was done, it sounds like it has "CODE VIOLATION" written all over it. How was that single solitary neutral conductor run? A real licensed electrician should not have done this, but I have seen a lot of questionable things done by so called "Licensed Electricians".
 
  #3  
Old 09-06-12, 06:22 PM
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The original single pole switch was changed to a 3-way switch and the white wire from that switch to the light was re-purposed.
Any electrician should know that this would not be needed to be done. All that needed to be done is run 3 wires(in conduit or in a cable) to the new 3 way location; 2 travelers, and a hot or switch leg.

There always needs to be at least two wires grouped together.
 
  #4  
Old 09-06-12, 06:54 PM
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The single wire was not in conduit - it was literally just the white wire as a jumper.
 
  #5  
Old 09-06-12, 06:57 PM
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Makes sense.

But given what I have, is it safe to have that neutral shared on two circuits?
 
  #6  
Old 09-06-12, 07:04 PM
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That's not acceptable,the installer was supposed to run 14-3 to the light fixture from each switch location and mark the white wire as a traveler with black paint or tape.
 
  #7  
Old 09-06-12, 10:22 PM
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The original single pole switch was changed to a 3-way switch and the white wire from that switch to the light was re-purposed. The neutral that used to run from the single pole switch to the light was wired to be a traveler for the replacement 3-way switch (seems logical). A 14/2 romex cable was pulled from the light to the location of the new 3-way switch and was also wired as a traveler... I follow the thought process and execution of the modification up to this point.
I don't. A 3-way system requires 3 current-carrying conductors.

Regardless, this:
A solitary neutral wire was connected from the light fixture to an unrelated light fixture about 10 feet away... BUT, the borrowed neutral is on a different breaker than the hot and ground for the original switch. The two breakers are NOT ganged.
is a code violation. A neutral load may not be added to a different circuit, as defined by the hot wires, in order to prevent over-heating.

And this:
run a new neutral connection from the light to a different light or junction box on the same circuit
is also a code violation. The neutral for a given circuit must be contained in the same raceway as the ungrounded conductor - cable or conduit - for its circuit.
 

Last edited by Nashkat1; 09-07-12 at 09:57 AM. Reason: To remove non-beneficial information.
  #8  
Old 09-07-12, 06:19 AM
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Thanks for the crystal clear response. Will revise the circuit accordingly.
 
  #9  
Old 09-07-12, 09:05 AM
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You're welcome. Reading back through my earlier post, I think I was clear about the code violations associated with running a separate neutral. I was not as clear about the best way to bring the system into compliance, though. Here's the straightforward way to do that, given that there is already a 14-2 between the second switch box and the ceiling box:

Run new 14-3 between the two switch boxes.

In the original switch box, the one with the panel feed and the original load wiring, connect the hot wire from the panel to the point or common terminal on the 3-way switch. Splice the white wire from the panel to the white wire in the 14-3. Connect the red and black wires in the 14-3 to the two traveler terminals on the switch. Abandon the 14-2 from this box to the ceiling.

In the second switch box, splice the two white wires together. Connect the red and black wires in the 14-3 to the two traveler terminals on the switch. Connect the hot wire from the 14-2 to the point or common terminal on the 3-way switch.

Connect the light fixture to the 14-2 from the second switch box. Abandon the 14-2 from this outlet to the first switch box.

This puts all conductors for one circuit in raceways together, puts this light on the neutral for its circuit, and puts a neutral in each switch box, as required by the 2011 NEC.
 
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