Reverse Feed A Broken Neutral - K & T Wiring

mdcorreia

Years ago, in a home, I found that the neutral was broken (lights not working) but could not find where because of open knob & tube splices (sodered) anywhere inside the ceiling. The home was going to be rewired soon, however I wanted to restore power for a while.
What I did was to take a new cable from the panel to an END OUTLET of that same circuit and connect ONLY the new neutral. All worked fine! Now the circuit had 2 neutrals one at each end!

(My experience is that the neutral is always the one that fails in old wiring, in overloaded circuits, in poor connections at a jb etc. and never found anyone who can explain why?)

If it was the HOT that failed, I would probably refeed that circuit in reverse to an end device outlet while insuring that the new cable was fed from a first device outlet area etc. This way, I would be sure that I would be using the same PHASE and the same circuit.

Any response would be appreciated - Thanks in advance - mdcorreia

mdshunk

All conductors of the same circuit must be contained in the same cable or raceway. What you did, while it solved the problem, was a technical violation.

mdcorreia

Of course it was a violation. That is why I cited the 2nd suggestion which is not. The code is only a good guide for safety but, like the bible, has many interpretations and I could find a few that would stun some!. A switch leg has not all conductors of a circuit! If one has the right device to test it there is a lot of induction!

RobertWilber

Article 300.20(A) would suggest that the purpose is to prevent inductive heating of the enclosure and/or raceway. Since a switchleg balances the inductance, there is no need for the neutral to accompany the ungrounded conductors. This is the reason you can't use 2 conductor cable for a three way and pick up the neutral somewhere else.

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Philadelphia electrician