Here a problem where the "obvious" solution scares me, need some advice on how to best proceed. My home (built 1920 with knob and tube type wiring) has been upgraded over the years by prior owners, but in many place still has active current in the old wires, in other places it is spliced into a modern wiring. A modern (correctly wired) 100 amp service panel is supported by an old fashion subsidy panel for the 2nd floor that seems to be an old (2 wire (no ground)) design where someone has spiced in 3 to 2 fashion and tied the neutral and ground wires to the same bus. This deeply offends my sensibilities, but I have never removed it (and we did not discover it before we bought the home).

Today I noticed two dead outlets in a room that has been "upgraded" to modern 3-prong plugs. The wiring appearing at the outlet is modem. Tracing back to the service panel is not possible without destruction of walls. Upon investigation with a VM, I have 75v between black and white, and 120V between black and ground. Yep you guessed it, it appears that the bare ground wire is being used as the active return rather then the neutral. At this point God alone (and perhaps the idiot builder) knows where the neutral connects, if at all.

I could perhaps "solve" this problem by connecting the ground and neutral lines (as have already been done in other places in this home), but my first fundamental question is should such a thing ever be considered proper to do? Second, how does one document such an unorthodox condition for others? I know a much better solution is to run my own wire from the panel and sikp all this suspect stuff.

The only place, within a residence, where Neutral and ground should meet up is the main panel box. Neutral and Ground are bonded together there.

To answer your question, no, you should not use the bare ground wire as the Neutral return.

However, the Neutral (White or Gray) can be used as an ungrounded (Hot) conductor. When that is done, the White or Gray conductor must be permanently re-identified, For example, use a Black Permanent Marker to place a band of Black around a White or Gray insulation to flag the conductor as a hot conductor. This should be done at both ends of the conductor.

There are common places where this is done, switch loops. The white (flagged) conductor is routed from the Hot supply in the ceiling to the IN side of a wall switch. Then a black returns from a switch to the light fixture. It is against code to use the White conductor as the return conductor. The return conductor must be black, red, blue. Never White, gray or green!

Also if you need a 240 VAC line, you can use Black as one hot side and a re-identified white as another hot with bare or green as the ground wire.

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Originally Posted by donf

The only place, within a residence, where Neutral and ground should meet up is the main panel box. Neutral and Ground are bonded together there.

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I agree and understand what you are saying for the main panel service box (and for the most part in this home that is where they are tied off together). Regarding my current problems, I will have the buzz out the line and track down which "white wire" is floating on the service bar. I have the tools, but it would have been nice if the last guy had documented the pannel.

Is this ever allowed in a sub panel? Or anywhere else for that mater according to code? It looks to me like it is occurring in odd hidden places in the home where the romex is spliced into the old 2-wire knob and tube lines. I have yet to see it actually at an outlet, but found it in the attic and under the stairs, etc.

Bump

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Originally Posted by DC Kelley

Is this ever allowed in a sub panel? Or anywhere else for that mater according to code? It looks to me like it is occurring in odd hidden places in the home where the romex is spliced into the old 2-wire knob and tube lines. I have yet to see it actually at an outlet, but found it in the attic and under the stairs, etc.

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Solved the initial problem, bad connection at the bus par in the service panel. But the above issue remain where the original 2-wire knob-tube style is tied to the new neutral and ground at a some odd points along the run (and black to the other side). I need to learn if this is a liability that needs to be addressed, or just an accepted practice in such an old home.

What you have is a loose connection at the neutral or a break in the neutral, they are most likely not using the bare as the neutral, If you are showing any voltage at all on the natural than mostly likely it is a loose connection. You will always show full voltage between the hot and the ground. (Duh)

clintster, bear in mind what we have here is a five year old thread. It's probably safe to say the issue has been resolved.