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-   -   Neutral and Hot swapped? (http://www.diychatroom.com/f18/neutral-hot-swapped-158894/)

stevefrench 10-03-2012 10:26 PM

Neutral and Hot swapped?
 
I am in the middle of a deep investigation into an old circuit in my house that is still wired up with K&T and has had a lot of work done by the previous owner which has not been done well. I have been tracing back all of the wires from the breaker box and in the attic and have come across something that I'm a bit confused about.

This circuit is fed into the attic from the breaker box with a 12/2 romex cable. The white wire is connected to the ground/neutral bus in the breaker box. the black wire to the breaker. In the attic, the romex comes up into a junction box, where it is spliced and connected to an outlet directly below, and then to a long K&T run. At this junction box, the white is neutral and the black is hot.

In the middle of the K&T run, between the first j-box and the third, there is a splice to another junction box. White to neutral, black to hot. This feeds an outlet and light directly below.

This long K&T run continues to another junction box, where the neutral is now spliced to 2 black wires and the hot is spliced to 2 white wires on 2 separate romex cables. One romex cable feeds a room below which has a light switch, light and an outlet, and another feeds a switch controlling a ceiling fan. There is then another romex cable coming out of that switch going to the fan.

It appears as though in these rooms everything is hooked up correctly. I put a plug tester in the outlet and it is not reading a reverse of hot and neutral. I pulled apart the outlets and switches and everything appears to be connected as it should be. black to brass, white to silver terminals.

Can anyone shed any light on this situation? Should I swap the hot and neutral wires at the junction box in question in the attic? Is this something I even need to be concerned about? I hope I have been clear enough but if not let me know what info I can give to provide any more clarity.

PS I have a voltage detector and it is detecting voltage on both the neutral and hot K&T even when everything on the circuit is turned off.

daveb1 10-04-2012 07:07 AM

What type of tester are you using, a meter or a non-contact tester? The non-contacts and digital meters will pick up almost any type of voltage, including what might be induced from another circuit. Also be aware that K&T often used a switched neutral.

joed 10-04-2012 07:26 AM

The knob and tube colours are messed up or crossed somewhere.

stevefrench 10-04-2012 08:59 AM

Hi Dave - I've used 3 types of testers. A non contact voltage detector that you just touch to the wire. A digital multimeter. And a Plug tester. I did read a bit on switched neutral after I posted and it seems like that's what is going on here, since the neutral K&T is spliced to the black wires of the romex in the attic, and in the switch box the black wire is what's being switched. What I'm confused about is that if this is the case, shouldn't the plug tester show reversed neutral/hot when I plug it into the outlet?

Subsequent question - when I do bring new romex to this j-box, it sounds as though if I wire it hot to hot, neutral to neutral, everything should be fine and this portion of the circuit should now switch hot instead of neutral. Does that sound right?

Joed - that is exactly what I thought as well, but I have traced every inch of the K&T back from this j-box to the previous ones and it is not crossed anywhere.

joed 10-04-2012 10:49 AM

You should just replace the K&T with NM cable. It sounds like it is readily accessible to run the new cable.

dmxtothemax 10-04-2012 10:33 PM

1 Attachment(s)
A lot of high input impedance type testers can give false readings,
under some circumstances.

If you know which pin is suppossed to be hot,
Then you can test, using a test lamp.
Do not use a digital type meter,
the only option is a anologue type low impedance ac volt meter
such as - Attachment 58306

Connect one side of a test lamp to the hot pin and the other
side via an extention lead to your neutral bar.

If this lights up correctily then its surely connectted right.
Test all outlets like this.

Be really careful !
If not 100% confident then do not do it !
Call an electricain instead !


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