Strange 2 hot wires

Reply

  #1  
Old 08-20-09, 07:49 AM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
Strange 2 hot wires

I just replaced an outlet with a GFCI. The outlet is on a 20-amp circuit that is essentially K&T (at least, the hot and neutrals are coming in on different cables, entering / leaving the box through different knockouts...).
The hot cable was strange. It actually contained two insulated wires, like an early Romex without the ground wire. Both wires were hot, and on the same circuit, and attached to different screws on the outlet although the brass tab had absolutely not been removed. I didn't have a voltmeter to test if there was a voltage between the two hots, but given how they were wired to the outlet, they must be in phase.
Anyway, I capped off one of the hots, tucked it into the box, and installed the new GFCI which seems to work.

But I can't quite let go of the strangeness. Assuming the old wires are 12 AWG, and that I've properly capped off the unused hot, I would think it should be safe. But I don't definitively now the gauge of the old wire. Was it ever professional practice to run two smaller (e.g. 14 AWG) wires in parallel rather than a larger gauge (I realize that question may not even make sense)? Any other thoughts / ideas / concerns?
 
Sponsored Links
  #2  
Old 08-20-09, 09:18 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Fuse box or breaker box. If breaker box is there an older box used for connections only that could be a gutted fuse box.?
 
  #3  
Old 08-20-09, 09:26 AM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
Breaker box. There are two breaker panels in the house; this one connects to what I think is the older one. Could be a gutted fuse box - I wouldn't know how to tell. But this breaker box looks definitely looks dated compared to the other, and also given the rooms it services, is probably the original panel. If there is a no-longer-used fuse box, I've never seen it.
 
  #4  
Old 08-20-09, 10:48 AM
Member
Join Date: Jun 2008
Location: VA.
Posts: 813
Received 1 Vote on 1 Post
Were you using a non-contact tester to see this happening?

You most likely have some receptacles or lighting that's wired reversed polarity if I'm reading you right.

I think if you check the voltage there will be, for example, 80 volts on the hot and 40 on the neutral. Either that or a neutral is being shared with another circuit somewhere.
 
  #5  
Old 08-20-09, 11:25 AM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
I did use a non-contact tester. I have a voltmeter that I haven't used before....
If indeed I see 80 v on one and 40v on another (e.g.), would that indicate that both wires should feed the outlet in parallel? What is the impact of using just one? (The outlet does work with a vacuum and drill running simultaneously, the extent of my testing)
 
  #6  
Old 08-20-09, 11:37 AM
Member
Join Date: Jun 2008
Location: VA.
Posts: 813
Received 1 Vote on 1 Post
You could get a receptacle tester that has the 3 lights on it and try to find the culprit receptacle(s) and fix the wiring.

Did you have 2 prong receptacles that were replaced with 3 prong? If so, I would look at those first. It may just be one that's messing the whole circuit up. With some K & T, it's difficult to tell which is hot and neutral so someone possibly just hooked one or some up wrong.
 
  #7  
Old 08-20-09, 12:25 PM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
I used the voltmeter and got a reading of 120v - right on the money. So whatever the voltage is on the wire I capped off (I did not pull out the outlet), the one I tapped into is at 120v.

Also, both of these hot wires are on this circuit. The wires are hot with the breaker on; no voltage with the breaker off. So I don't think that indicates that one of these is a neutral for another line (or else it would have stayed hot when I flipped off the breaker).
 
  #8  
Old 08-20-09, 02:04 PM
Member
Join Date: Jun 2008
Location: VA.
Posts: 813
Received 1 Vote on 1 Post
I think I may have misunderstood what you said. I was thinking when you said "both wires were hot" I thought you were getting a reading on the hot and neutral.

If you were just talking about both hots being hot even though it was disconnected, then that would mean that, that circuit was being "fed" from 2 different directions, so to speak.

Like a closed loop if you will.

Just cap them off as you did and you're good to go.
 
  #9  
Old 08-20-09, 08:54 PM
dougm's Avatar
Member
Join Date: Sep 2003
Location: The Colony, Texas
Posts: 917
Received 0 Votes on 0 Posts
Is there perhaps a wall switch somewhere in or near the room that doesn't do anything?

Doug M.
 
  #10  
Old 08-21-09, 06:06 AM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
There could be such a switch, but it is not nearby. If you trace the wire through the crawlspace (and remember, both hots are contained in the same romex-like sheathing), it is stapled to a joist out the bedroom, down the hall, and past where I can see it. I
 
  #11  
Old 08-21-09, 06:12 AM
Member
Join Date: Jun 2008
Location: VA.
Posts: 813
Received 1 Vote on 1 Post
What I meant by checking voltage on those 2 wires is each one to ground, not putting your meter on the 2.

I would think if it was a switch and wired to hot and neutral of the receptacle, it would have been a dead short.
 
  #12  
Old 08-21-09, 06:23 AM
Member
Thread Starter
Join Date: Aug 2009
Location: California
Posts: 25
Received 0 Votes on 0 Posts
Re the testing: Right, I understand. The non-contact tester found no current in the neutral, and voltmeter shows a reading of 120v between neutal and the hot powering the outlet.

If I had the capped off wire pulled out, I'd check the voltage between the two hots to prove it's zero. But given the way it was wired (to other screw on same receptacle with the brass tab intact), if there was a voltage of 240v between the two hots there would have been a fire long ago. So I'm pretty much presuming the two hots are in phase.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: