Light switches in "L"-shaped hallway

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Thankfully, I have never seen any knob and tube wiring.
I did read that knob and tube does not always use standard switching so caution is advised.
{ This site says... http://advice.thisoldhouse.com/showthread.php?t (39
There are a few things you need to consider when dealing with knob & tube wiring. The first thing is they can be very brittle and the insulation can start falling off exposing bare conductors. The second thing to consider is how 3-way switches were once wired. At one time when houses were wired with knob & tube, they would feed the 3-way switches with a hot and neutral. They would then send a single conductor from the point screw of the switches to the light(s). The switched would either send up a neutral signal or a hot signal depending on the position of the switch. This is often called lazy susan switching. If the lazy susan wiring gets changed around on the 3-way switches you end up with a short circuit (hot to neutral short). Since it does not sound like you have this issue you probably don't have lazy susan wiring. }
Since I have never messed with any knob and tube I really can't tell you what would happen. I would not want to risk putting a direct short on brittle insulation.
One way you could tell if you do have a hot and a neutral at the 3-ways would be to turn the power off and disconnect both switches. Then with the power on, check between each wires of each switch. You should NOT have 120V between any of the wires. If you do, then you might have one of the above switching arrangements. (Stop here and post back)
If you don't have 120V between the wires, you could then go one step farther to make sure you do have travelers. Turn the power back off, and with a helper do a continuity check. The two wires that were not hot should go directly to the other switch. If this is the case then it is a safe bet that you do have a standard switching arrangement.
On Sat, 26 Jan 2008 16:00:22 -0500, "BETA-32"

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There weren't many codes when knob and tube wiring was installed. Generally if it hasn't been messed with it is probably safe since it's been in use for many years, but you do need to be aware and not overload things.
As for 'standard switching' the one thing I've seen when I've dealt with it is that they didn't always keep the hot and neutral together. That is, the hot might run thru the switch box and on to the light or whatever is controlled, whereas the neutral might come into the light from another direction.

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I've never heard of "lazy Susan" but it goes by many names, typically "Carter system, or lazy neutral", and although pretty much outlawed by the NEC in 1920, it was used for decades longer and not exclusive to K&T wiring. From my experience K&T wiring has held up better than anything in the industry until thermoplastic came on the market. It's demise came when circuits were required to be grounded. In switch boxes, it tends to be in excellent condition, but in ceiling outlets where light fixtures were in close proximity to it, it would bake the insulation causing it to crumble when moved. The rubber covered cloth conductors used in the forties and fifties were even worse in this situation

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Well, no luck for me. I must have a bigger problem than I realized. I did the steps below, but with the power ON, none of the wires are hot -- not hot when I put the tester from each wire to each other wire, and not hot when I put the tester from each wire to the metal switch boxes.
It hasn't worked since I bought the house a long time ago, so something else must be wrong somewhere. I have knob and tube wiring.

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Because knob and tube is not grounded, the wires might be hot and your don't have a tester that will sense it.
Try one of these. Test it by putting in in a known hot outlet before using.
http://homerenovations.about.com/od/electrical/p/voltagetester.htm
On Mon, 28 Jan 2008 18:14:45 -0500, "BETA-32"

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Thanks again. I tried that and it didn't work. I connected the wire to a metal cold water pipe near each of the switches and tried using that as the second wire for the test. So, something else is apparently goofed up somewhere. I'm going to buy one of those voltage testers today and see if I have any luck with that. I doubt it, but it's worth a try.
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use a 25 watt light bulb never a digital VOM it will give you unusable readings by capitance coupling
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use a 25 watt light bulb never a digital VOM it will give you unusable readings by capitance coupling.
---------------------------------------
The type of device I am going to buy is like the one in this link, I think:
http://homerenovations.about.com/od/electrical/p/voltagetester.htm .
I'm guessing it's not really a volt meter. Instead, I think it is a device that you touch to one wire (not two) to see if it is "hot". I'm not sure that type of device could work by touching a wire that no current is flowing through, but I saw a heater guy using one (he was in love with it) and he claimed that even with no current flowing, it can tell of the wire is a hot wire or a ground. Beats me, but for around 15 bucks I'll have a new toy, so I'm going to try it.
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BETA-32 wrote:

You are correct, it detects voltage and will detect a "hot" wire. You don't need current flow in the wire - there will be voltage with or without current. ("Indicates live current" in the description is technical illiteracy.) Real handy for K&T. It is non-contact - you just touch the outside of the wire insulation. Neon test lights can also be used but require contact.
--
bud--

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Thanks. That "Indicates live current" wording did have me wondering. I didn't get to go and buy one yesterday but I will today.
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Well, I bought the toy and it works great. But, in my case, none of the wires that go to either 3-way switch are "hot". Same for the wires to the actual hallway light. So, there must be a broken wire or bad connection somewhere else in the circuit.

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That sounds right. If you can see the wiring from the attic or basement would be the next place to go for clues.
Trying to re feed the switch from another circuit sounds like the only way to continue.
Do each 3-ways have only 3 wires? Does it look like wiring has been removed from any of the boxes?
wrote:

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I will be heading for the attic in a day or two, especially now that I have the tester.
Both 3-ways have only 3 wires and it doesn't look like any wiring was removed from either one. It all looks like the dusty old original wiring, and the switches I took out and replaced look like they were the original switches -- ancient.

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Attic and basement are real good ideas. Your new toy should be a big help.
If you get stuck, another method of attack is check continuity between possible ends of wires to see what the actual wiring is. Include the light sockets. (I would also verify the socket screwshell connects to the neutral.) When measuring continuity you have to watch there is not voltage between the wires. If you don't have a good understanding of 3-way and 4-way switches (one of the switches was 4-way?) this method may not help. If you work out what the wiring is you can determine which wire should be the hot feed and trace it. K&T wiring problems can be a PITA.
--
bud--


BETA-33 wrote:
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Thanks. A long time ago, I did use a continuity checker and tagged each of the 3 wires for each 3-way switch and the two wires for the light fixture. I have them numbered so that #1 on one end is directly connected to #1 on the other end, etc. Of course, after I did that, I had no idea what to do with the information.
And, no, there are no 4-way switches -- just two 3-way switches.

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There are 2 ways a 3-way might be connected with K&T. In both, 2 wires go between the 3-way switches. And at one end the 3rd wire goes to the light socket connection to the end of the light bulbs.
=================In one way of wiring, the 3rd wire at the other switch goes to the other (screwshell) terminal at the light sockets. This is not a good way to wire a light.
=================The other (more likely and preferred) way of wiring a 3-way, the other wire at the 2nd switch does not connect to the light socket. **This will be the hot feed to trace.
(With both wiring methods the 2 wires between the switches connect to the same-colored terminals on the 3-way switches.)
=====================Don't know if you noticed - Terry started a 2nd thread on this 2-1.
--
bud--


BETA-33 wrote:
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Thanks. I'll have to check this out a little more on Tuesday. Between now and then I won't be home while it's daylight outside when I can see everything with and without the power on.
I went into the attic this morning, and part of the floor is already up from when I was working on it before. But I have to take another board up to access above the light, and I didn't have time to do that today.
I didn't see the other thread that Terry started on this, but I'll go there now.

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On Wed, 30 Jan 2008 11:25:52 -0800 (PST), " snipped-for-privacy@aol.com"

He is going to get an inductance pocket tester which is about all that will work with knob and tube. (and a "for sure" bonded water pipe)
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On Wed, 30 Jan 2008 13:58:11 -0500, "BETA-32"

So you have a light fixture that hasn't worked since you moved into the house?
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