I was thinking about how a 4-way is wired. You wire it in pairs so, even though 4-way has 4 wires and 4 screws, you still have a 50-50 chance to wire it correctly.
With a 3-way, on the other hand, you only have a 1 in 3 chance of getting them right.
Also, if you screw up the 4-way nothing will work. If you get it right, then one of the 3 ways will work.
So the OP must have had the 4-way correct.
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.
One position of a 4way feeds straight through II , The second position feeds through in an X pattern. If you wired it wrong, you'd still make a circuit in the X pattern, so depending upon your 3 way positions you could still get a light
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
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.
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.
That's understandable. The boxes are not grounded in a knob and tube wiring system and the other wires are not neutral conductors. Run a long wire from a metal water pipe or from the neutral bar in your fuse box and use that as the second conductor for your tester. You should be able to find the hot that way.
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
So you have a light fixture that hasn't worked since you moved into the house?
Yes. It's a hallway light, and that's the only thing that doesn't work. All other lights, outlets, etc. work. I just assumed it would be something routine like a bad 3-way switch. The switches were both old, so I bought two and replaced both. I took off the light fixture and have just a bulb and a socket wired to the two wires that went to the fixture.
use a 25 watt light bulb never a digital VOM it will give you unusable readings by capitance coupling.
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The type of device I am going to buy is like the one in this link, I think:
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.
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)
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.
Thanks. That "Indicates live current" wording did have me wondering. I didn't get to go and buy one yesterday but I will today.
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.
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?
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.
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.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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