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I live in a 1977 vintage apartment building in the US. I have two 3-pole switches for my bedroom entry light, which are not working correctly. The one switch must be left in the "up" position all the time in order for the other switch to be able to turn the light on or off. They do not work independently of each other like they should. Upon opening up both double gang switches, I noticed that one of the white neutral wires on each switch is separated from the others. Could that be the missing traveler wire? Also, does a three pole connection require use of a 14-3 cable, which has a red wire which I hear is the only color for a traveler wire. One double gang box has four 14-2 cables. The other has three 14-2 cables and one 14-3 cable, but that is already being used for a switch controlled outlet.

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    Can you post photos of the insides of the switch boxes involved? – ThreePhaseEel Jun 29 '17 at 0:22
  • In 1977 it wasn't uncommon for a white to get used as a traveller -- in that case it's not neutral tho, it's a white traveller. If it were new wiring today, it's unlikely to find a white wire used that way, because of changes to code that now require neutrals to be carried to switch boxes. – Tyson Jun 29 '17 at 1:20
  • @ThreePhaseEel I cannot add photos. So far, nobody has said clearly whether a 14-3 cable is necessary for 3-pole connection in the US. – MJCallinall Jun 30 '17 at 20:39
  • @MJCallinall -- post the photos to imgur then and link them here if you cannot upload them -- or is the barrier that you can't take them? – ThreePhaseEel Jun 30 '17 at 22:05
  • Three-phase eel… using Imgur may work. But long story short, if I need to have it re-wired with an additional 14-3 wire between those two double gang boxes, then there is no point in going through the trouble with photos (believe me, it would be a lot of trouble). So far, nobody has clearly said whether or not I need to have an additional 14-3 cable wired in. If that is the case, then I will just screw the switches back in and hire somebody to rewire it, and meanwhile just continue to have it the way it was. – MJCallinall Jul 1 '17 at 18:09
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The answer is yes in 1977 the white was regularly used as a switched leg. There are 2 travelers. It sounds like someone has replaced the switch in the past and mixed up a common for a traveler ( in This case common is the switch contact that toggles from 1 traveler terminal to the other) This is quite common in DIY where someone did not pay attention to the original wiring.

  • APOLOGIES TO ALL! Actually, both switches only had 2 (not 3) wires connected to them. And they were SINGLE pole switches. But I know that they should be 3-pole switches. Somebody took out the original three pole switches. Sorry for my failing to state that in my original post. One wire is the black "hot" that goes to the "common" screw. Also, that the other wire that was connected to each switch was one of the traveler wires (which were BLACK, not white). That's why I asked about white travelers. Could somebody have removed the 3-pole switches because that 3-pole connection had a problem? – MJCallinall Jul 3 '17 at 22:58
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The governing rules here:

  • green, green/yellow or bare must be ground.
  • white or gray must be neutral.
  • any other color is a hot wire.
  • a white or gray wire can be re-marked to be a hot wire with tape, shrinkwrap or paint. Historically the marking could be omitted if the usage was "obvious". In practice this meant the electrician was in a hurry. Generally you re-mark with a color legal for a hot.

In a 3-way (UK 2-way) switch loop, all the wires are hot. So yes, you would re-mark a white wire as another color.

Give n free choice of wire color, it's fine to make both messengers the same color. They should be distinct from everything else, though.

Today, there is an NEC requirement to bring a real neutral wire to most switch locations most of the time. In that case, a switch loop would use 14-4 cable, or 14-2-2, which is now becoming more readily available for that reason.

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14 ga wire is okay for lights only. 12 ga is for general use around the house. 10 or even larger is for special heavy loads. There are, of course, calculations around this stuff, that you should look up in such cases. The main point, however, is that 14/3 is okay for the scenario posted. (There exists 12/3, of course, which also would be okay, but not necessary.)

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