Comments by "Jovet" (@jovetj) on "3 Way Switches Explained - How to wire 3 way light switch" video.

  1. A regular switch, sometimes called "two-way" has two terminals. When it's ON the terminals are connected; when it's OFF the terminals are not connected. A "three-way" switch has three terminals, and must be used in pairs to provide two switching locations. A "four-way" switch has four terminals, and can be used with two "three-way" switches to provide three or more switching locations.
    3
  2. Remember that some of the wire colors will vary. He showed some of the white wires (with black tape) being used to connect to the common terminal, but others might use them as a traveler.
    3
  3. Electrical boxes are required by the Electrical Code.
    2
  4. *common All the wires on a switch are "hot" (except the ground wire, if any).
    2
  5. “Because the neutral coming from the light and going into the second switch box is now re-identified as a hot” Let's be precise with our terminology here. If it's a Hot, then it is NOT a Neutral. The white wire running between the light box and the second switch is not a neutral, even though it is white. That's the reason for the black markings—it's a Hot wire. The neutral in the circuit shown goes from the service panel, in and out of the first switch box, and then into the light box to the light fixture. Yes, it is a Code violation (for both Options 2 and 3 shown in this video) for locales enforcing the "neutral in every switch box" requirement. The simplest solution is to run a second cable out of the second switch and back to the light, and in that case you don't need the travelers going through the light box at all, and it becomes just like Option 1 shown.
    2
  6. To have more than one device (e.g. light) be switched, you'll have to run additional cables to the additional devices.
    2
  7. Three-way switches are very common. As doug m wrote, they're used when you want to control a device (such as a light) from two or more different locations. For more than two locations, you start adding four-way switches in between the two three-way switches. ANY of the switches can change the state of the light.
    2
  8. A "traveler wire" only exists between two three-way switches. The wire after all of the switches to the light(s) is not a traveler.
    2
  9. As he said, you wired them in series. Once you're out of the last 3-way switch, that switched hot needs to go to your light or outlet. If you have more than one light (or outlet), then you need to run additional cables to each light and connect them all together (all the hots together, and all the neutrals together).
    2
  10. If by "crossed" you mean reversed... then the switches will still operate just fine. It doesn't really matter. The way it's shown, the light will only be ON if the handles are the same (up-up or down-down). If the travelers are reversed somewhere, then that may not be the case, but it won't really affect the operation any because all of the switches will still work. If by "crossed" you mean accidentally connected together... then all the switches in the circuit before that crossing become useless and won't do anything.
    2
  11. And 4-way switches are cross-wired DPDT switches!
    2
  12.  @nikkimalones1324  The names used in the USA and in Europe and the rest of the world, are different. From a European context, yes, a one-way switch is the same as a regular switch in the US. In formal terms, a regular switch is SPST (Single-Pole, Single-Throw) while a "3-way" switch is SPDT (Single Pole, Double-Throw) and a "4-way" switch is a cross-wired DPDT (Double-pole, Double-throw) switch.
    2
  13.  @nikkimalones1324  You are welcome, I am glad I could help.
    2
  14. You mean at about 2:55? Because it's not a single wire. The first cable comes in from the service panel, and goes to the first switch box and stops. Then a second (3-wire) cable goes from that box to the second switch box, and stops. Then a third cable goes from that switch box to the light. Even if you were not completely changing types of cable, it would be too time consuming to try and split open a cable so you don't cut the white wire. This all assumes you're using nonmetallic sheathed cable, which is the most common in homes. If you were running this circuit a conduit, you then would have precise control over each conductor, and could definitely make just one continuous long white wire. Just make sure you leave a loop or two in each box it passes through, just in case it needs to be tapped into later. Those are wire nuts not "caps."
    2
  15. Not quite. The travelers can be wired in any way, and then your XOR won't work. The simplicity is the selection of the alternate path to complete the circuit no matter switch switch is used.
    2
  16. That's a pretty recent code change, but yes.
    2
  17. In most residential situations, you are using non-metallic-sheathed "Romex" cable. You don't have a choice of wire colors. NM-2 cable is Black and White; NM-3 is Black, White, Red, BNM-4 is Black, White, Red, Blue (or Black, White w/black stripe, Red, White w/red stripe). You have to use the wire colors you have as efficiently (e.g. cheaply) as possible. When the white wire is NOT acting as a neutral, it's supposed to have the black markings on it at each end. In that situation, it's another hot wire, not a neutral.
    2
  18.  @Dedread  It is very simple. Where the white and black wires go to the light fixture in the video, simply splice additional wires to go to all the other lights.
    1
  19. Staircases are a better example. No point in having a light for a staircase that is only operable from just one end of the staircase! It's not just a convenience issue, it's a safety issue. Consider a kitchen, or living or dining room, that has 3 entrances. A switch should be placed at each entrance which can operate the room's light. It's not just a safety issue, it's a convenience.
    1
  20. What? The guy wire holds the pole up so it doesn't get pulled over. It doesn't carry current or have any grounding function.
    1
  21.  @tedlahm5740  Oh, I think I see what you're talking about. A "wire" that holds up other wires in an arial catenary but carries no current itself is called a messenger wire. The reason the neutral does not need insulated is that it's grounded at that point. It's grounded at distribution transformer, and it's grounded at the service panel it's going to.
    1
  22. Why do you say that? Option 1 is the most straightforward.
    1
  23. The load controlled by the switch determines what size circuit breaker is required, as well as the size of the wire.
    1
  24. If you want the outlet to be on all the time, then you can only "tap in" where the power from the panel comes to the first switch, and there must be a neutral in that box. If you want the outlet to be switched by the three-way switches, then you can only "tap in" after the final switch, and there must be a neutral in that box.
    1
  25. The idea is to use a single 3-conductor cable, to keep costs down and simplicity up. A three-way switch inherently requires three hot wires, so using 3-conductor cable works out. Marking the white wire as hot is an "exception" that lets this cost-effective practice work. Newer codes forbid this practice in most instances. You either need to run an additional cable to handle the switched load, or install less common 4-conductor cable to ensure a neutral wire is present.
    1
  26. Examine the wires and the terminals on the switches. Many devices will let you do this just by taking the cover plate off the switches. Usually the "Common" terminal is darker than the others. If you can see that, you should be able to see what colors the wires are going to each terminal. If you see some whites connected, then you have Option 2 or 3 listed here. In that case, you'll need to shut the power off, and remove the unscrew the switches from the boxes, and inspect the cables going in and out of the boxes to figure out which is which.
    1
  27. Options 2 and 3 no longer meet code for locations where the Code requires neutrals in every switch box (with a few exceptions). The options shown in the video are perfectly safe, have been used for decades, and are more economical, but the Code changes are for future-proofing with smart devices which require power to operate. As a general rule, every switch box must have a neutral conductor in it, even if it's not initially used. This means Options 2 and 3 would either have to have a separate cable ran beyond the second three-way switch and back to the light, or a 4-conductor cable installed.
    1
  28. Aren't those illegal?
    1
  29. It's kind-of like the second scenario in the video. Power comes in to the light, and the hot goes from there (on the black) to one of the switches and connects to the Common terminal. The white (marked black) and red wires carry the travelers from that switch back to the light box. There, they join the same-colored wires going to the other switch. At the other switch, the black wire connects to the Common terminal, and comes back to the light box, which is connected to the light. The neutral from the source in the light box is connected to the light figure and that's it.
    1
  30.  @nikkimalones1324  I am not sure what you mean by S1 or S2. Please clarify.
    1
  31. In the United States, the following colors are standard: – White, Grey = neutral – Green, Green w/yellow stripe, bare = ground – Everything else can be considered some kind of "hot" or "live" conductor. A white wire marked black at each end is also a "hot" wire. The red extra "hot" wire can be used for several different things. In these switch circuits, it's used as a traveler to join the two three-way switches together.
    1
  32. I'm questioning your answer.
    1
  33. Depends on what you mean by "servicing a light fixture" and "hot lead at a light bulb." If you mean one of the contacts on the light socket being perpetually energized, then I agree. But none of those are shown in this video. There are no "permanent hot leads" at a light bulb in this video. If you mean merely having an always-hot line in the fixture box and then opening up the fixture or electrical box to "service" it, then I disagree. You're supposed to shut off the power before messing with any wiring anyways. If you are referring to crazy old wiring schemes like "Hot 3-ways" then yes, I agree. Those are more dangerous and are illegal for a reason.
    1
  34. Because cables are installed from box to box, and it's faster to splice them than to try and keep them continuous.
    1
  35. It's called a Three-Way Switch because it has three terminals. It doens't make much sense, but that is what it is. For more than two switches controlling a light, you simply add Four-Way switches between the Three-Way switches. There can be any number of them. (Guess how many terminals a Four-Way switch has?)
    1
  36. There would need to be an additional "hot" wire between the two lights to power the left light from the right light.
    1
  37. Remember that the wires shown are encased in cables going from electrical box to electrical box. It's much simpler and faster to cut and splice them than it is to try and make certain wires continuous through an electrical box.
    1
  38. It doesn't matter. As long as the light changes state when any switch is flipped, it's fine.
    1
  39. What would be the scenario for no neutral?
    1
  40. Wiring outlets together is very simple, for most circuits. Each duplex receptacle has four screws (plus a ground), so the cable coming in can have its wires to one set of screws, and the cable going out to the next receptacle can have its wires connected to the other set of screws. Connect the grounds by making a pigtail as 4-6 inches of bare copper wire, and connecting one end of the receptacle, and combine the other ends with the incoming and outgoing bare grounds with a wire nut or equivalent. If your circuit involves a GFCI, then make sure it is the first outlet in the circuit. Wire the incoming cable wires to the LINE terminals, and the outgoing cable wires to the LOAD terminals.
    1
  41.  @nuarius  Sure thing. I'd also like to add that using a white wire as a "hot" in a switch loop is one of the rare wire color exceptions allowed in the US Electrical Code. And, a few years ago, the code was revised to force more expensive cable be used so a neutral conductor can be ran to a switch box that wouldn't need one. The idea is future-proofing against the need for a neutral later, were a smart device to be installed to replace the switch.
    1
  42.  @nujomaclarke8064  Just sits in there, with a wirenut on it. It's there for future-proofing, in case a smart device that needs it is installed later.
    1
  43. Yes. But that's extra money because that cable is more expensive and harder to find.
    1
  44. Yes it can be done, but it may not be the most convenient.
    1