Forums » Electrical Engineering

3way switches

    • 38 posts
    May 17, 2019 3:58 AM PDT
    Hello Gents,

    There are two three way dimmer switches but I need to use one switch for a light on and off. Is there any way to control additional light separately ?
    • 148 posts
    May 17, 2019 8:53 AM PDT

    I think you need to be more specific.  I cannot understand what you are trying to do

    • 200 posts
    May 25, 2019 8:36 PM PDT

    Thanks for the suggestion of this topic, Rajish. Sorry for the late reply.

    Let's consider the simple 3-way switch diagram (i/o meaning input/output of phase, on to point 1 in the example):

        +---+
        | 1o--
    i/o---/ | 3wS
        | 2o--
        +---+

    Now, let's connect TWO simple 3-way switches to a lamp in next diagram (one switch as "in" other switch as "out"):


        +---+              +---+
        | 1o----------------o1 | 3wS#2
    in ---/ | 3wS#1        | \---out------(X)---> to Neutral or 2nd phase
        | 2o----------------o2 |        Lamp ON
        +---+              +---+      both 3wS to
                                      same point 1

    Let's assume the dimmer 3-way switch diagram is as below, correct if I am wrong please, [DIM] is the dimmer in input only, bi-directional circuit not considered so output as not represented here:

              +---+
              | 1o--
    in -[DIM]---/ | 3wSdim
              | 2o--
              +---+

    If you want to use just one dimmer 3-way switch for just one lamp (incandescent/filament type for dimming), don't need to use both points (1 and 2), use just one point (point 1 in this example) and leave other point free/empty (point 2 here) like in the diagram below:

              +---+
              | 1o--out--------------------(X)---> to Neutral or 2nd phase
    in -[DIM]---/ | 3wSdim               Lamp ON
              | 2o--                    3wSdim to
              +---+                      point 1

    I think it will work. Regards.


    This post was edited by Alex de Moura at May 25, 2019 8:42 PM PDT