Connect 3 way switch with no neutral

  • I'm new to this forum and have just received my first shelly 1pm now when I want to start hooking it up to my ventilation system of my house. The system itself has a switch similar to a shutter however I noticed I only have 3 wires in my 3 way switch. 1 brown wire 1 full black and 1 black and white. When switch is in neutral the ventilator is off, when on 1 it is on speed 1 and 2 on speed 2. All of the wires seem to have power on it when checked with a screwdriver with electric indicator.

    I was wondering if I could insert the shelly 1pm to one of the wires. Should I need power for the shelly to run I could steal that from the electric socket next to my switch.


    Any idea how I could hook up the wires properly so I could use it as on/off for one of the speeds?


    15690941578766035779071596447923.jpg

  • Hello,

    yes you can use a Shelly 1PM for switching of one of the two speeds of your ventilation system. And yes you need a power supply for the Shelly L and N. You only need to check carefully with an multimeter if the socket and the switch are connected to the same phase/breaker. But don't forget 230V are very dangerous and if you are not familar with this please call an electrician to do this work for you.


    Nevertheless I would recommend you to use a Shelly 2.5. Then you could operate both fan speeds AND maybe could use the Shelly in roller mode with interlocking between the two speeds.

    Grüße Bernd


    Mein "Smarthome":

    FHEM als "Master"(Cloud-Free :))mit 85 Shellys(1, 1PM, 2, 2.5, 4Pro, RGBW2, PlugS, alle mit Original-FW),13x Sonoff (Tasmota-FW),12x Blitzwolf/Gosund(Tasmota-FW), 85x One-Wire Temp-Sensoren(16x D1-Mini mit Tasmota-FW),51x Modbus(Hutschienenzähler),31x Intertechno 433MHz(Rolladen-Aktoren),12x FBDECT(8 Heizkörperthermostate, 4 Schaltsteckdosen),21x Homematic(16 Raumthermostate, 3 FB-Heizungsaktoren, 2 Repeater),etc. ...

    Neues von Print Worth 3D: ==> Marktplatz

  • Hi Flinka , welcome in our forum. :)


    First:

    ...All of the wires seem to have power on it when checked with a screwdriver with electric indicator.

    ...

    This is the worst tool choice for this task.


    In professional circles they like to call them "Lies-Stick" and in my business the use is strictly forbidden. (In the case of a defect, they can cause an electric shock and you can die.


    Please buy a suitable measuring device. That's for your security.


    With a multimeter or a 2-pin voltage tester, you can certainly determine what is on the individual lines of potential.


    Thank you.:thumbup:

    ...

    Any idea how I could hook up the wires properly so I could use it as on/off for one of the speeds?

    ...

    For a qualified and effective answer you have to measure the electrical current (A) in both modes.


    Because if a Shelly 2.5 can switch the power, it would be the better choice.


    If you can not do the measurements safety yourself, please contact an electrician of your trust!


    Edit:

    Bernd was writing faster.

  • 15691596467132130145843136095896.jpgthanks for both of your answers. I have reassured with a multi meter and basically

    2 wires have 240v and one wire goes back to ventilator. It seem there is no neutral and I cannot use the neutral from the other socket since this is on a different breaker. Any other ideas how I would be a able to hook up the shelly?

    I guess since there is no neutral a shelly 2.5 wouldn't work here also?

  • Can you do without the switch and insert a blind cover?


    Then you could install 2x Shelly1. The voltage you take from the socket and with the potential-free contact you switch.;)

  • So I would put voltage on line input(L) and free contact on output (O)? However then the shelly doesn't start because it doesn't have a connection on N(eutral) input right?

  • No.


    You take the voltage for the shelly (L) and (N) from your socket.


    (o) and (I) is a potential-free contact, wich you take for the wires to the ventilation.


    If you are not shure, please ask an electrician.

  • ah as my initial plan already. In the 1pm the schema is not the same as in the 1 which is causing my confusion for that setup. I would have my neutral and l1 connected to the wires of my other socket and then 0 for one of the wires of the ventilator, however l from the shelly 1 would be the L in shelly 1pm?

    15691651943695379400390310838028.jpg

  • Hi,

    I'm not sure if you understand correct what Stefan explained.


    If you have two different breakers for the socket and the fan switch you cannot use a Shelly 1PM. The only possibility is to use one (for one speed only) or two Shelly 1 (to be able to switch both speeds on) because only Shelly 1 has clean relais contacts.


    1. You need to supply the Shelly 1 from your socket (L+N).
    2. Even the power supply for your switch has to come from the socket breaker.
    3. The output of the switch for speed 1 you have to connect to the SW of the first Shelly 1.
    4. The output of the switch for speed 2 you have to connect to the SW of the second Shelly 1.
    5. Then you connect the power supply for the switch (from fan breaker) to the Input (I) of both Shelly 1.
    6. The wire for speed 1 (to the fan) has to be connected to the Output (O) of the first Shelly 1
    7. The wire for speed 2 (to the fan) has to be connected to the Output (O) of the second Shelly 1.

    But you need to be aware that in this case you have no interlocking of the two speeds of your fan by using the APP or browser interface.

    Grüße Bernd


    Mein "Smarthome":

    FHEM als "Master"(Cloud-Free :))mit 85 Shellys(1, 1PM, 2, 2.5, 4Pro, RGBW2, PlugS, alle mit Original-FW),13x Sonoff (Tasmota-FW),12x Blitzwolf/Gosund(Tasmota-FW), 85x One-Wire Temp-Sensoren(16x D1-Mini mit Tasmota-FW),51x Modbus(Hutschienenzähler),31x Intertechno 433MHz(Rolladen-Aktoren),12x FBDECT(8 Heizkörperthermostate, 4 Schaltsteckdosen),21x Homematic(16 Raumthermostate, 3 FB-Heizungsaktoren, 2 Repeater),etc. ...

    Neues von Print Worth 3D: ==> Marktplatz

  • Ah ok now is clear, thanks for taking time to explain.

    I will order a shelly 2.5 to tackle this, makes more sense in the end than to toggle with 2 shelly 1's

  • That was my suggestion from the beginning,

    but again:

    In this case you need to connect everything to the breaker of your socket because the Shelly 2.5 does not have clean relais contacts!


    Another solution could be to use only th N from your socket circuit, but only if the N from the socket is the same as for the fan circuit. Anyhow this would be a case for a professional electrician to check out the correct connections because I don't know how the rules for installation in your country are and if this is possible. Maybe you have two-pole breakers which disconnects L und N together Then it's not possible/not allowed to mix N from two circuits.

    Grüße Bernd


    Mein "Smarthome":

    FHEM als "Master"(Cloud-Free :))mit 85 Shellys(1, 1PM, 2, 2.5, 4Pro, RGBW2, PlugS, alle mit Original-FW),13x Sonoff (Tasmota-FW),12x Blitzwolf/Gosund(Tasmota-FW), 85x One-Wire Temp-Sensoren(16x D1-Mini mit Tasmota-FW),51x Modbus(Hutschienenzähler),31x Intertechno 433MHz(Rolladen-Aktoren),12x FBDECT(8 Heizkörperthermostate, 4 Schaltsteckdosen),21x Homematic(16 Raumthermostate, 3 FB-Heizungsaktoren, 2 Repeater),etc. ...

    Neues von Print Worth 3D: ==> Marktplatz

  • Thanks for your additions, Bernd. :thumbup:


    I think, using an electrician is the best advice we can give here when I look at the overall discussion.

  • The diagram that comes with the product doesn't make sense to me.


    Think of L and N like the power supply for the relay - normally always has power unless you are doing something very uh.. creative.


    L1 and O circuit will be close when the SW is activated or toggled.


    You could use the same wire for L and L1, although in reality it could be a different power running through L1 and O than the one powering the relay (L and N).


    What you might not want to do, is have L1 and L come from different circuits if possible, because then that neutral might not be enough to carry the current from both circuits, and since there is no relay on the neutral wire, you might have bad things happen.