Connect 3 way switch with no neutral

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.

Hi Flinka , welcome in our forum.

First:

Quote from Flinka

...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.

Quote from Flinka

...

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.

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.

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.

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.

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.

Thanks for your additions, Bernd.

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.