Currently to turn on/off the bedroom light I have to get out of bed, I want to enable switching off the bedroom light from the bed with a switch either side of the headboard and at the door. Elsewhere I would need 2 3way and a 4way switch as in the diagram :

sparky says "mai dai, mai mee"....looking through Thai watsadu website I found that 3 way switches (common,L1,L2 terminals) are called 2 way here. I assumed that would make 4 way switches 3 way but I cannot find anything listed at Homepro, Dohome or Thai Watsadu. Only one way or two way. Are "4 way" switches not available here ?

Officially, a "4-way" switch is called a "double-pole, double-throw" switch.  You might try looking for something along those lines.  I would think Thai Watsadu should have them, but I don't know.  They do have more variety than some of the others.  I've never actually purchased one in Thailand--but have installed them elsewhere.

 

Yes, you definitely need a 4-way for any switch in the line sandwiched between two 3-way switches.  You can use as many 4-ways as you like, but you will also need to have three wires running between them (two hots plus neutral), instead of just the hot and neutral for a normal circuit--unless you are creative with the neutral line.

 

There are always two ways to wire a light: Power to the switch, or power to the light.  The former is best, as when the switch is off, you won't risk electrocution to work with the wiring at the light.  In the case of two or more switches, the power must enter at one of the 3-way switches, with the light connected at the other one.

 

 

thailand supply store for electrician have switch 4 way type sometime have other name like intermediate or changover type

 

panasonic WEG5004 is example

 

Smart bulbs,  a smart speaker (i.e.: Amazon Alexa) and turn them on and off with a voice command. No wiring needed. 

11 hours ago, MikeN said:

Are "4 way" switches not available here

The problem you are having is in the name and looking in the wrong place. You need to go to an actual electrical supply shop and discover the way a Thai will name them, then you will find them either in stock or available to order.

 

The problem with looking in places like Homepro, Dohome or Thai Watsadu is that they carry the small percentage of items that make up 98% of the stuff people need and don’t bother with the 2% that few people want, and few Thai sparkies understand how to use.

Centre switches are commonly known as "intermediate switches".

https://www.electricalcounter.co.uk/what-is-an-intermediate-switch

You could use smart switches and relays.

With those you could have 10 or more switches for the same light bulb.

Home - Shelly Cloud

 

21 hours ago, OneMoreFarang said:

You could use smart switches and relays.

With those you could have 10 or more switches for the same light bulb.

Home - Shelly Cloud

 

Well yes and also if one went to a system like cbus from clipsal at a rather hefty cost, one could have even more.

Up to 256 addressable switches per relay or even more with some software haggling.

1 hour ago, bluejets said:

Well yes and also if one went to a system like cbus from clipsal at a rather hefty cost, one could have even more.

Up to 256 addressable switches per relay or even more with some software haggling.

The Shelly switches/relays are relative cheap. I guess they also work stand alone. I use them with Home Assistant. That software is free, and all runs local - no big brother is watching. 

On 9/29/2022 at 1:09 AM, OneMoreFarang said:

The Shelly switches/relays are relative cheap. I guess they also work stand alone. I use them with Home Assistant. That software is free, and all runs local - no big brother is watching. 

Do you keep the shelly firmware or go with ESPhome or Tasmota?

3 hours ago, tjo o tjim said:

Do you keep the shelly firmware or go with ESPhome or Tasmota?

ESPHome and Home Assistant, and NSPanel and a lot more... 

Something about the "cheap" would be of concern I'd imagine.

Plenty of insurance....???

mmm...maybe of no help considering the use of possible non-compliant equipment.

As they say, the bitter taste of poor quality remains long after the sweetness of cheap price is forgotten.

10 hours ago, bluejets said:

As they say, the bitter taste of poor quality remains long after the sweetness of cheap price is forgotten.

Very applicable, and it's a saying I'd always loved in the past, but had forgotten about, and I remember thinking it was very similar to a quote from the English philosopher, John Ruskin.

 

So very true though.