Yes, that is correct. in fact wires in conduit have to be de-rated more than the wire embedded right in cement plastering.

By switch you meant 3-pin sockets? Light neutral and switches neutral confused me

This depends on house wiring. It can trip and it also cannot trip the CB

Sonoff Pow is a wireless smart power switch with electricity usage monitor feature. The Sonoff Pow remote power switch works like an electricity consumption calculator( kwh calculator), it allows users to calculate electricity usage and remote control the connected electrical devices by the App EWeLink.

https://www.itead.cc/sonoff-pow.html

Is the TH-16 UL certified? I think not. The certs provided are on RoHS, RF and others, but not about real prolonged operating load.

The spring loaded connector will create heat and melt connector over long period. I've read many reports on failure even for short shower usage period repetitive usage on water heater. I would still recommend the use of contactor for safety reason.

https://support.itead.cc/support/discussion...ics/11000012976

That is why some say it is more like DIY/hobbyist device than real fixed installation stuff. The trace was a problem but the way sonoff deal with it is by adding thick solder on the copper trace

I'd say you need to place the device at location you can see or easily reachable instead of on ceiling to as precaution.

I think you or someone else mentioned about this recall before. I was surprised that the problems mentioned in the link I provided are very recent (even days ago) reported even though the topic was opened 2 years ago. I wonder the seller ignore recall and sell old stock

Since there is no need for it. As you can see the wiring is like diagram provided by Archdruid. Where do you want to connect the N wire to the switch. Normally the switch is SPST and not DPDT like the 20A switch.

The fan normally share the same loop as the lighting and connected to 6A MCB.

Convenience is nicer term instead of laziness

I consider if you have extra money and automation is your hobby that can make you happy, then why not. I weigh my judgement more in practicality I guess.

Light and ceiling fan can share same L loop on 6A MCB (6 lighting + fan points max if not mistaken), but water heater usually use independent line which normally controlled by 1 20A MCB using DPDT switch.

The 1HP aircon usually is just plugged to 13A socket. If 2x13A sockets share same wiring, it goes to 20A MCB. If 4x13A sockets on same wiring, it goes to 32A MCB.

Just put the unit at ceiling location and keep the switch on the wall on.

My bad. I was thinking of other sonoff

I don't have sonoff to try modification that will enable sonoff wall switch to operate without N wire

Use the smart switch to trigger the contactor inside that big box perhaps (simulate the button pressing)?

I have not done anything like this either

The button you press is like momentary switch. Once pressed, the switch power electromagnetic switch that trigger another high power switch which is then held in ON position by mean of electromagnetic even after you release your finger from the button.

So, the idea is to get the smart switch to replace your finger. What you need to do is to connect the smart switch parallel to the push button. However, since it is only need to be momentary action, you need to on and then off the smart switch (not really smooth idea )

Someone correct me if you think this will not work.

Yes. This is called starter. The main purpose of starter is to protect the motor from damage. For small motor like the one used in home air-cond, the protection is build inside electronically inside the motor controller.

When power on, the current inrush into motor can be very high thus can damage the motor. The starter usually has coil inside to reduce inrush current and after motor start operating the resistance coil is by-passed for full load operation. Usually high power air-cond require starter.

When press the button, only low current flow to trigger electromagnetic contactor switch inside the starter. That is why I said the push button operation can be replaced with smart switch with momentary action.

Well, it is not like normal plus minus simple arithmetic. If you add all 3-pin plug (13A) on same wiring, it will not tally to the MCB in DB. For example, TNB stated that MCB C20 is connected to 2x13A sockets. The two sockets total up to 26A, not 20A.

The most important thing is the wire size in the wall, conduit or trunking. The lighting wire is smaller wire (1.5mm²) and heater or air-con bigger wire (4mm²). There are other sizes too and how wiring is done. The MCB is chosen to protect the wire from overload.

Therefore, I'd say it does not matter how many socket or light/fan you want to connect to same MCB. If the total current that flows through the wire exceed the MCB rating, it will trip. Most importantly is that you do not change the MCB to higher rating just because you want to add more sockets or lighting points.

FYI, I'm no charge man or electrician that do house wiring but I do have degree in Elecrrical Engineering. Well, degree and practical experience is different thing as you know. However, I did do own wiring for my house with help from my friend on my house extension and renovation.

Well nothing much you can do about it. As your aircond and socket share same line, the socket might not be using full load at 13A and the 1hp aircond is not running full power all the time. If your MCB trib due to overload, then you need to start thinking of re-wiring. Do not change the MCB to higher rating Just leave it like it is.

I have many spur socket tapped from existing loop used for laptop, TV, printer, etc. It will not cause the problem. A single phase line to a house is only 63A and all your MCB total up more than that I guess

Saw this website

https://smartcurtain.com.my/smart-curtain/

Well, still communication goes both ways. If router can hear your sonoff, it does not matter if sonoff gets the signal

What I meant was the router can have good transmit signal but if it cannot listen to your sonoff then still no communication. It can be that the router has good transmitter but poor receiver. Sonoff signal might not be strong enough to be received by router even if sonoff can receive the signal from router. So, if you check signal strength at sonoff location and the signal is good, it still does not mean that it can work.

The only way is to do real test. It is hard to answer Nando's question because house design and material is not the same. He has to do trial and error. However, your suggestion is the first thing you want to do I was just saying that it could still fail but in most cases, normally it works based on my experience.