Help about home automation (Relays)

I want to do home automation in my house with Arduino to control the light, t.v, air conditioner and more.
I know that when you need to connect low-voltage with high voltage you will need a relay but I don't know what kind of relay I need to the light in my room for example or to my t.v, I upload a picture of the relay that I have in here and my voltage that comes to my house is 220V.
I hope that someone could explain to me how do I know what relay do I need to use for every component that I want to use it with Arduino and if I need to measure something so how do I do it?

Hi @MainGod159
one of the solutions to control lights, TVs, air conditioning, etc.. really is the relay.
Simply put, the relay has specs.
The voltage, and the voltage and current that it supports to control.
The photo you posted is a module that contains a relay.
In your photo, the blue block is the relay.
It has written this information.

10A 250VAC 10A 125VAC
10A 30VDC 10A 28VDC

The first two lines inform the current for each voltage of the device that it will control, and in this case it is the same current for several voltages.

The third line tells you which voltage the relay operates.

For home automation projects, I don't recommend this relay module model you posted.
The reason is that he is not an isolated opto.

RV mineirin

PS: This model is opto isolated.

The other thing to look at is the PCB design, make sure there is sufficient spacing between the low voltage control/coil circuit and the Mains input side of the PCB.
The safest PCB are one that have a piece of PCB cutout between the two areas, under the relay to ensure isolation.

Tom... :smiley: :+1: :coffee: :australia:

TV and lighting I would not expect to be too bad, but the breaker for my A/C is 40A at 120V, so that relay certainly couldn't cope.

That relay board has the typical Songle relay on it. I regard them as fine for hobby projects and short term or prototype work, but I wouldn't want to rely on them for anything important long term - they're just so inexpensive that they don't seem likely to be suitable.


I agree, look for OMRON or even FINDER at major parts suppliers, you could even find one with the same footprint to put on the PCB.

Tom.. :smiley: :+1: :coffee: :australia:
PS, Check out the home automation sites/forums to see what their solutions are.

Right :+1: :+1: :+1:

The page How to Add Relays to Arduino covers a variety of relays for use with Arduino.

Hey, thank you for your answer.
The module that you posted is a relay module that supports all kinds of home automation like: light, t.v, etc..? If yes so can you tell me the full name of the module please? And last thing just to make sure, in the picture that I posted it supports only 250VAC or 125VAC with 10 current and 30VDC or 28VDC with 10 current and this is the voltage and current of the device that I will control?

You could decide to use a Controllino, they are more expensive but they have state of the art relay outputs that do directly 16A @ 220V, you can also fix them on a DIN rail in your main electrical cabinet.

Now, 1 thing (depending on the legislation of your country) can be of importance:
If you use non CE approved components, and certainly make them part of your house automation that is fixed (without a socket between the mains an your component), they you are bound to use CE materials. If the thing catches fire, and you do not use CE materials, fire insurance can be problematic in case of an incident. In fact in Belgium you need to have your modification approved by a notified body. So be carefull and know what you are doing.

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