The Sonoff 4CH Pro

The 4-channel Sonoff 4CH Pro is a new product from ITEAD, available from them directly or from Amazon in the UK– though you might reasonably question why the UK Amazon price is higher in pounds than the original is in dollars.

Essentially the unit is a development of their earlier Sonoff 4CH and I’ll do some basic comparison here.

Sonoff 4CH Pro[7]

Comparing this with the original 4CH product, you may recall I wrote to them to point out that their connector colour scheme was all wrong – with green as neutral – well, they’ve gotten rid of the colour scheme in total and made several other changes. The handy PCB fuse has gone in favour or a soldered-in-place fuse (I would have thought that was a backward move), the connector layout is more logical, it is now possible to use mains power OR 5-24v DC and the relays themselves look considerably more beefy – a good thing as there’s no way I would put anywhere NEAR 10 amps on those originals.  Tracks look substantial and there are now nice air gaps everywhere for safety.

4CH Pro (left) 4CH (right)

Where the original units claimed CE and ROHS, I note they now claim CE and FC. The toggle buttons are also now easily accessed from the front without having to remove a cover. As well as WIFI access they’ve added 433Mhz remote control – though the actual remote control does not come with the unit.

4CH Pro and 4CH

There are considerably more components on the 4CH Pro than its predecessor and it looks solid – both of course are in DIN-RAIL mount cases.  Whereas before you could hook up mains to the unit and loads straight off the connectors, as the new relays are not attached to anything, you have to have some external connectors to make this all work but then – I LIKE that as the outputs are now totally un-committed. So for example I could be using three of the outputs to control power stuff and the 4th to put across a traditional thermostat contact pair – something you could not do when the relay central contacts were attached to mains power. Clearly being unattached you can also use the normally CLOSED contacts which you could not before.

4CH ProAt £22 from Amazon including postage – and given that you have four outputs – equivalent to and in some way more flexible than four separate mains control units, this seems to represent reasonable value for money. The unit is also compatible with Amazon Alexa which is a plus – though of course using non-standard software this feature has been available for some time though I do note that the software I’m referring to has “future” support for the Pro – he already supports the original 4CH so I’m sure it won’t be long before that is taken care of, at which time I’ll re-flash the unit and update this blog – I’ve put my request in. – I really don’t want to use a special APP with this – preferring my normal MQTT control.

More on this as the Tasmoto software appears for this unit. Up to now it looks like a winner. I’ll soon tell you now near you can get to 10 amps as I plan to control a hot water heater to make use of “happy hour” electricity.

While I’m here – original Sonoffs – Banggood are doing them inc postage – incredible price.



52 thoughts on “The Sonoff 4CH Pro

  1. Hello everyone! I’m new to this Sonoff technology. What should I do to be a Sonoff developer? I’ll start from the 4CH Pro R2.

    1. Personally if I were new to Sonoff, I might consider start off with a simple Sonoff WIFI BASIC – these can be had for as little as under 4 Euros (just over 4 dollars). My own preference would be to kit such a device out with my own ESP-GO software or TASMOTA and go from there but that assumes knowledge of how to FLASH these things. You say you are new to the Sonoff technology but give us no idea of your general level of technical competence or otherwise (hardware and software) which makes it difficult to know what else to say.

  2. Hi, I just bought one 4CH Pro rev2 and had a look at the manual(s). It says you need two relais if you want to steer a motor. I would think this makes sense if you have a three phase motor or one that is over 10a. I don’t understand why you should do this for a simple ventilator using 50 – 100 Watt. Can’t find any further info on this.

  3. Maybe a double posting but it didn’t appear and I didn’t see a message it is awaiting moderation.

    Hi, I just bought one 4CH Pro rev2 and had a look at the manual(s). It says you need two switches if you want to steer a motor. I would think this makes sense if you have a three phase motor or one that is over 10a. I don’t understand why you should do this for a simple ventilator using 50 – 100 Watt. Can’t find any further info on this.

  4. Do you think there is anyway to use this device as a smart speaker selector? I have looked everywhere for a device to replace a manual speaker zone selector which can be used in conjuction with Alexa and/or Google Home and the Sonoff obviously does that, and this one supports an outside power supply to activate the device, but could the device act as a switch for something like a speaker vs. Power for a light…seems like this is a market to be tapped into for retrofitting a home with wired speakers vs having to go wireless…

    1. Hi Mike, I’ve actually been thinking about this but haven’t given it too much thought. The easiest way would be to get a remote speaker zone selector. Something like this . Then use either that control or using a Broadlink Rm universal remote to control the unit via Alexa. Then just use routines select the different rooms. Eg. Alexa, use the kitchen speakers. Then action would be selecting the appropriate zone via the broadlink.

  5. hi, thanks for writing this article, it is very helpful.

    I am looking for the push button extensions they have used. any idea where I can find them?

    1. You’ll have to seek answers elsewhere on that one, I have no interest in CE certification. The whole thing has cost small businesses a fortune over time and put them at a massive disadvantage compared to larger organisations. It also bears a striking resemblance to the China Engineering logo.


  6. Thanks for your help, watched the video but no mention of the K5 switch but he did explain the 4 versions of sonoff so I now know I have the sonoff 4ch pro (non R2)

    I’ve also searched iteads site which always instructs the use of K5 which my board has not got

    I’ve opened a tech support ticket on their site so maybe they will tell me why there’s no K5 but if anyone has seen a board like mine without K5 I would be interested to know how they programmed it
    Thanks again for your help

  7. I purchased sonoff 4ch pro and I’m trying to configure it but there is no work mode switch K5 on the pcb to programme inch mode. (Please see photo). Has anyone seen this board and if so can you tell me how to configure inching without K5 or have I been sold a faulty unit?
    Thanks in advance

  8. I used a Sonoff 4Ch Pro, one of my Genie RF remotes, and two SPDT magnetic reed switches to make my Internet controlled garage doors open and close. The magnetic switches are placed above each door to provide BIAS, to insure that the UP button(s) are only UP and DOWN button(s) are only DOWN. I used four channels on the Sonoff for TWO garage doors. I set them for momentary, 1/2 second delay (inch mode). The first two channels are LEFT DOOR UP, LEFT DOOR DOWN. The other two channels are RIGHT DOOR UP, RIGHT DOOR DOWN. I opened one of my RF remotes, soldered two wires to each button that controls each of the two doors. I’ll explain only one door for simplicity, as the other door is wired exactly the same: One wire from the Genie button connects to both the “NO” terminals on channel 1 and 2 of the Sonoff. The “C” on channel 1 goes to the NC side of a magnetic reed switch. The “C” on channel 2 goes to the NO side of that same magnetic switch. The other connection for that button on the Genie switch goes to the common “C” on the magnetic switch. If a door is down and you press DOWN on the app, nothing happens. If you press UP on the app and the door is up, nothing happens. If the door is up and you press DOWN on the app, and the door goes DOWN.. AND vise-versa. So, if you’re away from home and you think you may have forgotten to close one of the doors, just press the down button for each door and feel safe knowing they didn’t go up (IE open). Works like champ. I have a drawing posted here if anyone would like it. (Note the NO/NC at the switch needs to be reversed on the drawing or the control is backwards).

    1. Thanks for this. Are you using this with Alexa. If so what commands are you using for the different channels ?

      1. Not using with Alexa. If you want to use Sonoffs with Alexa, use Tasmota – support questions to the Tasmota site.

    2. Here’s an updated photo … showing the NC/NO wires correctly. Remember, this drawing only shows one door. If you want to control two doors, repeat the circuit for the other switch and connect to relay 3 & 4.

    1. Thank you or the write up. My plan is to get this to control my 3 garage doors which I believe can be done with inch mode. I plan to flash with Tasmota and from what I read it seems that inch mode can still be set by on board switches but I’m not 100% sure. Also would be nice to get 433 and keep support after changing firmware. Does anyone have different understanding?

      I like the idea of powering with 120v (U.S.) instead of using a wall wart but am I taking a greater risk using AC direct to this small device?

  9. Hi Peter, greetings from Durban South Africa. I bought 3 of these 4 Ch Pro units in the UK recently to use with my Google Home. I like the 4 independent relays, you can put anything through there, though I would like to use them initially to interrupt the power supply to my lighting circuits. My problem is that they all work the same, when you switch on a relay it stays on for a few seconds, and then switches off by itself. I did manage once, by adjusting the settings on K5 and K6, to get the relays operating independently, switching on and staying on, and allowing more than one relay on at a time, but even this controller has reverted back to the factory setting.

    Do you know how to configure them? Your advise will be greatly appreciated

    1. If you install the ewelink software you can set the behaviour of the switches. Personally I don’t like depending on external servers so I replaced the firmware with Espurna – which you can Google easily enough.

      1. Hi Steve, I have managed to get one working perfectly, but the other two behave differently even when I use the exact same settings. Anyway I have about a third of my home lights automated, brilliant! I bought cheap just to get the knowledge and experience.

          1. Hi Steve, yes there are two switches K5 and K6 and the toggle S6 that changes between interlocked and inching. If I use exactly the same settings on all the units, K5 1111 K6 0100 and S6 1 they all behave differently. I have tried resetting, rebooting, deleting and re-installing makes no difference. But I am very excited to have taken the first steps towards automating my home!

            1. With that setting it should be in its simplest form – all relays self locking – the K6 switch should be ignored but it might be worth switching that to all zeros’s. Good luck with the rest of automation.

              1. Hi Steve, I managed to get all the Smart Switches working properly, I am just having a problem getting them all connected at the same time to the App. I am sure that with determination I will find the solution.

                  1. Thanks I will look at it. The Sonoff web site suggests that I use different WiFi connection for all the different controllers. That will be a bit painful but I will try, and if that does not work will try Espurna or Tasmota

  10. Hi i have two of these installed and were working great however i changed the router and now when i try to connect it as a new device and pair it again it doesnt work. Anyone have any idea how to reset the module and wipe what is currently stored on it?

    1. Hi Nayan, I had the same problem, especially if you edit the 4 CH Pro. I deleted them all and then had to re-add them, and edit. Once I had done this I went to my Google Home App and did the same, removed the eWeLink and then re-added it. After that everything was correctly configured, I just have problems getting all of the Smart Switches to connect at the same time!

  11. Hi,

    Did you find the information about pin assignment (433 receiver, button input, relay control outputs, LED, DIP switches etc.)? I usually reprogram Sonoffs (I did it for “classic”, dual, SV, 4CH) using Arduino + Souliss.
    Are they connected to GPIO lines or available via serial as in Sonoff dual? (I don’t like this approach, to be honest).

  12. Do you know if you can use Both Wifi, and 433Mhz control at the same time?..

    I am looking at having lights and a few other things controlled by Alexa in the garage, but want the redundancy of having a ‘physical switch’ of sorts as well for the lights.

    I guess there are ways to do this as per a normal lighting circuit, but would be handy to have the 433 control as well as alexa….

    1. Hi James. I don’t know the answer to your question re using 433 and WiFi together especially on replacement firmware but I get around your problem of the physical switch by employing 433 mhz wall switches which transmit their signal to an ESP8266 that has 433 RX and TX modules attached to GPIO pins and runs OpenMQTTGateway software (search on github) and then that translates the 433 switch signals from the wall switch to MQTT data which I use to update the same topic as the sonoff/similar …or use a rule in my automation system to trigger the on/off state from more than one MQTT topic.

      It’s a bit convoluted but seems to work ok and you can employ multiple identical OpenMQTTGateway devices around the house if you have problems with signal….that’s the only faff…2.4g/5g wifi networks give much better coverage than cheap 433 kit but a bit of experimenting with antenna trimming can make a big difference at both the RX and TX sides.

        1. Thanks DrFragle – I remember seeing that the other day. It would have been an option to consider had I not built several Wemos D1 Mini 433 to MQTT gateways using the OpenMQTTGateway code I found on Github. I might get one to play with anyway though, such is my addiction to new IoT toys discovered online…

          You’ve got to applaud Itead for their innovation and ability to bring so many cool IoT products to market – whilst leaving them open for people like us to replace the firmware in them with our own.

          Has anyone tried the Sonoff LED ceiling light. If so, is it cheap and nasty or does it look okay? The Slampher units (I have several) are a bit clumsy in size so I was considering other ready made room lighting options…

            1. Should’ve guessed you’d have one coming! I’ll keep my eyes peeled on here then and hold fire on buying one myself (I’ve got too much surplus kit lying around now – I need to actually use some of it properly!)

  13. Just to let you know that Tasmota version 5.4.0 now supports the Pro. (Couldn’t test as mine are still in the post.)

  14. Hi Peter,

    Any chance of getting a close up/hires photo of the board?

    I’m wondering whether this board would be a better candidate for adding a water flow meter, which needs 5V and a spare GPIO to sense the pulses.


  15. Dear Pete,

    I found your article about the Sonoff 4CH Pro very informative and valuable. The 4CH is A great device, but I share your view about some concerns about the power load A typical Sonoff device can handle in relation to the fuse current protection on board. I saw your cooments on this in the article for the 4CH Pro and I wouls also add separe fuse protection in the main line of 5-8 Amps, just for safety.

    Now about the other devices: Sonoff RF, Dual and the standard WiFi wireless smart switch. Do you know: do all these devices have a fuse on board? Is it also replaceble by a lower Amp fuse?

    And regarding the Broadlink SP3 or SC1, what’s your view on safety/fuse protection in those devices?

    Many Thanks,


    1. Hi Marc

      Well, most of the lower cost devices have soldered in fuses which really are not a lot of use if you don’t have a soldering iron or are not confident with messing around with high voltages. My comments here are general in nature, often, just as, when lamp manufacturers claim countless hours for LED light operation they are merely copying the specs from the LEDs themselves and the lifespan often bears little resemblance to the theoretical, we see these boards claiming 10 amps because that is what the relay is rated at. My advice would be to consider these values maximum load under any circumstances, not NORMAL load. So for example if you had a 2KW heating element, typically you can expect it to use 2KW – but that will be an approximate value, it could be slightly less, it could be slightly more… also when cold, such elements also take slightly more current… so all in all I would always add a margin. If a controller claims 10amp, ensure no more than 8 amps goes through it for example. You could of course (in the UK at least) add a lower value fuse in the plug – hence avoiding a situation of blowing a PCB fuse which might be hard to replace.

      Broeadlink SP3 I have no experience with this though they claim 3KW – personally I’d be putting my 2KW bathroom heater on that but not a 3KW bathroom heater for the same reason – the spec is too loose – is that working current – or is that maximum? I’d treat it as maximum under any circumstances – better safe than sorry.

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