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Sonoff Safety Concerns

I'm really concerned about the safety of the Sonoff devices. 

These photos show a TH-16 unit that was fed from a 13amp fused spur (240V) and feeding a 3kW fan heater. Total load was less than 13A, yet this is the second Sonoff that has self-destructed in 4 months. Although there has been a recall for the PCB track tinning, I believe the fault is with the fuse clips. That is where the charring of the board is the worst - the board has literally melted and the fuse bent over to touch the terminal block (by gravity). 

What is the rating of the clips? Schurter of Germany make some of the best, and they are only rated at 10amp (…/fus…/dp/1453528…

Until this is sorted I am only running heaters on half power, and am tempted to short out the fuses, as they are protected by a 13A fuse at the spur.





Hi, I have just experienced the same problem with my TH16. In my case I was running a water heater rated at 3kW, 230V, I measured current independently at 13A. In this use case, the system as set up was operating for at about a month, and typical operation was relay open for 20 hours out of 24, and closed and under current for about 3 hours.

The TH16 date code appears to read 2017 - 2 - 10 but is partially damaged. 

The unit was mounted sideways against a water cylinder, and there was almost nothing left of the fuse. It appears to have melted and burned a hole through the side of the housing on to the surface below, which is where I found a lump of solder mixed with glass and the remains of the fuse holder ends.

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I have just had my 3rd Sonoff fail - again driving a heater. This one was only 2kW (230V), so way below the 16A rating. It also shows that it is the fuse clips that cause the problem, not the PCB tracks. The heat from the fuse/clip junction conducts back to the PCB and melts the solder under the clips.

I will be soldering a 2.5mm copper link across the fuse clips from now on. They are just not fit for purpose.

I am also concerned that there has been no comment at all from Itead on this matter - don't you care guys?





Looks like itead have listened - have a look at the new dual Mk2:

They are using a solid link to replace the fuse!


I blew the fuse on a Dual and need to replace it.  There are no type designations on the fuse can someone tell me what they are other than 12A 230V?  Such as AGC, AGM, neither of which is right for this unit.


Version 2 of the PCB now has the fuse back. Oddly mine burnt out now around the bridge rectifier and a component linked to the voltage regulator. At least this isn’t as dangerous, but it is still very odd. If only tech support had any interest.
Hello guys, I saw someone over YouTube using a contractor along with a Sonoff device. The contractor will handle the big current separately so that the Sonoff won't have to deal with the high amperage.
Hi. Isn’t the fuse is supposed to protect the item? With the fuse removed, is it a safety concern?

Can anybody confirm if the units which are failing are V1 or V2 boards and any indications as to whether the issue has been addressed?

I'm running a 2.5k heater from a TH16 (albeit for very short bursts, 5 minutes at a time maximum) but am very concerned to see examples of these switches failing like this.

Mine that failed was a MK1, but it was nothing to do with the high current part. When I actually opened it up the fuse was fine, but the bridge-rectifier had burnt out. Itead support was typically useless, hence why I actually opened it up myself and had a look.
Thanks EB. I can only hope the high current failures earlier in the thread have been fixed in the R2 boards.
Dear Friend.,
My Sonoff TH was lost signal yesterday morning.
At night I try to check 


my wifi network are fine only Sonoff th not working from 30 Sonoff devices. That one was used for control Solar collector Heater that 1000W and working 8:00 -10:00 am and 5:00 - 11:59 pm. When (if) water is cold than 40 C. Some thing was wrong I went to check at roof deck I found it burn and not only me found this problem. Here is references Please improve your socket that safety enough or match on power spec. That is safety concern. However I will add magnetic contactor (relay) with Sonoff TH in Solar collector.
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It is well known among people in the hobby that SON SOFF was never designed to handle such devices. The relays are likely not rated for it the traces are not rated for it there is no UL or any approval and the reason is not because it costs money the reason is because it simply is not designed for it!

Will it control your lamp yes within reason pay attention to loads I propose that a load of no more than a few amps be used on these boards they are way over rated. I would only trust them with a box fan low powered or a single LED bulb lamp stuff like that.

For something large you will need a power switch tail or something like an OMRON relay or I have a friend named TrackerJ "Nickname" that runs an electronics outfit out of Romania stand up guy he will hook you up NextEVO is his company.

You will pay a bit more but at least your kids your dog or you will not die in a fire.

This is a huge hazard and it is well known already don't bet the lot on SON SOFF or similar these cheap relays are always over rated even the ones that say 10A max are not meant to run at 10A continuous MAX ratings are never to be assumed that you can run something at that rating 24/7 and everything will be AOK! 

What relays are there did you check the datasheets?

Finally do not trust that those traces were designed to handle 16A of current! Not even close for any extended period of time.

Another issue people have had with SON SOFF is the way that they hook things up there is a right way and a wrong way electrodragon was selling similar modules a couple years back be aware of these things this was a warning do not bet the lot or your lives on these things not worth the time and effort saved.

I've had the same issue with a TH16, running a water heater. In my case the problem was the push connector generating heat and melting the connector. I fitted a contactor and that works well - except I can't use the power measuring circuitry. So I might as well have bought a cheaper switch in the first place.

Conclusion - they are not designed for heavy current use, whatever their ratings.

This is correct! Hope people even stop trying to use this improperly. It is folks who do this kind of stuff and openly share it which will start forcing regulations on these things next which would be not the most ideal of situations for the hobby. In theory it should be safe due to ratings but never believe that without some type of underwriters laboratory certification. 

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