When I was mining Bitcoin with 240V equipment I was obsessively careful not to overload any component. That entailed knowing the rating of each device in the circuit and not running it above 80% of that for more than 3 hours straight. I also bought everything certified and stayed away from Chinese junk. In years of running 24/7 had 0 problem. That’s why high performance electrical equipment in US usually has the max load marked as “Agency Derated”, which means that the value indicated is actually 80% of the max load.
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Its simplier to say than to do. Dont buy crap and you are safe.
How can i know does the hardware i bought is crap or not?
Who prevents any company based anywhere to make faulty devices made of cheaoest parts there is?
The only way is to see does some device is good or not is to use it.
We once bought a brand new Chrysler. Car had serious brake issue from the factory.
Thankfully no one was hurt.
Did Chrysler was responsible for this? No. They done the exact same thing as soniff did in this case. We will give you a new switch/brakes and call the day off.
As for manufacturer reability goes you can forget about it. Theoretically they can be held reliable but in great majority of cases they wont be.
And as for chinese crap goes never had an issue with it. Except this one aquara switch that was burned down due to high voltage.
But as i mentoon earlier probably the easiest way to prevent this will be a sensor in ha that measure device temp as it can be done on esp32 boards.
I
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Best you can do is check the reputation of the manufacturer, use the device as per their guidelines and employ some preventative or detective control like a smoke alarm with the ability to detect fires even in the incipient stage.
My limit is 75% of the rated current capacity of any smart switch. Even then I would consider using a contactor (relay).
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This is somehow my opinion on it. Install it use it, check it from time to time. You can feel if the switch our outlet is warm or not.
But again I think that temperature sensor per device will be long term solution. Maybe this could be done on all existing devices out there by firmware upgrade.
Code in the EU is that all certified electrical equipment (outlets, switches, etc) have to be rated for continuous 100% load. Wires also have to be sized for continuous 100% load.
I am not sure how this applies to smart devices. Technically, it would be the same. If you look at the ridiculously thin traces on the PCB supposedly being able to ‘safely’ carry 16A or so, and the suspiciously puny relays, uh, no way. Especially on some of those Chinese junk devices. I’d probably use a derating of 50% or more on that stuff and still not feel safe. A few LED lights, maybe 2 or 3A max. Anything above that → contactor.
And even that would not have prevented the burning in the OPs case, as his plug bbq’ed itself without any load at all.
Oh. I just ordered two sonoff devices, the ZBminiL2. These will be mounted behind wall switches, so very much out of sight. Seeing this scares me quite a bit.
I did some googling, there’s quite some stories about the POW switches burning but I don’t see ZBmini devices show up as fire hazard. Anyone here who can comment on that (they have CE and TUV certificates but as has been mentioned, these agencies don’t do regular samples to check continued compliance.
Same company, same quality control. Your call.
Fair enough. I decided to get these because I have the zigbee dongle and it works very well. But power electronics is a different game altogether of course.
CE is often wrongly taken as a kind of certificate - but it isn’t. Strictly spoken this marking was not even intended for consumers at all.
Regarding the value of TUV certificates - any one remembering that huge water dam in brazil which bursted only weeks (or months?) after certificated by TUV?
In the end the EU doesn’t have anything equally to UL for example - which can be good and bad. Typically it’s good in case a damage happens as insurance companies can’t say your device wasn’t XYZ marked/certificated so we don’t pay the damage. The bad part obviously is their is no common ground customers can choose their device to be assured to have a basic/minimum quality.
In the end probably 99% or more of our devices are produced in China. The good, the bad and the ugly.
Stop with the unsubstantiated Chinese bashing. Show me ONE electronic product not made in China or with parts from China. Just one.
That’s not true. It absolutely acts as a certificate (but it’s more than that). The problem is that it is a self-declarative (but still according to a strict rule set). Non-compliance is then handled case by case by the courts if something happens. Another problem is counterfeiting. Quote from the official site of the EU commission:
By affixing the CE marking to a product, the manufacturer assumes full responsibility for its compliance with all safety requirements. Unfortunately, due to counterfeiting or the misuse of CE marking, there is never a 100% guarantee that a product bearing the mark is safe.
Yeah, I know about the CE marking not meaning too much. TUV does do some sort of testing though, don’t they? I know there is a Dutch agency for things like these (Kema) and their testing is actually quite extensive. My mentioning of the certificates was in reaction to a few people pointing out that the device in the start topic was not certified.
That’s not the point. Read my posts above. The problem is not the location of manufacture. It’s the problem about legal liability.
The point is not China’s huge manufacturing footprint but the astronomical amount of ultra-shoddy, cheap products they make.
If you pay TUV they test obviously everything for you. The important question to ask is what they test - for example what tests were done for sonoff? I guess whatever they tested (and were certified for) it was probably nowhere as strict as what a UL certificate for consumer elecetronic requires.
The certificate TUV issued for sonoff should state what tests were done and what norms (often EN in EU) the product complied with.
A certificate I can give to myself! Great fun!
It has close to zero meaning / value in reality for private individuals.
See the smoldered sonoff from @JoFranke - the E from the CE marking is still visible!
Well you could just say
And it would be still vaild.
They just produce almost all products - specially if they contain any electronics.
Let me requote the EU and emphasize the important part:
By affixing the CE marking to a product, the manufacturer assumes full responsibility for its compliance with all safety requirements.
So yes, you can give it to yourself if you think you are compliant. And by doing so you assume full legal liability if you’re not. But that doesn’t work with Chinese manufacturers because it’s legally unenforceable there.
They tested according to EN 60669 , which I guess is the correct norm if I read the description
That’s a Chinese manufacturer using a counterfeit CE label… Jesus, how often do I have to repost this 
The problem with Chinese manufacturers is that legal liability cannot be enforced.
Conculsion: don’t buy cheap Chinese junk.
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