ESP8266 DIY Smart Socket (2017) | Hacker News Reader

ESP8266 DIY Smart Socket (2017)

notenoughtech.com

41 pointsstacktrust57 comments

I like the enthusiasm, but you REALLY shouldn't be DIYing this. This project is almost certainly violating half a dozen safety standards which exist for a very good reason.

Don't toy around with mains voltage - especially when an off-the-shelf solution is widely available for less money. A Sonoff smart socket is only $15, and you can even flash your own firmware on its ESP8266. All of the benefits, none of the "accidentally setting the house on fire" or "giving yourself a fatal shock"!

> I like the enthusiasm, but you REALLY shouldn't be DIYing this.

Of course you should be, this is hacker news after all. But this guy shouldn't be because his soldering skills are atrocious.

At least he put a big fat warning on the article. I've built a 15 KW solar installation here and it's safer and better constructed than what your typical professional around here delivers. DIY electronics and working with mains are perfectly ok. I've been doing so since I was 12 or so and I really don't get this kind of alarmist attitude towards electricity, it isn't magic.

A hobbyist can definitely do the proper research and build perfectly safe high-voltage / high-current installations, no doubt about that. Electricity is indeed not magic. The key part here is knowing what you are capable of, and more precisely knowing where your limits are. However, it is quite obvious that this person has not done the proper research, and their work is held together mostly by hopes and prayers.

The problem is that random people on the internet see "guides" like these and treat them like an Arduino project: just something to mindlessly copy in a spare Saturday afternoon, and the worst that can happen is that it won't work. They will not do the research, and they will not take adequate safety precautions - they never had to do so before and they never had any issues, what's the big deal?

That's fine with most DIY projects. Heck, it's even fine with most DIY projects involving mains voltage - a guide for installing an outlet will always tell you to turn off the breaker first, at which point it really isn't all that dangerous. You're just plugging some pre-made and known-to-be-safe parts together, it's less complicated than building a computer. You have to actively try to screw that up.

This is a different beast. You're building a new thing which is handling mains voltage out of the cheapest parts you can find. You can totally do an Arduino-like project with that mentality - the average Arduino project going horribly wrong will result in a brief spark and some nasty smoke coming out, it's no big deal. But a project like this going wrong? It will set your house on fire.

Likely interesting note: Mains voltage is not considered “high voltage” in industry (minimum 600 volts AC, but higher under many standards [1000VAC per IEC]).

Mains voltage is “low voltage” in an electrical industrial safety context.

Mostly agreed but:

> But a project like this going wrong? It will set your house on fire.

No, the most likely outcome is that it will either cause a breaker to trip or that it will simply stop working. 'it will set your house on fire' is only one of the three possible outcomes and the least likely one. It can happen though and that's why this guy should be doing his stuff for himself rather than broadcasting it to the world because the final product isn't 'good enough'.

Apropos Sonoff, the brand you advertise in your original comment: they had a pretty serious issue at some point where they had a fuse in a holder inside the devices that got excessively hot because it wasn't rated for the current of the socket. And that is a fire risk.

https://www.reddit.com/r/homeautomation/comments/as26oj/sono...

> It can happen though and that's why this guy should be doing his stuff for himself rather than broadcasting it to the world because the final product isn't 'good enough'.

That's exactly the point I've been trying to make. Of course "it WILL set your house on fire" is an exaggeration and other failure modes are far more common, but the fact that it is even a remotely-possible-but-plausible outcome means projects like these shouldn't carelessly be shared with the general public.

Yeah, I mean that is indeed the most likely outcome. If there is the proper breaker installed, the wires are wired in the correct way, there is no lightning-induced power surge, etc. The idea of electrical safety rules is to reduce catastrophic consequences in unlikely scenarios. This way we drove down casualties.

As a certified EE I totally support your warning.

The problem with mains voltage hobbyism is that it is really easy to build something that works fine in 99% of the situations until it encounters those 1% situations that the hobbyist couldn't plan for, doesn't have the knowledge of, doesn't has the tools for etc. The problem with that is, that if you're unlucky it can literally ruin multiple lifes at once.

Experimenting is one thing (know the risks and go ahead), but putting things out there in circulation is an entirely different can of worms. I had to learn all of the VdE rules and many of them have been written in catastrophic failures and house fires. And I thought I knew a lot when I started learning those rules, and oh boy was I wrong. All electrical appliances interact with your house wiring, and there can be very weird fault conditions between your appliance and your house wiring, that are very hard to predict (and even harder to test for) by a "electricity comes out of the wall"-hobbyist.

But how would you know if your work is better (and safer) than what a professional delivers? The professionals, in theory, have more experience and more knowledge in depth than an amateur; and if an amateur has greater knowledge than a professional, is he really an amateur still? Of course, some things might be obvious to an amateur or a lay person (walls not straight, for example), while others might be more subtle and deadly at the same time (foundation issues).

> DIY electronics and working with mains are perfectly ok

That's great to hear! Now let me connect this beefy microwave oven transformer to the mains and do some electrical wood burning, surely it will perfectly ok

> But how would you know if your work is better (and safer) than what a professional delivers?

Common sense?

> The professionals, in theory, have more experience and more knowledge in depth than an amateur; and if an amateur has greater knowledge than a professional, is he really an amateur still?

An amateur is someone who doesn't do what he does professionally, a professional is someone who makes a living with the thing they do. That doesn't say anything about their knowledge level. But when you're a professional and you claim that you are 'done' with the installation and I spot: a HV DC wire pinched between a panel and the mounting rail, a HV DC wire (the + terminal) run through the cooling ribs of the inverter (sharp af near the ends) and a mains cable whose connectors aren't torqued down to the point that I smell ozone then you have to wonder. Note that there is a distinguishing factor with solar installers: they are not afraid of heights. Electrical knowledge is apparently secondary.

> Of course, some things might be obvious to an amateur or a lay person (walls not straight, for example), while others might be more subtle and deadly at the same time (foundation issues).

The above are a mix between obvious and non-obvious but those guys probably did 400 installations last year and if my n=1 sample is any indication then I wouldn't be surprised if they left some latent problems behind them.

> Now let me connect this beefy microwave oven transformer to the mains and do some electrical wood burning, surely it will perfectly ok

If you insist on being stupid then I don't think that's a fair way of conversing here. You can use common sense, read the electrical code (though it's an expensive book, which is kind of weird, you'd expect it to be free) and you can get yourself some basic knowledge about electricity and electronics all the while doing nothing more 'scary' than using batteries or sitting on the far side of an insulation transformer.

If and when you feel ready for it you can switch to mains powered stuff.

The scariest stuff to work on: old fashioned tube based color TVs but I haven't seen any of those in a couple of decades. Other than that, I would be very careful with a microwave because it is probably easy to create a radiation leak and I don't have the proper gear to detect one. So I'd stay away from that. Again: common sense.

> Common sense?

Unfortunately common sense isn't as common as you'd hope, and there are plenty of things which are "common sense" among amateurs which are simply untrue.

> An amateur is someone who doesn't do what he does professionally, a professional is someone who makes a living with the thing they do. That doesn't say anything about their knowledge level.

Professionals usually also have formal training, which means they are at least somewhat familiar with the theory behind what they are doing. PV installation is indeed a well-known cowboy industry right now, but I can assure you that an actual electrical engineer will be way more capable than a random hobbyist when it comes to actually designing electronics. Your one experience with a single PV installer does not scale to the entire industry of electronics.

> I can assure you that an actual electrical engineer will be way more capable than a random hobbyist when it comes to actually designing electronics.

A randomly chosen EE better than a randomly chosen hobbyist? Sure.

A randomly chosen EE better than all hobbyists who’d be inclined to take on such a project? I seriously doubt it.

> an actual electrical engineer

An actual electrical engineer is unlikely to have the necessary certification to do electrical installation work for someone else. What you want is an electrician.

The point is that what's common sense to an engineer is different than what's common sense for a lay person or an amateur. Their way of thinking is different. A lay person is not aware, doesn't know and can't mentally model the kind of power a microwave transformer can deliver: it's almost (almost!) an out of context problem for them. They just saw the pretty fractal wood burnings on tiktok and want to try themselves. And then they die[1]

That's the point of all the scary warnings, caveats and reminders. They're there for not-engineer-minded folks, so that they don't hurt themselves or set their house on fire.

[1] https://en.wikipedia.org/wiki/Fractal_burning#Safety

> You can use common sense, read the electrical code (though it's an expensive book, which is kind of weird, you'd expect it to be free)

NEC is free (as in beer) online: https://www.nfpa.org/For-Professionals/Codes-and-Standards/L...

It’s a slightly cumbersome site, but functional.

Common sense is rare.

Just because you don't trust yourself with mains power doesn't mean every hobbyist will burn their house down.

I disagree strongly. Safety should be adhered to and reminding him/her even once too many times is the right thing to do.

BUT a lot of things are dangerous, and we can become proficient at it. Driving a car is helluva dangerous but we can learn it. You can learn about mains voltage, and you should learn about it properly first.

But to suggest that one not try to innovate like he does - then hackernews is not the right place for your nerves :)

Honestly, I think the guy first needs to learn how to solder properly. It looks like a mess.

Indeed, that's the biggest gripe I have with this project: shoddy execution. The way the wire insulation has been damaged just makes me cringe.

I'd be more worried about the 2A solid state relay, seems way underspecced for a typical 10/16A plug.

True, especially if bought from Aliexpress, Amazon, Ebay or similarly unreliable source: most solid state relays sold there are relabeled fakes claiming higher specs than their actual one.

https://protosupplies.com/inferior-counterfeit-fotek-ssr-25-...

https://www.eevblog.com/forum/reviews/warning-dont-buy-fotek...

Buy parts only from reputable sources, especially when safety is involved, which is the case with everything that is connected to mains voltage.

Have a look at what is inside a typical blister packaged smart socket and you'll never use one again.

I've used tasmota pre-flashed Athom 16A smart plugs with discrete success. According to this video https://www.youtube.com/watch?app=desktop&v=FWQe4RFgY1s at least the relay is the proper one and wires seem beefy enough.

Unfortunately they tend to die prematurely for some LVDC regulator problem.

Both the relay and the wiring in that particular smart plug looks to be up to spec, going by the markings on the relay and the apparent wire thickness. At the end of the video he does an insulation test as well and it passes with room to spare. There even is a basic surge protection in there (the big blue disc). I would have liked to see the circuit board airgapped between the HV lines to reduce the chance of creep if it ever gets humid, but for dry applications indoors this should be ok. I didn't see a fuse and I would have liked to see a small inductor to separate the HV from the LV section but that's expensive so many brands choose this kind of directly coupled system. R1 (the high wattage resistor next to the relay) and the two 400V caps are doing the heavy lifting there and even though that works I just don't like having electronics directly coupled to mains voltage. The 'Sonoff' devices do this better.

I've done a similar teardown on KaKu, Tuya and Shelly products and only the latter were - in my opinion - acceptable from a mechanical and electrical design perspective. The Tuya stuff was absolutely terrible (and required a server in China to have access to stuff in my home which will never happen), the KaKu ones are confusingly labelled (but if used at the lower of the two labelings probably safe) and much lighter in construction than the website suggested. The Shelly stuff is simply solid and comparable to the one in this video and doesn't require any cloud services. So that's what I went with. Bonus because it integrates seamlessly with HA.

I had the same plans, and then came to the same revelation that not only would I be violating a bunch of rules, but I might void insurance and take on liability for a whole bunch of houses in case of fire, even if my shoddy work didn't start it.

As a compromise, I got a bunch of radio controlled plug-sockets, and started on hooking up a 433mhz transmitter to an esp8266, and....... well the transmitter stopped working once I soldered everything down and I then got distracted by other shiny things. Been meaning to go back to it ever since.

I recently had a conversation about this, and someone said this:

"The graveyard is full of people who knew what they're doing"

@jacquesm nailed it. I will just add that a competent DIY enthusiast will be able to design a better and safer switch than those cheap ones you find online, not least because they are probably not trying to cheap out on everything.

beh. these aren't high voltage transformers or anything. you can buy diy "mains voltage" equipment at any hardware store. no one is shouting from the rafters "you REALLY shouldn't buy that!"

Correct, but those are pre-built parts which have been certified. They are designed to be safe, even when mildly mishandled. Plugging in a toaster or installing a wall socket is indeed pretty safe.

In this project, on the other hand, you are building something new which will handle mains voltage, using the cheapest parts you can find on AliExpress. It's not designed to be safe, and it's definitely not certified or even tested. That's not something you should do without doing a loooot of research first.

> you are building something new which will handle mains voltage, using the cheapest parts you can find on AliExpress

This seems like an invented argument.

Many relays you find on amazon and similar marketplaces are CE or likewise rated.

Add a quick blow fuse to the circuit if you are skeptical of the thresholds.

I would also say if you sat through a primary school science curriculum, it doesn't take a "loooot of research" to understand the basics of residential electricity. Fifteen year old students learn it in vocational technology courses.

> Many relays you find on amazon and similar marketplaces are CE or likewise rated.

The tutorial got them from AliExpress. The links are long-dead, but if they have any ratings they are almost certainly fake. Also, CE ratings apply to finished products - they don't make sense for individual parts.

> Add a quick blow fuse to the circuit if you are skeptical of the thresholds.

... which the tutorial didn't do.

> I would also say if you sat through a primary school science curriculum, it doesn't take a "loooot of research" to understand the basics of residential electricity. Fifteen year old students learn it in vocational technology courses.

That's the problem: this isn't basic residential electricity! You're building a new device, without all the mandatory safety precautions you'll find in off-the-shelf products. The most dangerous part is that at first glance it looks fine, while it's actually violating some quite basic design rules.

> Also, CE ratings apply to finished products - they don't make sense for individual parts.

UL and CE guidelines definitely apply to things like relays, bulbs, wire, etc.

2a relay does not look like a good idea unless the socket is marked appropriately and fused to suit as well.

Mains electricity is ubiquitous so we tend to think it's safe. It really isn't, and electrocution and fire are both real hazards, only uncommon due to good safety standards.

Typical store bought smart sockets are 1.5A and have a lighter relay in them than what this guy used, note how his goal was to be able to remotely switch chargers on and off. They are also 'marked appropriately' in type that I need a magnifying glass for to read. I've seen people control way heavier loads with them without being aware of what the ratings on those things are because the labeling is nothing short of confusing. I just took one off the shelf here to check and indeed it says 16/250 on the front but on the back in tiny type it says max 250W and 1.136 Amp. With a prominent CE mark between the prongs (this is from a brand with a reasonably good reputation).

> Typical store bought smart sockets are 1.5A

That sounds like a raw deal, just off the top of my head:

Shelly, 12A - https://www.shelly.com/en/products/shop/shelly-plus-plug-s

Local Bytes, 13/16A - https://www.mylocalbytes.com/en-eu/products/smart-plug-pm

Sonoff, 10A - https://itead.cc/product/sonoff-s26-wifi-smart-plug/

Athom, 16A - https://www.athom.tech/blank-1/esp32-c3-eu-plug-for-esphome

(Most of these have US equivalents)

> this is from a brand with a reasonably good reputation

Please name them.

> Please name them.

KlikAan/KlikUit aka 'Trust Smarthome', socket type ACC-250-LD, it's a 250 W remote control dimmer socket but on the front it is labelled 16/250 which for lay people would probably be highly confusing because it refers to the plug, not to the capacity of the device. The small print on the front of the plug part (so unreadable once it is plugged in...) is where the 1.136A rating is specified. Such small mistakes can have big consequences. A nice fat 250W MAX rating stamped on the socket side (black is fine, but red would be better) would go a long way towards dealing with my irritation about this stuff.

That's due to it being a dimmer, which probably uses a triac or other semiconductor component for switching. The mechanical relay types are more popular and higher current.

Absolutely, but that's not an excuse for their shoddy labeling.

I would use a real relay to switch line voltage power, like one of these: https://www.functionaldevices.com/product/ribu1c/

It has a 10-30v (and 120v)control coil so you can use a low voltage circuit to control it.

Those look pretty serious.

Switching line voltage current is serious, I’ll take an enclosed relay with a UL listing over an aliexpress special.

This one is more suitable for use with an ESP8266, it has a pair of dry contact inputs and switches 120v-277v that could be triggered with GPIO: https://www.functionaldevices.com/product/rib01bdc/

I'll keep those in mind. I do this sort of thing all the time and I ended up building a custom ESP8266 unit to switch my heater on and off based on a bunch of remote thermometer readings in the house. The decision is a bit tricky: keep the pump running but the heater off to spread the heat more evenly or to fire up the boiler as well. So with some HA scripting that works super reliable but from a hardware perspective it could still be improve on and your supplier looks like it just what I was looking for when I was building this but couldn't find something suitable.

Thanks!

What I'm most afraid of about some smart sockets is that I can find various weird brands of them on Amazon, looking exactly the same, rated for wildly different amperages.

Yes, that's super annoying. They should be clearly labeled on the device as to what their max capacity is (and you should then stay well below that to give you some margin).

They are! I have two of them, both look identical, work the same, and have different ratings on the device. They may be true, but can you risk it?

Inquiring minds want to know. Time to break out that amp meter and a nice fat load and do some testing.

Surely I can make do with a variable load and fire extinguisher.

Hehe. Ok. Be sure to have multiple cameras running :)

And to stick a thermistor on the distribution panel breaker just to be safe. Those things don't like to be slow cooked.

If the pins of the relay were insulated with heat-shrink and everything soldered + mounted nicely, this project would be more passable. In its current state it honestly seems like a fire hazard.

Maintaining 40+ smart sockets was getting truly messy. Mostly I needed master switch to turn them all off. So eventually this evolved into this here touch-button master switch, with PIR-sensor for detecting sleep or absence (or death). https://github.com/timonoko/Hipaisunappaimisto

Edited Google-Translation:

Touch remote control ESP32

The previous everything control was a bit crap when the keys fell apart. K-mart had nice chrome pins, from which I made a 21-key controller, where the keys are primarily read via the MC14067 analog mux.

This does not require an external server, as "urequests" seems to work quite reliably, but only in one direction.

There is also a 433 Megahertz transmitter here, so Lidl's 10 euro plugs can also be controlled, and Wi-Fi is not always needed.

PIR sensor added, it turns off unnecessary devices if no movement has been detected for an hour.

Apropos. I repaired the micropython "urequests". So it now works both ways. Somebody was not happy with this fix, but did not suggest better solution. https://github.com/timonoko/t-watch-2020-micropython-hacks/b...

No pull down resistor on the relay? Hmm.

What would you use a pulldown resistor for in this case? That SSR has a must-release current of 1mA. It isn't a FET that can charge up with micro/nanoamps until it turns on.

I thought this was a web socket. Then I clicked the link and saw it's a wall plug! Lol

npm install burn-down-the-house

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