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Comment by djaychela | Hacker News Reader

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.

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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.

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