Automation cpu/ram intensity

[sullen kelp]

Hi, I have a generic question about automations. I have some smart plugs to measure power and total energy, for the fridge freezer etc.
I don’t want these plugs ever go off, even by accident by my kids or when I click the button in ha.
I can easily make an automation: if plug freezer = off, then turn plug freezer on.
But how intensive is this for ha? This means it checks the value of the plug every second? Millisecond? Or how often does this value get checked? I’m trying to learn what the best way is to set this up. With kind regards.

[cloud warren]

you should instead get a smartplug without a relay in it.
fridge/freezers have a compressor which is an inductive load so you ideally don't want that on a relay anyway.

what country are you in?

[sullen kelp]

Netherlands.

[lament maple]

you'd not be the first person here reporting how they had to throw away all their food because the plug failed

[sullen kelp]

Oke, i get the point. But back to the automation, is there a best practice? Want to learn.

[cloud warren]

I think this is the right plug type for you? https://www.athom.tech/blank-1/no-relay-consumption-monitoring-eu-plug-for-esphome

[lament maple]

OH NICE!
thank you @cloud warren that's exactly what I was hoping someone would invent

[brave canyon]

Ordering a bunch of them...😍

[cloud warren]

if you were to do it with a time based automation that checks then sets if needed I would probably only bother doing it once a minute or something.
if the power was off for 1 min its not going to ruin anything realistically. there is a certain level of practical necessity.

athom also make a version of it that comes with tasmota instead of ESPHome if you are so inclined. however I prefer ESPHome.
they also do no relay versions of other plug types for anyone else that is curious from other places 🙂

[sullen kelp]

Im using Inspelning smart plugs (zigbee) for it.

[cloud warren]

in general I don't really recommend using any device with a relay for inductive loads as detailed above.
if your just worried about someone messing with it in HA itself then you can also just disable the switch entity for the device.

[lament maple]

@cloud warren I know and understand the issue with inductive loads in general
correct me if I'm wrong but isn't that mainly an issue when you plan switching the relay off while the device is running?
the motor works as a generator in that case which can cause high voltages resulting in sparks over the relay
if the relay is being pulled all the time there shouldn't be an issue or am I missing something?

[cloud warren]

in an ideal world then yes you are mostly right. however there are various situations where we are not in a ideal world.
the magnetic field from AC power can sometimes disrupt the magnetic field of the relay and if/when that happens you can get resets or even "rapid switching" which is obviously bad. given random noise and an infinate amount of time this will happen... will it happen in the lifespan of the device to you and actually cause harm... who knows. but its possible. also if this did cause an issue and lead to fire and home insurance decides its your fault you suddenly find yourself down insurance and without a home.
relays can also fail.
maybe the power chip for the esp and relay control fails and starts rapid reseting causing rapid relay switching...

some people will be all "I have done it for years without a problem" and whilst they might be right there is definitely an increased risk by doing it. this is why I recommend against it.

also if your never gunna want to switch anyway then there is no need to have a relay which is a point of failure no matter which way it fails.

if interested the plug linked above is almost identical to the normal smartplug its just on the board instead of fitting a relay they fit a bridging bar between the terminals. then just dont have the relay switch in firmware.

i think it even still has the button but it doesnt do anything. although then you have a detached button which you could automate other things with if you wanted because a button is a button 😛

[sullen kelp]

I’ll get myself 2 without relay. Just in case 🙂

[cloud warren]

yup, that solves the issue 🙂

[brave canyon]

Ordering 4 of them... thanks one more time 😉

[lament maple]

absolutely true
I was not aware of that athom offering

I am using a plug with a relay on my washing machine and dishwasher
I've configured home assistant to cut the power when it detects a water leak in that room, but in general everything you said makes sense and I'm considering to switch both to the athom devices

[cloud warren]

I've configured home assistant to cut the power when it detects a water leak in that room
whilst conventional wisdom would see this as a good idea. if its on switching it can cause arcing the weld the relay in the on position anyway. so you shouldn't depend on this.