Net metering and switching of equipment via relais

Questions & Help
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1

Hi everyone,
I am wandering if the new Homey Pro is capable of following:

I have a 3x25A mains connection and a 10.5kW 3 phase sauna. I want to prevent the main breakers to switch off when the total consumption of one or more of the phases exceeds 25 amps. If the 25 is exceeded, the corresponding phase(s) of the sauna need to be switched off with a relais.

I probably need a 3 phase current meter and 3 relais that can connect to Homey.

If the above is possible, how fast would the reaction time be? It should be in the milliseconds area.

Reason for not upgrading to 3x35A is the yearly extra cost of 700-800 euro.

2

This all sounds like a bad idea, and I wouldn’t rely on any home automation platform for this.

3

Hoi!
Actually suspecting, the automation in such way may be not possible. The circuit breakers are anyway faster, than the “Homey”.

BUT… You do not described the “other things”, which ones may cause over-current. If there are (one-two) devices, which ones act predictable, then it’s sufficient to check them, and if they start, switch off sauna. For example in my own house the washing machine is such predictable device. If it’s consumption rises above 3W, then it’s clear that someone switched it on… and after some minutes it’s usage can rise above KW’s ( good time to switch off boilers - they can held hot water anyway during the washing cycle).

Another, not so fancy thing is to use Priority Relay’s - Something like this (first google for “priority relay switch”)

1 Like
4

Thanks Cuprum,
The other devices are general household equipment like:
Oven 3.6 kW
Induction furnace 11kW 3 phase
2 airconditioners
Car charger 11kW (load balancer, so should be no problem)
Quooker 2kW (water heater)

I will look into your suggestion.

5

Thanks Robert, that makes sense.
Any suggestion for a solution?
Like hardware to install in my electric cabinet?

6

The suggested priority relay sounds like a good idea. Since you’re going to need an electrician for installing it, you could also ask their opinion on how to deal with devices that require a large load.