220v 30 amp smart switch

I’m interested in hooking a smart switch up to my air compressor so I can turn the switch off from 10pm to 7am to prevent the compressor from turning on. I prefer WiFi (ESPHome or similar) over zwave, but I figure I can’t be picky for this. Does anyone know a good way to accomplish this?

The compressor is 220v 30 amp.

I suggest a sonoff basic or a sonoff 4ch / 4ch pro driving a contactor in your DB. You need the appropriate contactor, probably Ac7b. The 4ch sonoff can mount on a din rail or you can get a cheap din rail mount for a sonoff basic. Flashing esp home on these is well documented.

Do you mean something like this?

If I’m reading that right, it looks like the switching device needs to feed 24V to the contactor to switch it correct? So I just use a Sonoff basic to switch the 24V?

How do I wire this? Does my line feed connect to the 1 & 3 terminals and the feed to my compressor connect to 2 & 4? Does the Sonoff Basic connect to either A1 or A2 based on if I want Normally Open or Normally Closed?

If I’m reading that right, it looks like the switching device needs to feed 24V to the contactor to switch it correct? So I just use a Sonoff basic to switch the 24V?

An unmodified sonoff basic can only supply the same voltage it’s supplied with (110v or 220/240v)

You probably need something like this: https://uk.farnell.com/schneider-electric/gc4020m5/contactor-dpst-no-240v-din-rail/dp/2835299?CMP=GRHB-SCHNIEDER

Or possibly a three phase version?

Coil voltage availability is largely country dependent.

Local bylaws may apply of course…

I made a mistake on that contactor: it’s only a 15A device with an inductive load… But you get the idea…

You can do it like this

You can buy any relay with coil voltage of 220V.
Hook a small relay on an esp and let the small relay switch on the big relay.

I might be over my head on this idea. I get the idea with relays but I’ve always dealt with 120v or less relays with one hot wire. I’m getting confused on these 230v relays on what I need to trigger them. Presumably, I need a 30a relay that will take 2 hot wires and is “tripped” using a 110v input, then I can use a Sonoff basic to “trip” it, correct?

What is your countries voltage?
To greatly increase simplicity, all components should to be for the same voltage (besides the DC of course).

All relays (actually all electronic devices) work with two wires: phase/neutral (AC power) or +- (DC power). I’m going to go with AC here since that’s what’s typical for 110 / 230V.

A contactor or relay normally has 4 contacts: 2 for the load (in / out) and 2 for the control contacts: phase / neutral.
So working back from your compressor: its phase wire (from the wall plug) needs to connect to the “in” contact of the contactor, its neutral goes to the “out” contact of the contactor.

The two contactor control inputs: one goes to neutral (110/230V).
The other depends on your device:

  • Sonoff: it seems it can handle 90-250V. So just connect its output to the control input of the contactor.
    -Generic ESP/Arduino/whatever: this needs an extra relay. Let me know if this applies.

I must say, since you seem to not have experience in this field, ask a friend or someone who does. It’s not only about how to wire it up but also the wiring needs to be done properly. 30A is a LOT of current, badly wired cables will give you more smoke effects then you wish…

Disclaimer: I’m not a certified electrician and all info posted here is for the risk of any reader, I take no responsibility.