Which smart plugs (or smart tags) to use to monitor 10 devices' uptimes

I have a small factory type setup with 10 extractors. They are basically heating elements. Right now I have each socket wired to a timer in a wall-box. Not relevant but each socket has it's own circuit breaker.

Sometimes the extractors have a fault and stop heating before the time set with the timer is over. I have no way of detecting this, if I don't check just before the timer should finish. This is not ideal, as the product is defined by the time it was extracted.

My initial plan was to install resettable sub-counters on each line before the timer, so the operator checks in the end of the cycle if enough kWh have been used. A bit cumbersome.

Schneider has these smart tags (ie A9MEM1561) but it would be quite expensive in total, as one would also need a gateway if I understand correctly. Maybe there are other similar solutions?

So maybe I could just use smart plugs?
I'm looking for suggestions for reliable smart-plugs that work nicely with Node-RED. The limitation is that the sockets are powered with the timers and I am not looking to change this behavior, for this functioning is already codified and integrated into the documentation. So when timer turns the socket off there's no current for the smart plug either.

Sometimes I use all 10, sometimes only 1-2 extractors at the same time.


Personally, I wouldn't want to rely on consumer smart plugs in a commercial environment. The weakness of a smartplug is typically the relay and I see these fail relatively regularly.

Depending on the physical layout, you could possibly use multiple contactless current sensors on the wires? You could feed multiple of those back to an ESP or a Pi.

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Have you thought about the shelly i3 it could monitor 3 devices for each i3, no relay so may be more reliable over time. (mqtt or http)

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Thank you for your input, the smart plug vendor shared the "distaste" about commercial usage. I think I'm going with 3 x Shelly 3EM or 5 x Shelly EM for the contactless current sensors. Pricewise it would be better to use the Emporia vue 2, but it doesn't seem to play ball wit NR.

The shelly devices do seem well-made. Not cheap certainly though but possibly about right for the quality.

Looks like a commercial version of the open energy monitor - which is the name I was trying to think of when I gave the vague "contactless current sensors" :slight_smile:

Home | OpenEnergyMonitor

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If you are looking for something wired (vs Shelly's that are Wifi), you can also loog at PZEM energy monitors which have a serial link

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Open energymonitor seems interesting, it's maximum is 4 CT clamps, (Emporia has up to 16) but alas it's out of stock. PZEM seems interesting too. Thanks!

I use PZEM-004T with an open CT to monitor my electricty consumption. It connects via serial link to an Wemos D1 Mini, flashed with Tasmota, which communicates via MQTT to my Node-RED flow.

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Obviously, if going down this route in a commercial setting, you would also want to make sure that you were monitoring the ESP device as well so that you knew if the device fell off the network. Easily done with MQTT. Using Tasmota in the past, I've sometimes had problems with reliability. But not hard to write something custom. Using ESPHome, I've not had any reliability issues at all.

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What about deploying the following

IOTAWATT using CT clamps at your central panel - this can monitor each of the circuits for actual power draw - then put a smart plug at each timer - flash tasmota on each one

Have a Node Red flow to monitor the smart plugs when they "come alive" i.e. the time has been activated - monitor the current draw for each circuit from the iotawatt - whilst the current draw is > 0 (i.e. whilst the timer is active and powering the elements) then monitor that the smart plugs are alive (or vice versa)

If the current draw drops to zero (or approx) and the smart plug is still responding - then you know that the element has stopped drawing power but the timer is still active.

You can manage all of this with trigger nodes or a state machine in NR to make sure your conditions are met.


I looked into Iotawatt, but they are sold out right now... The Shelly reseller I contacted discouraged the use of the plugs, as the power goes through them and thus it adds a weak point according to him..

You are right about the network question, then Shelly EM has 1 year on board memory I believe.
In my usecase I need the data - to verify I that the cycle completed - at the end of the production cycle.

Yep i was not saying to put the power through the plugs - just put them in parallel with the load - and monitor the actual draw back at the switchboard.

So the smart plugs are only there as the "canary in the coal mine" to let you know that there is still power to the circuit (and hence the timer has not finished its run)


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ok, I see, makes sense.

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