Shelly 3EM short circuit due to wrong relais wiring

I had my Shelly 3EM installed by a professional electrician today. Worked fine. All 3 phases gave the correct output. The 3EM was just connecte to 3 phases to a simple plug where my washmashine und tumbler are connected. They were both off. I then added the 3EM to my Homey. Then I tapped on the icon, when I hear a “bam” and the 3EM exploded/burst into two pieces. What is the “press” on the “3EM” Icon activating? What is the function when pressing the 3EM Icon? (For lights, it will turn on/off, but for a energy meter?)

Oh wow, wondering how the electrician hooked up your Shelly 3EM. The button in the Homey app is linked to the relay of the Shelly 3EM.

Ah. The relais. So that must have been connected wrong somehow as else the power management was showing perfect numbers on all phases. I simply don’t know what the relais is and what it switches.

If you can take a photo how it was connected, we can identify the problem. But most probable scenario is, that profesional electrician wasnt profosional enough :wink:

I will take a photo as soon as the electrician is here. What I still don’t get is what the relais is for and what function it is providing. I know the Shelly 1PM etc. and there I understand the relais. But with the 3EM I don’t even see the relais function in the schema and I didn’t see anything to “switch” in the Shelly App.

This is on the Shelly website.

It’s those I/O ports. As @Phuturist points out, they are for contactor control (a contactor is a device, typically placed inside your consumer unit, to switch a large load; basically, it’s a switch with a “remote control”, where the remote control is the 3EM). More info on Wikipedia.

I - Line input for contactor control
O - Output for contactor control

Basically when I don’t want/need to switch/control/relais anything but simply use it as energy meter, I don’t connect those “contactors” ? (I will of course verify with my electrician, I am just asking out of curiousity, and hereby thank you guys for all your answers without bashing)

BTW the original document has a different schema, I asume both are correct.


Which brings us back to the question if anything was connected by your electrician to the contacters or the Shelly 3EM was just a faulty unit where switching without anything connected short-circuited the device.

The Electrician miss-interpreted the I/O as power “input source” for the 3EM instead of an output. He feels very guilty. Thank you all for your help!

I - Line input for contactor control - it’s NOT to power the 3EM!
O - Output for contactor control - it’s NOT to power the 3EM!

On the electricians defence I have to say that the “wiring diagram” of the manual is quite confusing. That drawing is far from professional way of presenting how the device is connected and what are the devices internal connections.

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Yes it is. In the German Forum you always get bashed that you cannot read the “schema”. It’s not about the schema beeing correct it’s about how to present it to prevent confusing and ease installation. The latter ones are not good with the 3EM.

Im not professional electrician, but I was able to install this device without any issue. For IO connectors, its more then clear how to connect external device/contactor.

He’s just being right.

Being right is a wonderful thing. It’s a lot better that to help or trying to understand, why somebody misinterpreted schematics. I congratulate you for being right. I thought the forum is to HELP but looks like it’s again full of people that are righteous and proud of it.

Get better help when topic title is correct! More peeps with the same issues can find it better.

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52 but that’s no secret. Spelling my name correct you could have found out that.
About being helpfull,
As you already found out what was wrong and how to solve you could think about updating the opening post and add the correct wiring schema and a warning not to mis interpret the I and O for input power source but that it switches a galvanic isolated contact (is that correct?)

Imho better than keeping an topic that implies Homey blew up the device. There are al lot less helpfull topics that imply issues with Homey that are not issues at all but incorrect usage or missing knowledge.

I will leave it up to another moderator to reply to your flag for inappropriate reply.

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You are right (as you wish to be) and I change the topic. I used homey with a shelly 3EM while my electrician did a misinterpretation of the schematics. I was looking for information how that happend and came to the forum. Phuturist helped, I understand the problem and was wondering why this got misinterpreted.

In the shelly app I would never switch the relay but in the Homey App, the Shelly 3EM button looked greyed-out so implied to “press it” while the Shelly EM button had a solid fill. So I pushed the button.

You can easily do that in Shelly app as well. Just click on meter and button will be top right…