Electrical safety/overloading

Hi all,

I have the following technical question:

The Shelly devices (not only the 4PM, but all of them), are certified up to 16A.

Yet, the specs state that the device(s) are protected:

"

• LAN, Wi-Fi, and Bluetooth connection
• 4 outputs, 16A each. Total device maximum of 40A
• Precise power metering
• Overpower and overvoltage protection of the load

"

All my wall plugs are grouped into 4 circuits, each circuit having a 20A automatic breaker.

Now my question:

It is very unlikely, but not impossible, that a certain circuit load exceeds the 16A, e.g. 18A.

The 20A circuit breaker will not trip (as the load has not been exceeded).

The Shelly 4PM should protect against 16A+ (the 18A is obviously too much)

My question is:

WHAT WILL HAPPEN if the above situation occurs (unlikely, but not impossible)?

And the same question applies to "what if the total current across all circuits exceeds the 40A limit, but not the individual 16A of each channel of the 4PM"

Zitat

Nobody will have tested this because it is outside the permitted environment. My advice, simply install appropriate 16A fuses, then you are and will stay on the safe side. Even the 4PM must not go over the 40A total. With the appropriate fuses in front of it, this can be operated without further ado.

Thx for your reply MIHO, but it doesn't really answer the question.

But iIf the device is indeed protected against overload and overpower, then someone must have tested it, otherwise it wouldn't be CE compliant/certified.

So the question still remains:

What if the device experiences overload or overpower on any or all of the lines, because they are stated as protected?

Will it trigger an internal shut-off, is there an internal fuse, will it shut down the concerned Lx line?

What if the total on the 4 lines exceeds 40A, while all 4 remain under 16 (e.g.: each circuit loading 11A, making 44A in total, which is a situation which is more likely to occur).