Low relay has voltage

So recently i wired mega2560 with 6 relay shield , they have separate PSU and only one relay is active at a time for different time .

What is the deal, when relay is HIGH (220v powering small indicator lights ,one at time) all of LOW relays has 40v on my multimeter and test lamp ,with multimeter im measuring N on 220v power and L on normal-closed connector of relay and boom 40v...

Sorry for bad eng...

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It's hard to understand You, BUT.... Please post schematics! Pictures are international, understood all around the world..
Pen and paper often works well.

Are you saying the relay shield power is floating on mains hum? If its an isolated power supply, and the opto-isolator inputs are used in the fully isolated mode that could happen.

I'm not a fan of floating power supplies, but its not necessarily a problem if it is like this and the inputs are opto-isolated.

Sooo, i bouth new multimeter and its ok. Multimeter was problem but my mega2560 sill restarts after some time or just freezes...

How do you know?

Post pics of your serial monitor prints when the thing has frozen or rebooted.

Why put 12V into the Mega when 7 volts will be thrown away as heat?

It was problem with multimeter, but it still restarts and bugs i also tried another board, same heppens...