Some audio equipment can be affected if phase/line and neutral are correctly connected to the wall outlet.

For many, this is a form of premium, but there are those who want to know.

This only works with grounded wall sockets and if you have wall sockets suitable Schuko plugs! 

All equipment works even if the phase/line and neutral are ”inverted”, but in particular some audio devices can show a difference in performance. Therefore, it can be good to know if you have the right connection. You can always test by reversing the plug in the wall socket and listen if you notice a difference.

But as said, you can also test which contact is neutral and which is phase/line.

This device is very easy and safe to handle. Handling is very intuitive without instructions.
But it comes with a simple document, to provide security.


Plug the tester into the wall socket.
If the lamp lights up red, it means that the phase is in the connector where the red dot is.
If you turn the tester over, the red light should not light up.

This device draws only 3 mA of current. If an earth-fault circuit breaker is installed, it must still work without tripping the earth-fault circuit breaker. If the breaker should still trip, then there is something else wrong or the earth fault breaker is incorrectly set. An earth fault circuit breaker must trip from 100 – 300 mA.

Brand: NETZO

Made by Lukase AB, Sweden