How to separate live wire from reversible plug (eg: EU plug)

Thread Starter


Joined Aug 4, 2021
Hello, electronic noob here

You may or may not know that EU plugs can be inserted into the socket in 2 ways. This means the live and neutral can be on either wire. I want to know if there is a device or circuit that can separate the live and neutral and always output them on the same wire.

( This power meter can supposedly only function if the live wire is inserted in port 4 and the neutral in port 3, but since a EU plug can be reversed this is obviously a problem.

I've attached an images to illustrate the issue. Purple is either live or neutral. "M" is the magical device that separates live and neutral. "P" is the power meter


Joined Mar 14, 2008
Why are you using a 100A meter for measuring power from a standard mains outlet?

Assume one wire is "hot" and one is "neutral", and then connect the meter properly including the current transformer, to those arbitrarily labeled points.
Then, without a connection to earth common, the meter then won't be able to tell which way the plug is connected (and neither can you).
Adding a polarity correcting circuit is unneeded.