It's only acting as a Faraday cage if the oven is earthed so if you unplug it from the wall socket you will lose the earthing, leave it plugged in and switched off at the wall socket.

It's only acting as a Faraday cage if the oven is earthed do if you unplug it from the wall socket you will lose the earthing, leave it plugged in and switched off at the wall socket.