I feel a bit dumb about this but here goes ................ For many years we (wife and I) travelled in our Land Rover Defender but now have our first motorhome. We have never used electrical plug-in for on-site electricity and although we have one of these https://kalledaskabel.de/CEE-Verlaengerung-KALLE-Blue-SIGNAL-25mm-Winkel-25-Meter don't know something key - super-important, I believe - about plugging it in. It's necessary, isn't it, in order to protect the vehicle electrical system, to first switch something in the vehicle OFF before plugging into the mains? What are the precautions to be aware of? We expect to be using sites in Germany, the Netherlands, the UK, Scandinavia.