Hello all thought I would jump in here as I used to be a sparky in a former life . This is from memory but im 99% positive that all portable buildings including caravans have to be wired to aus standard 3001 that states all switches have to be double pole, that is switching both positive and neutral conductors as this safe guards against reversed extension leadsLearned something the other day when I had a RCD that continually tripped.
When you switch something off at the power point, the device can still be live as you only isolate the active with the neutral wire still being live. The only way to ensure the device is not live is to unplug it. Any sparkies out there care to expand.