Good advice from all regarding waterproofing, but don't expect the locals to do the same. Found the fridge not working in the past due to someone else's connection being full of water and the site box tripped.
Don't know from your post count if you are new to caravanning, but if its your first time in France, be aware that reverse polarity is a real possibility. There are diverse opinions about this, but we carry an adaptor to deal with this possibility. Some sites don't have the usual EHU connector so a 2 pin adaptor is advisable too