A shocking problem?!
Many marinas abroad are reported as having reverse polarity, with many continental adaptors able to plug in either way round to get the polarity right or wrong!
Most appliances are unaffected by this, but the UK mostly uses single-pole switches where the live supply (brown insulation) in the ‘off’ position doesn’t flow to the appliance, which can then be safely handled. If polarity is reversed then the appliance would remain live through the negative (blue insulation) although switched ‘off’! Read more from this RYA news item:-