Although the photo below is upsidedown it illustrates the problem.
Recently seen on a boat.

The male fitting shown is on the inboard (boat) end of a shore cable connected to a marina 230 volt supply. The conductors are therefore live and consequently lethal. The appalling thing is that the non-technical owner didn't even realise the danger! It was not the installation provided by the builder but was allegedly installed by a certified electrician.

+x

 

Sandy.Garrity - 12/13/2019

I've always been taught that you plug and unplug from the shore end thus never have a live cable in your hand. 

Hi Sandy,
That sounds sensible: perhaps better is to flip the circuit breakers on the electrical pedestal (if accessible) before any  disconnect either from shore or boat. Good practice indicates having all shore power needs on the boat turned off prior to unplugging, but in real life, things can be left on. Flipping the circuit breaker precludes many dangers, not least of which is a power arc when unplugging a wire still delivering power.
My best, Dick Stevenson, s/v Alchemy