A Guide to RCD's (residual current device)

In these strange times, we are all spending a lot more time at home and if we are lucky enough, in the garden.  But how can we make sure the places we want to relax in are as safe as possible?
The past few years have seen around 8,500 admissions to hospital for gardening or DIY related accidents a year.  Lawnmowers and electric tools are at the top of the offenders list.
Electric mowers and other power tools should always be used with an RCD which will cut off the power quickly in the event of an accident.