Article 21

     Every lifting appliance, every item of loose gear and every sling
or lifting device forming an integral part of a load shall be -
     (a) of good design and construction, of adequate strength for the
purpose  for  which it is used,  maintained in good repair and working
order and, in the case of a lifting appliance in respect of which this
is necessary, properly installed;
     (b) used in a safe and proper manner and,  in  particular,  shall
not  be  loaded  beyond  its  safe  working load or loads,  except for
testing purposes as specified and under the direction of  a  competent
person.