It is the law that you must maintain all electrical equipment in efficient working order and in   good repair.

  Health & Safety at Work etc. Act 1974 (Sections 2,3 & 4)
  Puts a duty of care upon both employer & employee to ensure the   safety of all persons using the work premises.

  The Management of Health & Safety at Work Regulations 1992   state:
  Regulation 3. Risk Assessment.
(1) Every employer shall make a suitable & sufficient assessment     of
(a) the risks to the health & safety of his employees to which they     are exposed whilst at work: and
(b) the risks to the health and safety of persons not in his     employment arising out of or in connection with the conduct by     him or his undertaking.


  The Provision and Use of Work Regulations 1998

  Regulation 4. Suitability of work equipment
(1) Every employer shall ensure that work equipment is so     constructed or adapted as to be suitable for the purpose it is     used or provided.

  Regulation 5. Maintenance

(1) Every employer shall ensure that work equipment is maintained in efficient state, in efficient working order     and good repair.
(2) Every employer shall ensure that where any machinery has a maintenance log, the log is kept up to date.


  The Electricity at Work Regulations 1989

  Regulation 4. Maintenance
As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable such danger. The system means all electrical equipment.


  Failure to comply with the law could result in criminal prosecution, heavy fines & or Jail   sentence.

  Even your insurance company will insist on the fixed electrical installation being inspected &   tested on a regular basis. They will also insist on the electrical appliances being periodically   inspected & tested.