Electrical apparatus installation; Electrical apparatus repair; Maintenance and repair of electrical apparatus; Maintenance and repair of instruments; Maintenance, installation and repair of electrical items and equipment; Installation of electricity generators; Electric appliance installation and repair; Maintenance and repair of communications systems; Maintenance of electronic monitoring devices; Burglar alarm installation and repair; Fire alarm installation and repair; Maintenance and servicing of fire alarm systems; Replacement of batteries; Diagnosis of faults; Diagnostic maintenance services