37 Installation and maintenance of computers, telephones, electronics components, plumbing, electrical systems, HVAC, utility systems, water heaters, water conditioners, telephones, telephone lines, cable television, internet services, computer networks, residential and commercial satellite receivers, home theaters, security systems, pools, spas, and irrigation and sprinkler systems; Electrical contracting, construction and maintenance services, namely, installation, repair and maintenance of electric power transmission and distribution lines, electric utilities, natural gas pipelines, telecommunication and cable television lines; construction and erection of electric substations, cellular telephone and microwave towers