Surveying apparatus and instruments; cables, electric; photovoltaic cells; vacuum tubes (radio); contacts, electric; integrated circuits; variometers; time switches, automatic; wire connectors (electricity); control panels (electricity); transistors (electronic); junction boxes (electricity); remote control apparatus; coils, electric; capacitors; distribution boxes (electricity); couplings, electric; resistances, electric; relays, electric; distribution consoles (electricity); rheostats; lighting ballasts; transformers (electricity); light dimmers (regulators), electric; plugs, sockets and other contacts (electric connections); cell switches (electricity); current rectifiers; circuit breakers; electric apparatus for commutation; solar batteries; switches, electric