The commission may appoint inspectors of electric meters whose duty it shall be when required by the commission to inspect, examine, prove and ascertain the accuracy of any and all electric meters used or intended to be used for measuring and ascertaining the quantity of electric current furnished for light, heat or power by any public service company to or for the use of any person or corporation, and to inspect, examine and ascertain the accuracy of all apparatus for testing and proving the accuracy of electric meters, and when found to be or made to be correct the inspector shall stamp or mark all such meters and apparatus with some suitable device to be prescribed by the commission. No public service company shall furnish, set or put in use any electric meters the type of which shall not have been approved by the commission.