Proofreading problem on punctuation's- It shall be unlawful to install wires or appliances for electric light, heat or power, operating at a potential in excess of seven hundred fifty volts, in or on any part of a building, with the exception of a central station, sub-station, transformer, or switching vault, or motor room; provided, however, that the Commissioner may authorize the use of radio transmitting apparatus under special conditions.
Are these correct?