Every corporation organized under the provisions of Chapter 1 of Title 8, in laying any pipes or conduits in any of the public roads, highways, streets, avenues and alleys to be used for conveying steam, heat or power shall lay the same at a distance not less than 3 feet, if possible, from the outside of any water or gas pipe already laid, except in cases where it is necessary that the pipes or conduits cross any such water or gas pipe, and there such pipes or conduits shall be at least 12 inches distant from the outside of any water or gas pipe already laid.