Traffic signals shall be placed at such height as to be plainly visible to approaching traffic at a distance of at least one hundred and fifty feet from the intersection, and shall, if within the curb line and operated by electricity, be placed at a height of from eight to ten feet above the pavement. If on bracket, mast arm or cable, the signal shall clear the pavement by fourteen feet and six inches.
N.J.S. § 39:4-110