No sign shall be erected, constructed or maintained so as to obstruct any fire escape, or any window, door or opening used as a means of egress or for fire-fighting purposes, or so as to prevent free passage from one part of a roof to any other part thereof. No sign shall be attached in any form, shape or manner to a fire escape.

All connections of signs to frame structures shall be by steel angle plates properly secured to the building with bolts or lag screws. No sign shall be secured with wood strips or light gauge wire. All signs shall be constructed to resist a wind pressure of fifty pounds per square foot.

All wiring to freestanding signs shall be underground.