It is unlawful for anyone except an individual licensed by the City of Philadelphia to install electrical equipment and wiring. The owner of any property wherein any such installation is discovered shall be issued a violation by the Department of Licenses and Inspections. The limited exceptions include replacing devices and fixtures at existing outlets.
Answer in February 2010 is by Jim Miraglia of the Department of Licenses and Inspections. http://wilberelectrical.blogspot.com...ical-work.html
I had always thought homeowners were allowed, but a recent issue led me to seek an official answer. So why can these home centers sell the equipment to unlicensed people? For the same reason they sell fireworks in PA, but it is illegal to possess them [go figure that one out...]