Pennsylvania Statutes Title 43 P.S. Labor § 26-3. Warning sign required

The owner, agent, lessee, bailee, user, or employer responsible for the operations of equipment shall provide such warning signs on equipment or at the work site as may be required by regulations promulgated hereunder. The requirement that warning signs be posted shall not apply to railway equipment operating on railway right-of-way in relation to high-voltage conductors of such railway system under conditions for which exemption is granted under section 7.  1