35 Pa. Stat. § 2105
Any individual, partnership, association or corporation or any political subdivision engaged in or preparing to engage in the manufacture, transportation or storage of any product to be used in the defense of the United States or of this State or for the prosecution of war by the United States or the manufacture, transportation, distribution or storage of gas, oil, coal, electricity or water or any of said natural or artificial persons owning or operating, or both, any public utility whose property, except as hereinafter otherwise provided, is surrounded by a fence or wall or a fence or wall and buildings may post around such property at each gate entrance, dock or railway entrance a sign reading, "No Entry Without Permission": Provided, That the following kinds of property may be similarly posted in the manner hereinafter provided without the necessity of fencing:
Whoever, without permission of such individual, partnership, association, corporation or political subdivision or its or their representative, shall wilfully enter upon premises so posted or shall wilfully destroy, deface or remove any such sign shall, during a period of national emergency or war, on conviction thereof in a summary proceeding, be sentenced to pay a fine not exceeding fifty dollars ($50.00), or to undergo imprisonment not exceeding ten (10) days, or both.
35 P.S. § 2105