Political signs may not be placed on any private property (residential, commercial, or industrial) without the permission of the owner. State Penal Code Sections 556.1 and 593 govern this activity.
Penal Code Section 556.1 "It is a misdemeanor for any person to place or maintain or cause to be placed or maintained upon any property in which he has no estate or right of possession any sign, picture, transparency, advertisement, or mechanical device which is used for the purpose of advertising, or which advertises or brings to notice any person, article of merchandise, business or profession, or anything that is to be or has been sold, bartered, or given away, without the consent of the owner, lessee, or person in lawful possession of such property before such sign, picture, transparency, advertisement, or mechanical device is placed upon the property."
Signs on Utility Poles
PG&E prohibits the attachment of campaign signs to PG&E utility poles or other facilities. The U. S. Supreme court ruled that third parties have no right to use utility property to communicate messages to the public [pacific Gas and Electric v. Public Utilities Commission, 475 U.E.1 (1986)]