California Code, Public Utilities Code - PUC § 8035

None of the provisions of Sections 8026 to 8034, inclusive, apply to direct current electric wires or cables having the same polarity, nor to signal wires when no more than two (2) of such signal wires are attached to any one pole, but no such direct current or signal wires shall in any case be run, placed, erected, or maintained within the distance of thirteen (13) inches from the center line of any pole other than the pole or poles on which the wires or cables are carried, carrying electric wires or cables. As between any two wires, or cables, or any wire or cable run, placed, erected, or maintained in violation of this section, only the wire or cable last in point of time run, placed, erected, or maintained shall be held to be run, placed, erected, or maintained thus in violation of this section.