California Code, Public Utilities Code - PUC § 8032

No person shall place, erect, or maintain on any pole, or any crossarm or other appliance on the pole, which carries or upon which is placed an electric arc lamp, any transformer for transforming electric currents.  This section shall not apply if the arc lamp is suspended so that it can be trimmed from the ground or from a stand located on the pole not less than seven feet below the transformer, and in so suspending the arc lamp no wire or cable in connection therewith is run vertically on the pole unless the wire or cable is protected as provided for in Section 8031.