PUC § 8

Writing includes any form of recorded message capable of comprehension by ordinary visual means. Whenever any notice, report, statement, petition, or record is required or authorized by this code, it shall be made in writing in the English language unless it is expressly provided otherwise.

Wherever any notice or other communication is required by this code to be mailed by registered mail by or to any person or corporation, the mailing of such notice or other communication by certified mail shall be deemed to be a sufficient compliance with the requirements of law.