Pub. Util. Code, § 1710

No documents or records of a public utility or person or corporation which purport to be statements of fact shall be admitted into evidence or shall serve as any basis for the testimony of any witness, unless the documents or records have been certified under penalty of perjury by the person preparing or in charge of preparing them as being true and correct. If the person preparing them is dead or has been declared incompetent, any other person having knowledge of such statements of fact may certify the records. If certification pursuant to this section is not possible for any reason, the documents or records shall not be admitted into evidence unless admissible under the Evidence Code.

This section shall not apply to any documents not prepared, directly or indirectly, by, or under the supervision or direction of, the public utility or person or corporation offering the documents into evidence.