Pen. Code, § 629.58

No order entered under this chapter shall authorize the interception of any wire or electronic communication for any period longer than is necessary to achieve the objective of the authorization, nor in any event longer than 30 days, commencing on the day of the initial interception, or 10 days after the issuance of the order, whichever comes first. Extensions of an order may be granted, but only upon application for an extension made in accordance with Section 629.50 and upon the court making findings required by Section 629.52. The period of extension shall be no longer than the authorizing judge deems necessary to achieve the purposes for which it was granted and in no event any longer than 30 days. Every order and extension thereof shall contain a provision that the authorization to intercept shall be executed as soon as practicable, shall be conducted so as to minimize the interception of communications not otherwise subject to interception under this chapter, and shall terminate upon attainment of the authorized objective, or in any event at the time expiration of the term designated in the order or any extensions. In the event the intercepted communication is in a foreign language, an interpreter of that foreign language may assist peace officers in executing the authorization provided in this chapter, provided that the interpreter has the same training as any other intercepter authorized under this chapter and provided that the interception shall be conducted so as to minimize the interception of communications not otherwise subject to interception under this chapter.