CA Prob Code Section 17452

(a)

If the petition requests that a resident of this state be appointed trustee, the petition shall be filed in the court of the county where the proposed principal place of administration of the trust pursuant to Section 17002 is located.

(b)

If the petition requests that only a nonresident of this state be appointed trustee, the petition shall be filed in the court of the county where either (1) any beneficiary resides or (2) a substantial portion of the trust property to be transferred is located or will be located.