Cal. Ins. Code § 1375

Where the subscribers are grouped by industries or otherwise under any ruling or agreement which exempts the funds of one group from liability in whole or in part for the payment of losses or expenses chargeable against another group, each such independent group shall maintain the reserves and surplus required for a separate exchange and the requirements of subdivisions (f) and (g) of section 1322 relative to the number and amount of risks to be assumed must be observed as to each group.