-210(2) by any default of the insured other than actual fraud, the insurer did not incur any liability under the policy. § 3454. Policy as receipt An acknowledgment in a policy of the receipt of premium is conclusive evidence of its payment, as far as to make the policy binding, notwithstanding any stipulation therein that it shall not be binding until the premium is actually paid. § 3455. Overinsurance by several insurers In case of an overinsurance by several insurers, the insured is entitled to a ratable return of the premium, proportioned to the amount by which the aggregate sum insured in all the policies exceeds the insurable value of the subject at risk. § 3456. Overinsurance by simultaneous policies Wlien an overinsurance is effected by simultaneous policies, the insurers shall contribute to the premium to be returned in proportion to the amount insured by their respective policies. § 3457. Overinsurance by successive policies When an overinsurance is effected by successive policies, those only shall contribute to a return of the premium who are exonerated by prior insurance from the liability assumed by them, and in proportion as the sum for which the premium was paid exceeds the amount for which, on account of prior insurance, they could be made liable. Subchapter VIII—Loss Article A—Transfer of Interest After Loss § 3481. Agreement not to transfer An agreement not to transfer the claim of the insured against the insurer after a loss has happened, is void if made before the loss. Article B—Causes of Loss § 3491. Proximate and remote causes An insurer is liable for a loss of which a peril insured against was the proximate cause, although a peril not contemplated by the contract may have been a remote cause of the loss; but he is not liable for a loss of which the peril insured against was only a remote cause. § 3492. Rescue from peril insured against An insurer is liable where: (1) the thing is rescued from a peril insured against, and which would otherwise have caused a loss, if, in the course of the rescue, the thing is exposed to a peril not insured against, and which permanently deprives the insured of its possession, in whole or in part; or (2) a loss is caused by efforts to rescue the thing insured from a peril insured against. § 3493. Specially excepted perils If a peril is specially excepted in a contract of insurance and there is a loss which would not have occurred but for the peril, the loss is thereby excepted even though the immediate cause of the loss was a peril which was not excepted. § 3494. Willful act of insured; negligence An insurer is not liable for a loss caused by the willful act of the insured; but he is not exonerated by the negligence of the insured, or of the insured's agents or others.