Whenever any appraisal is to be made under the standard provisions of a policy for loss or damage to property, each appraiser and umpire shall, before acting as such, take an oath that he is not directly or indirectly in the employment of the insured, the insurer, or any other insurer, that he is not related to the insured or any officer of the insurer, and that he will faithfully discharge the duties imposed upon him.