(e) Electric plant contributed to the utility or constructed by it from contributions to it of cash or its equivalent shall be charged to the electric plant accounts at cost (see section 180.1[a][6] of this Title) to the utility (i.e., original cost less the portion thereof contributed by or on behalf of customers). Records shall be kept so that the utility can readily furnish information as to the source, purpose, and amount of each contribution, the property to which each contribution relates, and the conditions, if any, upon which each contribution was made. Note A:Amounts received for construction which are ultimately to be refunded, wholly or in part, shall be credited to account 1241, Customer Advances for Construction. When the amount to be refunded has been finally determined, the balance, if any, remaining in account 1241 shall be debited thereto and credited to the electric plant accounts to which the cost of the property was charged.