(1) For mechanical or lagged demand meters, the error at the customer’s average billing demand over the refund period shall be used to determine the amount to refund or backbill the customer. This error shall be determined by testing the meter at both 40 percent and 80 percent of meter full scale value, as read on the standard or reference meter, or as near to these two points as is practicable. The following formula shall be used to estimate the kilowatt error of the meter at the customer’s average billing demand:
Eavg = [E80 – E40]/[M80 – M40]*[Mavg – M40] + E40
where:
Mavg denotes the customer’s average billing demand over the refund period;
M40 and M80 denote the kilowatt readings on the meter being tested when the reference meter is at 40 percent and 80 percent of the full-scale value of the meter being tested, respectively;
E40 and E80 denote the kilowatt errors on the meter being tested corresponding to M40 and M80, respectively; and
Eavg denotes the estimated kilowatt error at the customer’s average billing demand.
The kilowatt error is determined, Eavg, shall be expressed as a percentage, P, of the reference meter reading corresponding to the average billing demand. This percentage shall be used to determine the corrected billing demand for each month of the refund period. A correction factor, C.F., will be applied to the original billing demand for each month in the refund/backbill period to determine the corrected billing demand for each month as follows:
C.F. * Original Billing Demand = Corrected Billing Demand
where:
C.F. = [1/(1+P)]
and P is the percentage error of Eavg relative to the reference meter reading corresponding to the average billing demand over the refund/backbill period.
    (2) For watthour and electronic demand meters, the percentage error to be used for refunds and backbills shall be the same percentage calculated when tested for watthour registration as set forth in subsection 25-6.058(1) and Fl. Admin. Code R. 25-6.058(2)(b), respectively. A correction factor, C.F., will be applied to the original billing demand/energy for each month in the refund/backbill period to determine the corrected billing demand/energy for each month as follows:
C.F. * Original Billing Demand/Energy = Corrected Billing Demand/Energy
where:
C.F. = [1/1(1+P)]
and P is the percentage error calculated according to subsection 25-6.058(1), F.A.C., for watthour meters and Fl. Admin. Code R. 25-6.058(2)(b), for electronic demand meters.
    (3) Over-registering meters. Whenever a meter tested is found to have an error in excess of the plus tolerance allowed in Fl. Admin. Code R. 25-6.052, the utility shall refund to the customer the amount billed in error as determined by subsection (1) or subsection (2) of this rule for one half the period since the last test, said one half period shall not exceed twelve (12) months; except that if it can be shown that the error was due to some cause, the date of which can be fixed, the overcharges shall be computed back to but not beyond such date based upon available records. The refund shall not include any part of any minimum charge.
    (4) Under-registering meters.
    (a) A utility may backbill in the event that a meter is found to be under-registering. A utility may not backbill for any period greater than twelve (12) months. If it can be ascertained that the meter was under-registering for less than twelve (12) months, then the utility may backbill only for the lesser period of time. In any event, the customer may extend the payments of the backbill over the same amount of time for which the utility issued the backbill.
    (b) Nothing in paragraph (4)(a) of this rule shall be construed to limit the application of Fl. Admin. Code R. 25-6.104, or prohibit a utility from backbilling for four years pursuant to subsection (7) of this rule.
    (c) Whenever a meter is tested and not subject to Rule 25-6.104 or subsection 25-6.105(5), F.A.C., and is found to have an error in excess of the minus tolerance allowed by Fl. Admin. Code R. 25-6.052, the utility may bill the customer an amount equal to the unbilled error as determined by subsection (1) or subsection (2) of this rule. If the utility has required a deposit for a meter test as permitted under subsection (2) of Fl. Admin. Code R. 25-6.059, the customer may be billed only for that portion of the unbilled error which is in excess of the deposit retained by the utility.
    (5) In the event of a non-registering meter or a meter for which the test results are inconclusive, the utility may bill the customer on an estimate based on previous bills for similar usage or on other sources of available data provided.
    (6) Creeping. Whenever a meter, upon proper testing, is found to have a registration error due to “”creep”” in excess of the tolerance allowed by Fl. Admin. Code R. 25-6.052, the error shall be calculated by timing the rate of “”creeping”” and assuming that the creeping affected the registration of the meter for 25% of the time, unless a more accurate estimate of the percentage of time the meter should have been inactive can be obtained.
    (7) Where a utility determines that a service location has not previously been properly metered through errors of an electrical contractor, the utility may backbill for up to four years from the date of notice to the customer that the error has been discovered. The customer may extend the payments of the backbill over the same amount of time for which the utility issued the backbill.
Rulemaking Authority Florida Statutes § 366.05(1). Law Implemented 366.03, 366.041(1), 366.05(1), (3), (4), 366.06(1) FS. History-New 7-29-69, Amended 4-13-80, 5-3-82, 7-3-06.