Section 460.410  Sample Testing Procedures

a)         An MSP that chooses to use sample testing shall use the procedures prescribed in any of the following documents (alone or in combination) to sample test non-demand, self-contained single-phase or three-wire network meters.

1)         ANSI/ASQC Z1.4-1993 "Sampling Procedures and Tables for Inspection by Attributes", approved 1993, American Society for Quality Control, 611 East Wisconsin Avenue, Milwaukee WI  53202. No later amendment or editions are incorporated.

2)         ANSI/ASQC Z1.9-1993 "Sampling Procedures and Tables for Inspection by Variables for Percent Nonconforming", approved 1993, American Society for Quality Control, 611 East Wisconsin Avenue, Milwaukee WI  53202. No later amendment or editions are incorporated.

b)         The MSP shall divide the meter population into homogeneous groups consisting of meters of the same basic type and purpose.  All meters within each homogeneous group shall be eligible for sampling each time a sample is taken.  A sample shall be taken each year from each homogeneous group, and testing shall be completed during the same calendar year. The size of each sample shall be determined through use of an allowed sampling procedure listed in subsection (a).

c)         The performance of a homogeneous group shall be considered acceptable when, after applying the performance criteria described in subsection (f) to each meter included in the sample, the sample indicates an acceptable quality level (AQL) at least as stringent as 2.5%. AQL shall indicate the maximum percentage of nonconforming meters to be permitted within a homogeneous group. 

d)         Each MSP shall perform 100% testing on all used or remanufactured meters purchased.

e)         Each MSP using sample testing shall file a yearly report no later than March 31 of the following year with the Chief Clerk of the Commission and provide a copy to the Manager of the Energy Division or its successor detailing the sample plan used in the previous year, along with the results of the testing program

f)         The performance of a meter that is tested as part of a sample shall be considered acceptable when its average percent registration, prior to any adjustment, is not less than 98% or more than 102%. The average percent registration for each meter shall be calculated as described in Section 460.370(d).

g)         All tests described in Section 460.370(a) shall be performed on all meters included in the sample, and all meters included in the sample shall be left adjusted so that the error shall not exceed the limits listed in Section 460.370(b).

h)         When an MSP finds the performance of any homogeneous group to be unacceptable through sample testing, the MSP shall perform corrective action on the group. Corrective actions outlined in this subsection shall be completed by the end of the second calendar year after the year in which the homogeneous group performance is initially found to be unacceptable. The corrective action shall consist of one of the following:

1)         Removal of a subgroup of problem meters from service so that the performance of the remaining meters in the group is found to be acceptable through subsequent sample testing; or

2)         Removal from service of all meters associated with the group.

(Source:  Amended at 28 Ill. Reg. 10623, effective August 1, 2004)