Sec. 10.
(a) A
utility may adopt either Method A as described in subsection (b) or Method B as
described in subsection (c) for maintaining the accuracy of self-contained
meters without attachments or with frictionless attachments.
(b) For Method A, periodic testing of
watthour meters, each public utility shall, after the adoption of this rule,
use not more than a sixteen (16) year schedule of periodic testing.
(c) For Method B, quality control testing of
watthour meters, a public utility may adopt the following quality control
testing method for self-contained watthour meters, in service, on written
notice to the commission:
(1) Meters shall be
divided into homogenous groups.
(2)
The meters in each group may be further subdivided into lots; however, no lot
size shall be less than three hundred one (301) meters.
(3) From each lot there shall be drawn
annually a number of meters to be tested as specified in Table A-2, ANSI/ASQC
Standard Z1.9, dated 1993, using Inspection Level II. Due care shall be
exercised that the meters to be tested shall be drawn at random, and all such
meters shall be tested for accuracy.
(4) The test criterion for acceptance or
rejection of each lot shall be based on the test at full load only and shall be
that designated for Double Specification Limit-Variability Unknown-Standard
Deviation Method at the 2.50 Acceptable Quality Level (normal inspection) as
shown in Table B-3, ANSI/ASQC Standard Z1.9, dated 1993.
(5) The necessary calculations shall be made
in accordance with the illustration (Example B-3), ANSI/ASQC Standard Z1.9,
dated 1993. The upper and lower accuracy specification limits, U and L, shall
be one hundred two percent (102%) and ninety-eight percent (98%),
respectively.
(6) A lot shall be
rejected if the total estimated percent defective (p) exceeds the appropriate
maximum allowable percent defective (m) as determined from Table B-3, ANSI/ASQC
Standard Z1.9, dated 1993.
(7)
Meters in a rejected lot shall be subject to an accelerated test schedule to be
completed within a maximum period of ninety-six (96) months and shall comply
with section 9 of this rule, or shall be retired from service. Such accelerated
testing of a rejected lot may be discontinued when the subsequent test results
show that the lot is within acceptable limits of accuracy.
(8) A public utility, operating under this
optional testing plan, may elect to test the meters included in any group or
lot on a test schedule of not more than sixteen (16) years subject to section 9
of this rule.
(9) Each public
utility shall keep all necessary records to enable the commission to check
procedures followed, tests made, and calibrations employed in conformance with
this optional testing method.
(10)
All provisions of the aforesaid ANSI/ASQC Standard Z1.9, dated 1993,
explanatory of or essential to the application of Table A-2, Table B-3, and
Example B-3, as referenced in subdivisions (3) through (5), are hereby
incorporated in this rule by reference.
(d) Requirements for other watthour meters
are as follows:
(1) Electromechanical watthour
meters with surge proof magnets and the following:
(A) Mechanical KWH registers shall be tested
at least every sixteen (16) years.
(B) Mechanical demand registers shall be
tested at least every eight (8) years.
(C) Electronic demand registers shall be
tested at least every sixteen (16) years.
(D) Mechanical cam pulse initiators shall be
tested at least every two (2) years.
(E) Mechanical gear shutter pulse initiators
shall be tested at least every eight (8) years.
(F) Electronic pulse initiators shall be
tested at least every twelve (12) years.
(G) Electronic registers, for example, TOU or
recorder, shall be tested at least every sixteen (16) years.
(H) Thermal demand registers shall be tested
at least every eight (8) years.
(2) Electronic meters shall be tested at
least every sixteen (16) years.