Mich. Admin. Code R. 460.3613a

Current through Vol. 24-21, December 1, 2024

Section R. 460.3613a - Electro-mechanical meter and metering equipment testing requirements

Rule 613a.

(1) The testing of any unit of metering equipment must consist of a comparison of its accuracy with a standard of known accuracy. Units that are not properly connected or that do not meet the accuracy or other requirements of these meter and metering equipment rules at the time of testing must be reconnected or rebuilt to meet these requirements and must be adjusted to within the required accuracy and as close to zero error as practicable or must be discontinued.

(2) Self-contained, electro-mechanical, combination electro-mechanical and solid state, single-phase, and network meters must comply with all of the following requirements:

(a) Be checked for accuracy as provided for in R 460.3602.

(b) Notwithstanding the provisions of subdivision (a) of this subrule, the testing of self-contained, electro-mechanical, combination electro-mechanical and solid state, single-phase, and network meters in service must be governed by a quality control plan that complies with all of the following:

(i) Meters must be divided into homogenous groups by manufacturers" types, and certain manufacturers" types must be further subdivided into separate groups by manufacturers" serial numbers.

(ii) The meters in each homogeneous group must then be further subdivided into lots of not less than 301, and not more than 35,000, meters each, except that meters of the most recent design may be combined into lots regardless of manufacturers" type, except that where the number of meters of a single type is 8,001 or more, that number of meters must be segregated by types for the formation of lots.

(iii) From each assembled lot, a sample of the size specified in table A-2, ANSI/ASQ Z1.9-2003(R2018), must be drawn annually. The sample must be drawn at random.

(iv) The meters in each sample must be tested for accuracy pursuant to paragraphs (v) to (xi) of this subdivision.

(v) The test criteria for acceptance or rejection of each lot must be based on the test at heavy load only and must be that designated for double specification limits and an acceptable quality level (AQL) that is not higher than 2.50 (normal inspection) as set forth in table B-3, ANSI/ASQ Z1.9-2003(R2018).

(vi) The necessary calculations must be made pursuant to Example B-3 of ANSI/ASQ Z1.9-2003(R2018). The upper and lower specification limits, U and L, must be 102% and 98%, respectively.

(vii) A lot must be rejected if the total estimated percent defective (p) exceeds the appropriate maximum allowable percent defective (M) as determined from table B-3 as specified in paragraph (v) of this subdivision.

(viii) All meters in a rejected lot must be tested within a maximum period of 60 months and be adjusted pursuant to the provisions of R 460.3607 or be replaced with meters that comply with the requirements of R 460.3607.

(ix) During each calendar year, new meter samples must be drawn as specified in this subdivision from all meters in service, with the exception that lots that have been rejected must be excluded from the sampling procedure until all meters included in the rejected lots have been tested.

(x) The electric utility or cooperative may elect to adopt the following sample plan for lots that have been rejected the previous year:

(A) From each rejected lot, a sample of the lot size specified in table A-2, ANSI/ASQ Z1.9-2003(R2018) using general inspection level III, must be drawn at random.

(B) The test criteria for acceptance or rejection of each lot must be based on the test at heavy load and must be that designated for double specification limits and an acceptable quality level (AQL) that is not higher than 2.50 (tightened inspection) as set forth in table B-3 of ANSI/ASQ Z1.9-2003(R2018).

(C) The necessary calculations must be made pursuant to Example B-3 of ANSI/ASQ Z1.9-2003(R2018). The upper and lower specification limits, U and L, must be 102% and 98% respectively.

(D) A lot must be rejected if the total estimated percent defective (p) exceeds the appropriate maximum allowable percent defective (M) as determined from table B-3 specified in paragraph (B) of this subdivision. If the acceptability criteria of the sampling plan are met, then the lot is considered acceptable and must be returned to the variables sampling plan the following year. If the acceptability criteria of the sampling plan are not met, then the electric utility or cooperative shall reject that lot and all meters in that lot must be tested and adjusted or replaced within a maximum period of 48 months after the second rejection.

(xi) The plan specified in paragraph (x) of this subdivision does not alter the rules under which customers may request special tests of meters.

(c) Be checked for accuracy in both of the following situations:

(i) When a meter is suspected of being inaccurate or damaged.

(ii) When the accuracy of a meter is questioned by a customer under R 460.3601.

(d) Be inspected for mechanical and electrical faults when the accuracy of the device is checked.

(e) Have the register and the internal connections checked before the meter is first placed in service and when the meter is repaired.

(f) Have the connections to the customer's circuits checked when the meter is tested on the premises or when removed for testing.

(g) A meter may not be tested or checked for any reason if the device was tested, checked, and adjusted within the previous 12 months except when a complaint is received.

(3) All single-phase transformer-rated electro-mechanical meters must comply with all of the following requirements:

(a) Be checked for accuracy at unity power factor at the point where a meter is installed, at a central testing point, or in a mobile testing laboratory when any of the following occurs:

(i) Not later than 9 months after 144 months of service for a surge-resistant meter and not later than 9 months after 96 months of service for a non-surge-resistant meter.

(ii) When a meter is suspected of being inaccurate or damaged.

(iii) When the accuracy of a meter is questioned by a customer under R 460.3601.

(iv) Before use when a meter has been inactive for more than 1 year after having been in service.

(b) Be inspected for mechanical and electrical faults when the accuracy of the device is checked.

(c) Have the register and the internal connections checked before the meter is first placed in service and when the meter is repaired.

(d) Have the connections to the customer's circuits checked when the meter is tested on the premises or when removed for testing.

(e) Be checked for accuracy at 50% power factor when purchased and after rebuilding.

(f) A meter may not be tested or checked for any reason if the device was tested, checked, and adjusted within the previous 12 months except when a complaint is received.

(4) All self-contained electro-mechanical, combination electro-mechanical meters, solid-state 3-phase meters, and associated equipment must comply with all of the following requirements:

(a) Be tested for accuracy at unity and 50% power factor when any of the following occur:

(i) Before being placed in service.

(ii) Not later than 9 months after 120 months of service.

(iii) When a meter is suspected of being inaccurate or damaged.

(iv) When the accuracy of a meter is questioned by a customer under R 460.3601.

(v) When a meter is removed and put back in service.

(b) Be inspected for mechanical and electrical faults when the accuracy is checked.

(c) Have the register and internal connections checked before the meter is first installed, when repaired, and when the register is changed.

(d) Have the connections to the customer's circuits and multipliers checked when the equipment is tested for accuracy on the customer's premises.

(5) An electric utility or cooperative may elect to include self-contained solid state 3-phase meters in service in its quality control plan as provided for in subrule (2)(b) of this rule. An electric utility or cooperative may be exempt from the periodic meter test requirements as provided in subdivision (a)(ii) of subrule (4).

(6) All transformer-rated electro-mechanical 3-phase meters, all combination electro-mechanical and solid state 3-phase meters, and associated equipment must comply with all of the following requirements. However, an electric utility or cooperative may elect to include transformer-rated solid state 3-phase meters in service in its quality control plan as set forth in subrule (2)(b) of this rule. Therefore, an electric utility or cooperative may be exempt from the periodic meter test requirements as provided in subdivision (a)(iii) of this subrule.

(a) Be checked for accuracy at unity and 50% power factor when any of the following occur:

(i) Before being placed in service.

(ii) On the customer's premises within 60 days after installation, unless the transformers comply with the specifications outlined in the American National Standards Institute standard ANSI C-57.13, and unless the meter adjustment limits do not exceed plus or minus 1.5% at 50% power factor.

(iii) Not later than 9 months after 72 months of service.

(iv) When a meter is suspected of being inaccurate or damaged.

(v) When the accuracy is questioned by a customer under R 460.3601.

(vi) When a meter is removed and put back in service.

(b) Be inspected for mechanical and electrical faults when the accuracy is checked.

(c) Have the register and internal connections checked before the meter is first placed in service and when the meter is repaired.

(d) Have the connections to the customer's circuits and multipliers checked when the equipment is tested for accuracy on the premises, when removed for testing, or when instrument transformers are changed.

(e) Be checked for accuracy at 50% power factor when purchased and after rebuilding.

Mich. Admin. Code R. 460.3613a

2023 MR 7, Eff. 4/10/2023