S-S-05—Performance Requirements Applicable to Meters Granted a Conditionally Lengthened Initial Reverification Period under S-EG-01
Category: Statistical methods
Specification: S-S-05 (rev. 1)
Issue Date: 2011-03-11
Effective Date: 2011-03-11
Table of Contents
- 1.0 Scope
- 2.0 Authority
- 3.0 Normative References
- 4.0 Lot Formation
- 5.0 Lot Formation Reporting
- 6.0 Interim Sampling
- 7.0 Use of Historic Compliance Sampling Results
- 8.0 Results and Conclusions
- 9.0 Revision
- Annex A – Interim Sampling Requirements – Modifications to ISO 2859-2:1985
This specification applies to electricity and natural gas meters granted conditionally lengthened initial verification periods under S-EG-01. This specification establishes requirements for achieving an unconditionally lengthened initial reverification period (as per section 5.4 of Bulletins E-26 and G-18). Requirements are included for achieving an unconditionally lengthened initial reverification period on the basis of results obtained from either interim sampling or historic compliance sampling results.
This specification is issued under the authority of section 19 of the Electricity and Gas Inspection Regulations.
3.0 Normative References
3.1 ISO 2859-2:1985, Sampling procedures for inspection by attributes – Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection.
3.2 S-S-01 – Specifications for Random Sampling and Randomization
3.3 S-S-02 – Measurement Uncertainty and Meter Conformity Evaluation Specifications.
3.4 S-EG-01 – Electricity and Gas Meter Pattern Approval Applications - Quality and Measurement Reliability Information Requirements in Support of a Lengthened Initial Reverification Period.
3.5 E-26 – Reverification Periods for Electricity Meters and Metering Installations
3.6 G-18 – Reverification Periods for Gas Meters, Ancillary Devices and Metering Installations
3.7 Relevant Measurement Canada specification for the verification and reverification of the meter under test.
4.0 Lot Formation
4.1 A lot presented for interim sampling inspection shall consist of meters of the same make(s) and model(s), and with the same metrological parameters as are described in an applicant's attestation letter, submitted to Measurement Canada in accordance with the requirements of reference 3.4.
4.2 To be considered eligible for the purposes of interim sampling, meters shall be manufactured under uniform conditions and shall have been placed into service within the time frame specified in section.
4.3 Pattern approval representatives applying for a lengthened initial verification period are responsible for fulfilling the following obligations within the same calendar year as that which appears on an applicant's request under the provisions of S-EG-01.
- Applicants shall demonstrate that a minimum total of 501 units of the meters referred to in section 4.1 have been produced by the meter manufacturer, and;
- Applicants shall ensure that a minimum of 200 of the subject meters have been installed in Canada (for trade purposes) within a specific calendar year and are capable of being made available for the purposes of interim sampling inspection or have been tested under the requirements of a compliance sampling plan authorized by Measurement Canada.
5.0 Lot Formation Reporting
5.1 At the time of application, applicants requesting a lengthened initial reverification period under S-EG-01 shall include within their written submission to Measurement Canada the following meter related information:
5.1.1 A copy of the applicant's attestation letter identifying the meter makes, models and configurations upon which lot formation will be based.
5.1.2 Supporting meter production and sales documentation necessary to demonstrate compliance with the requirements of section 4.3 (a) & (b).
5.1.3 A complete listing (in electronic format) of the meters falling within the scope of the applicant's attestation and which meet the requirements of section 4.3 (b).
5.2 Meter lists submitted to Measurement Canada as per section 5.1.3 shall include, as a minimum:
5.2.1 For the purposes of conducting interim sampling inspection:
- the meter make and model;
- the meter configuration (where applicable);
- the energy, demand or volume units (as applicable);
- the firmware version (where applicable);
- the serial number; and,
- the name and address of the meter owner.
5.2.2 For the purposes of demonstrating compliance on the basis of the extension levels achieved from historical sampling results, for each attestation meter grouping:
- the makes and models of meters for which compliance sampling results exist;
- the number of groups tested;
- the total number of sample meters tested;
- the identifier number of each lot sampled;
- for all lots sampled, the names and addresses of the meter owner;
- for all lots sampled, the seal extension granted;
- any further information with regard to the representativeness of the results relative to the makes and models included in the attestation lot grouping; and
- a summary conclusion with regard to the conformity assessment criteria of section 7.2.
6.0 Interim Sampling
The sampling plan parameters of ISO 2859-2 (reference 3.1), as specifically identified in this section and Annex A, shall be utilized for the purposes of interim sampling inspection.
- Meter production population (N) shall be greater than or equal to 501 units
- National sample size (n) shall equal 200 units
- Sampling Plan Limiting Qualities (LQ):
- Type 1 marginally conforming, LQ = 12.5
- Type 2 nonconforming, LQ = 3.15
6.1 Meter Performance Tests
6.1.1 For the purposes of interim sampling inspection, the meter performance tests conducted shall be the performance tests prescribed by the applicable device specification for the purposes of meter verification or reverification.
6.1.2 Performance testing shall be conducted by an accredited organization on certified measurement apparatus that, unless advised otherwise and alternate arrangements made, Measurement Canada will consider as being satisfactory to the applicant for the subject purposes.
6.1.3 Meter owners and/or applicants shall be responsible for arranging for interim sampling meter testing, conducted under the requirements of this specification, to be witnessed by Measurement Canada. Requests of this nature shall be arranged directly with the appropriate Measurement Canada office.
6.1.4 Measurement Canada reserves the right to implement inspection fees for services provided as part of interim sampling witness inspections. S-EG-01 applicants shall be responsible for all Measurement Canada fees that are associated with a request for interim testing of any meter makes or models identified in an applicant's attestation letter.
6.2 Specification Limits
For the purposes of interim sampling inspection, the applicable specification limits shall be:
- Type 1 marginally conforming: 2 %
- Type 2 nonconforming: 3 %
6.3 Conformity Test Requirements
A conforming unit for the purpose of the interim sampling plan shall be one whose performance errors are less than or equal to the specification limits of section 6.2. where conformity tests conducted (as per reference 3.7) have demonstrated, beyond any reasonable doubt (as per reference 3.3) that the values of all specified performance quality characteristics comply with the applicable requirements.
6.4 Sample Meter Disposition
Sample meters which meet meter verification requirements (reference 3.7) may be returned to service. Nonconforming meters should be appropriately dealt with.
7.0 Use of Historic Compliance Sampling Results
7.1 Where an applicant wishes to utilize historic compliance sampling results in support of obtaining an unconditionally lengthened initial reverification period, the applicant shall ensure that:
- compliance sampling results have been obtained under one of MC's authorized sampling programs;
- compliance sampling results are available for a minimum total of 200 sample meters derived from at least three (3) lots of meters representing the specific makes and models attested to under an applicant's S-EG-01 submission;
- subject to subsection (d), all results are included under the lot formation reporting requirements of section 5.0; and
- historic compliance sampling results are limited to a maximum of 10 years.
7.2 Conformity Assessment
Compliance sampling results, submitted under section 5.0 for a particular attestation population, shall be capable of demonstrating at 90% confidence that 95% of the total number of lots which have been historically assessed for meter quality under a compliance sampling program, received an extension to their initial reverification period which, when summed as a total period (in years) equates to or exceeds the conditionally lengthened period which is recognized under E-26 or G-18.
7.3 Assessment Criteria
The conformity assessment criteria referred to in section 7.2 is, in practice, an AQL of 2.0%. This criteria is considered as having been met if all lots are found acceptable, and:
- no more than 1 nonconformance is found in the combined sample of n ≥ 200 and TTT ≥ 48 months; or
- no more than 2 nonconformances are found in the combined sample of n ≥ 200 and TTT ≥ 64 months; or
- no more than 3 nonconformances are found in the combined sample of n ≥ 200 and TTT ≥80 months.
8.0 Results and Conclusions
8.1 The makes and models of meters identified in an applicant's attestation letter shall be considered as complying with the requirements for achieving an unconditionally lengthened initial reverification period, where:
- the reporting requirements of section 5.0 have been met; and
- the interim sampling performance and lot quality levels, as concerns the national meter population, are demonstrated as having been met; or
- the compliance sampling performance quality criteria under section 7.0 is demonstrated as having been met.
8.2 All meter makes and models, as identified in an applicant's attestation letter submitted in accordance with S-EG-01, shall be considered due for reverification as per the requirements applicable to meters not qualifying for a lengthened initial reverification period (refer to reference 3.5 or 3.6, as applicable) where:
- the lot formation reporting requirements of sections 5.0 have not been complied with, or
- where the performance results and quality levels of the interim sampling testing do not meet the requirements of this specification.
8.3 Where it has been established that meters, identified in an applicant's attestation letter, are due for reverification, as per the requirements applicable to meters not qualifying for a lengthened initial reverification period, the applicant shall be responsible for advising meter owners of this outcome.
8.4 Where it has been established that the initial reverification periods, for meters identified in an applicant's attestation letter, are no longer conditionally lengthened, Measurement Canada shall communicate this outcome through an update to the applicable Bulletin.
The purpose of revision 1 is to:
- Include assessment criteria in section 7.3 to support of the use of historic compliance sampling results.
Annex A – Interim Sampling Requirements – Modifications to ISO 2859-2:1985
This annex lists the modifications or amendments to ISO 2859-2:1985 for the purposes of interim sampling. All remaining requirements apply as written in the standard.
A.1 Scope and Field of Application
Procedure A (for isolated lot inspection) shall be used.
- Nonconforming Unit:
A device is a nonconforming unit if any performance specification is not met as defined in specifications issued pursuant to section 18 of the Electricity and Gas Inspection Regulations and the specification limits prescribed under section 46 of the Electricity and Gas Inspection Regulations, as applicable. Nonconforming units are also counted as marginally conforming units for the purpose of lot sentencing under section A.3.
- Marginally Conforming Unit:
A device which has no nonconformity but exhibits performance falling outside the interval defined by the lower and upper performance specification limit values (type 1 marginally conforming, see section 6.2 ).
- Measurement Device:
A device, or measurement device is an item and considered a meter.
- Responsible Authority:
For the purposes of the standard, Measurement Canada.
A.3 Rules for Acceptance and Non-acceptance
For the purposes of 4.2 of the standard, the decision regarding lot acceptance shall be based on the numbers of marginally conforming and nonconforming units in the national sample.
A device is a marginally nonconforming unit if any verification or reverification performance requirement is not fulfilled in accordance with the specification limit prescribed by section 6.2 (a).
A device is a nonconforming unit if any performance verification or reverification requirement is not fulfilled in accordance with the specification limit prescribed by section 6.2 (b) of this document.
Table A.1 prescribes the sampling acceptance criteria for marginally conforming units and nonconforming units.
A.4 Identification of Meters selected for Interim Sampling
A.4.1 Applicants who have submitted a lot formation report, as per the requirements of section 5.0, are responsible for notifying Measurement Canada of the need to initiate interim sampling. Notification shall be received by Measurement Canada no later than the end of the first week of January of the calendar year referred to in A.4.9. Notification shall include the original lot formation report and, where applicable, any updates to reflect the inclusion of meters that were installed in Canada (for trade purposes) after the date of application, yet still within the subject calendar year referred to in section 4.3 (b). Any qualifying meters excluded from the population lists must be identified and attested to (as per A.6(b)) with regard to the reason for their exclusion.
A.4.2 The sample shall be drawn at random by the responsible authority without replacement from the lot, using authorized random sampling software developed in accordance with S-S-01 (reference 3.2). The complete list of sample units shall be identified prior to commencement of any meter testing.
A.4.3 Where a national sample is drawn for the purposes of interim sampling, the owners of the sample meters selected and the approval applicant shall be notified in writing by Measurement Canada and advised of the need for removal and testing of the subject meters in accordance with the requirements of this document. Notification of meter removal and testing shall occur within 30 days of Measurement Canada receiving notice under A.4.1
A.4.4 The number of sample meters selected from a particular meter owner (contractor) for the purposes of interim sampling shall be increased by a factor of 25% to account for potential meter exclusions under sections A.4.6 and A.4.7.
A.4.5 Prior to meter removal, meter owners shall be responsible for assuring that the meters which have been identified for inclusion in the national sample meet the following criteria:
- at the time of receipt of notification, the meter is one which is currently installed in service;
- the meter's metrological parameters have not been adjusted post installation; and
- the meter has been installed for the greater of 48 months in service or the seal period applicable to meters not qualifying for a lengthened initial reverification period minus 2 years.
A.4.6 Where a meter, selected for interim sampling purposes, does not qualify for inclusion as per the requirements of A.4.5, meter owners shall not include this meter as part of the sample group required to be removed from service and shall replace it with the sequentially subsequent meter on the meter listing which meets the applicable criteria. This outcome shall be reported as per the requirements of A.6 (b).
A.4.7 Where a meter, which has been removed from service, is not capable of having its performance assessed in accordance with the requirements of this document, the meter owner shall select and remove from service an alternate meter in accordance with sections A.4.5 and A.4.6. All meters and associated test results shall be included unless compelling evidence for exclusion is identified and reported as per the requirements of A.6 (b).
A.4.8 Where a meter owner is unable to provide test results for the minimum number of meters which have been identified for the purposes of interim sample testing, the meter owner shall notify Measurement Canada and submit a report as per A.6 (b).
A.4.9 Interim sampling shall be concluded by June 30th of the year which precedes the expiration of the meter seal as per the initial reverification period prescribed as being applicable to meters not qualifying for a lengthened initial reverification period. (Refer to normative reference 3.5 or 3.6, as applicable).
A.5 Meter Inspection and Quality Characteristics
A.5.1 Each sample meter shall be examined for conformance to all pertinent acceptance requirements as referenced in sections 3.7 and 6.0.
A.5.2 Each sample meter shall be prepared for test and inspected in accordance with procedures which have been authorized by the responsible authority.
A.5.3 In accordance with the requirements of section A.4.2., sample meters owned by a particular contractor shall be inspected under identical conditions, within as short a time period as is practicable to achieve valid A.5.3.
In accordance with the requirements of section A.4.2., sample meters owned by a particular contractor shall be inspected under identical conditions, within as short a time period as is practicable to achieve valid inspection results. All sample meters relative to a particular attestation grouping, shall be assembled and available for testing on a per meter owner basis or where testing is centralized on a test site basis, prior to initiating meter performance testing.
A.5.4 The performance testing of all sample meters selected for the purposes of interim sampling shall be witnessed by Measurement Canada.
A.5.5 Meter owners and/or applicants shall be responsible for contacting the local Measurement Canada district or regional representative in order to plan the work associated with fulfilling the requirements of section A.5.4.
A.5.6 The identification of each sample meter and the test results for each performance quality characteristic examined, shall be documented as a group.
A.5.7 All sample meters shall be held in storage until completion of the national interim sampling initiative as concerns the subject meter type(s). Sample meters shall not be required to be held in storage (without just cause) after July 30th of the calendar year in which interim sampling was conducted.
A.6 Submission for Acceptance Determination
A submission for determination of lot acceptance shall include all of the following information:
- in electronic spread sheet format, the identification and test results for each meter in the sample, including the seal year;
- a documented account for each sample meter which was not withdrawn from service, not available for testing, or not tested (as per A.4.1, A.4.6 or A.4.8). This account shall include the reasons for the exclusion or unavailability, the results of the investigation into the cause of the defect, and any corrective or preventive action taken, as the case may be.
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