§ 57.20. Watthour meter testing.
(a) No watthour meter which has an incorrect register constant, test constant, gear ratio or dial train, or which ‘‘creeps,’’ that is, registers upon no load, may be placed in service or allowed to remain in service without adjustment and correction. A meter in service creeps if, with the load wires disconnected, the moving element makes one complete rotation in 5 minutes or less.
(b) For the purpose of this section, the term ‘‘light load’’ means not less than 10%, nor more than 15%, of the rated test current of the meter. The term ‘‘heavy load’’ means not less than 75%, nor more than 100%, of the rated test current of the meter.
(c) No watthour meter which has an error in registration of more than 2.0% at light load or heavy load may be placed in service or allowed to remain in service without adjustment. If, upon installation, periodic or other tests, a watthour meter is found to exceed these limits, it shall be adjusted or removed from service.
(d) A public utility shall maintain records of service watthour meters. The record for a meter shall identify the manufacturer, type, rating, year of purchase, year and location of the present installation in service, the year of the last test and the reason for the test, the registration accuracy recorded as found before adjustment and the registration accuracy recorded as left upon the completion of the test.
(e) A public utility shall make periodic tests of its watthour meters in service as follows:
(1) Two and three-wire single-phase and network-induction-type meters, up to and including 50 amperes rated test current, shall be tested at least once in each of the following periods:
(i) If manufactured prior to January 1, 1940, and the meters are not Class I and II temperature compensated and are not equipped with surge-proofed magnets or surge shields—3 years.
(ii) If the meters are Class I and II temperature compensated and are equipped with surge-proofed magnets or surge shields—15 years.
(iii) If manufactured since January 1, 1959, and the meters are Class I and II temperature compensated and are equipped with surge-proofed magnets, surge discharge gaps and a shielded magnetic bearing system—20 years.
(2) An an alternative, meters described in paragraph (1)(ii) and (iii) shall be tested according to statistical procedure in Section 8.1.8.6 of the current edition of the ANSI C-12 Code for Electric Meters, Fifth Edition.
(i) Groups which meet the accuracy requirements of the applied statistical procedure shall continue in service without test or adjustment until a subsequent annual statistical analysis indicates the need for corrective action or the Commission on its own motion requests retest of either entire groups or individual meters. Test results affecting billing shall be furnished to customers without charge.
(ii) Groups which fail to meet the accuracy requirements of the applied statistical procedure are subject to one of the following immediate corrective measures:
(A) Meters within the group affected shall be removed from service upon notification to the Commission and in compliance with a program acceptable to the Commission. A customer’s accounts billed according to registration by these meters shall be retained by the public utility from 2 years prior to discovery of registration error until date of meter removal or adjustment. Test results affecting billing shall be furnished to customers without charge and shall be retained by the public utility for at least 2 years after the meter is retired.
(B) Meters within groups affected shall be placed on an accelerated program of testing and maintenance until subsequent annual statistical analysis indicates that the affected groups again meet the accuracy requirements of the statistical testing program. Records of customer accounts and of test results affecting billing shall be retained by the public utility and furnished to customers under clause (A).
(3) Two and three-wire single-phase and network-induction-type meters, of over 50 amperes rated test current, shall be tested at least once every 8 years.
(4) Single-phase meters connected through current transformers or current and voltage transformers shall be tested as follows:
(i) Meters without surge-proof magnets, at least once every 8 years.
(ii) Meters with surge-proof magnets, at least once every 16 years.
(5) Self-contained polyphase meters shall be tested as follows:
(i) Meters without surge-proof magnets, at least once every 8 years.
(ii) Meters with surge-proof magnets, at least once every 16 years or according to statistical procedures as described in paragraph (2).
(6) Polyphase meters connected through current transformers or current and voltage transformers shall be tested as follows:
(i) Meter without surge-proof magnets, at least once every 8 years.
(ii) Meters with surge-proof magnets, at least once every 16 years.
(f) An alternating current watthour meter shall be tested and adjusted before installation for correct registration within ±2%, at a power factor of approximately 50% and 100% at rated test current. When in service, meters not tested and adjusted before installation shall be tested and adjusted to the percent accuracy specified as soon as the circumstances permit, or shall be removed from service.
(g) A service watthour meter installed shall be tested for accuracy by the public utility prior to its installation, or shall be so tested within 90 days after its installation. It shall also be inspected by the public utility for proper connection, mechanical condition and suitability of location within 90 days after installation.
(h) A service watthour meter which is removed from service shall be tested for ‘‘as found’’ registration accuracy.
Authority The provisions of this § 57.20 amended under the Public Utility Code, 66 Pa.C.S. § § 501, 1501 and 1504.
Source The provisions of this § 57.20 adopted February 25, 1946; amended through May 29, 1973; amended January 2, 1981, effective January 3, 1981, 11 Pa.B. 19; amended August 7, 1987, effective August 8, 1987, 17 Pa.B. 3324. Immediately preceding text appears at serial pages (103566) to (103567) and (80594) to (80595).
Cross References This section cited in 52 Pa. Code § 57.22 (relating to request tests and fees); 52 Pa. Code § 57.23 (relating to general testing conditions); 52 Pa. Code § 57.24 (relating to adjustment of bills for average meter error); and 52 Pa. Code § 57.254 (relating to advanced meter standards).
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