Pennsylvania Code
Title 52 - PUBLIC UTILITIES
Part I - Public Utility Commission
Subpart C - Fixed Service Utilities
Chapter 57 - ELECTRIC SERVICE
Subchapter B - SERVICE AND FACILITIES
Section 57.23 - General testing conditions

(a) Location. Tests provided for in § § 57.20 and 57.21 (relating to watthour meter testing; and demand meter testing), except those made previous to installation, shall be made in the place of permanent location on the premises of the customer or at a laboratory equipped with adequate facilities for making tests.

(b) Tests of meters with accessories. Service meters connected to the line through instrument transformers, shunts or multipliers shall be tested jointly with accessories, unless the tests for ratio and phase angle of the instrument transformers and the resistance of the shunts have been determined in a laboratory before installation, or unless their operating characteristics affecting metering accuracy have been determined in service within the previous 10 years and are on the records of the public utility. Laboratory tests shall be deemed acceptable only when made by the National Bureau of Standards, a standardizing laboratory approved by the Commission, or by the laboratory of the public utility, whose standards have been checked, and are subject to further checks or tests by the Commission.

(c) Adjustment after test. Meters shall be adjusted as closely as practicable to the condition of zero error; the tolerances specified shall be interpreted as maximum variations from adjustments to the condition of zero error. In the adjustment of meters no improper advantages of prescribed tolerance limits shall be taken.

(d) Change of frequency. If a public utility changes its standard of frequency, it shall give reasonable notice to the customers it is serving and make necessary tests and readjust service meters as soon as practicable.