Section 503: Periodic & Sample Testing

I. Objective:

To determine an acceptable testing program to provide a level of assurance of PEC’s meter accuracy.

II. Policy Content:

To establish certain intervals and sampling programs during a calendar year for the various types of PEC meters in use.

III. Provision:

A. New Meters

All new meters should be inspected and tested in PEC’s meter testing facility or by the manufacturer prior to installation. Each meter should meet the accuracy requirements of PEC Policy No. 502.
Meters installed with instrument transformers shall be tested on a one hundred percent (100%) basis and adjusted to conform to the accuracy requirement outlined in PEC Policy No. 502 prior to installation. In addition, a complete inspection shall be made of the wiring after installation to assure proper connections for metering.
The watt-hour meters may be tested independently of instrument transformers, provided the transformer ratios and phase angles have been determined and are taken into account in the calibration of the meters. The transformer errors may be neglected in the calibration of the meters if instrument transformers are used that conform to the 0.3 accuracy class limits of the ANSI requirements with the actual secondary burden.

B. Periodic schedule for testing alternating current watt-hour meters with surge proof magnets and without demand registers or pulse initiators.

The word “year” in the periodic test schedule stated below means calendar year. The periods stated are required test intervals, except for single phase meters which required sample testing based on Military Standard 414.

  1. Meters used with instrument transformers:
    1. Polyphase meters – at least once in 16 years
    2. Single phase meters – see B.2. below.
  2. Single phase meters.
    A one percent (1%) random sampling of all installed groups of single phase meters will be taken annually, with a minimum of twenty for each group. The sampling will be checked to be sure that the lot of each type is in accordance with that which is specified in Table A-2 of Military Standard 414.
    An as-found test will be performed on these meters and recorded. Bar X and Sigma method of computing the average calibration and the standard deviation for each type of meter will be made.
    These calculations will determine how this group of meters compares to the acceptable quality level (AQL). If outside the AQL, an appropriate correction on this group of meters will be made, such repair, recalibration or retirement, to be completed within an appropriate period of time.
  3. Self-contained polyphase meters and three-wire network meters – at least once in 16 years.

C. Varhour Meters

Varhour meters shall be tested in accordance with the schedule for the associated watt-hour meters.

D. Other Meters

Meters without surge-proof magnets and without demand registers or pulse initiators – at least once in 8 years.

E. Schedule for Testing Demand Meters

The following schedule is required for testing demand meters:

  1. Rolling or block interval demand registers equipped watt-hour meters – 12 years.
  2. Pulse recorders and pulse-operated demand meters in combination with pulseinitiator- equipped watt-hour meters – 2 years. If a comparison is made between the meter registration and the recorder registration each billing period, and the recorder registration agrees within one percent (1%) of that registered by the associated meter, the schedule for pulse recorders and the pulse-operated demand metering equipment should be 16 years. If recorder meter registration checks do not agree within (1%) one percent, the demand metering equipment should be tested.

IV. Responsibility

It will be the responsibility of the Manager of Transmission and Distribution Services, Field Services Unit Manager, and Director of Technical Services to properly administer these provisions.

Approved by the Board of Trustees

  • Effective Date: January 1, 1994
  • Revision Date: March 24, 2000
  • 2nd Revision Date: July 27, 2009
  • 3rd Revision Date: January 23, 2020