In this section, “meter” or “meters” may refer to metering system(s).

1. (1) Watthour meters used for measuring electrical quantities supplied to customers shall:

   1. (a) Be of proper design for the circuit on which they are used, be properly connected and installed, be in good mechanical condition, have adequate insulation, correct internal connections and correct register.
   2. (b) Not creep at “no load” a full revolution of the disk in 10 minutes or less when the load wires are disconnected and potential is impressed or in a test in the shop where the load wires are disconnected and the permissible voltage variation impressed. If the rate of creep can be determined in a shorter interval, it is not necessary to wait the full 10-minute period.

   3. (c) If the meters are designed for use on alternating current circuits, they shall be accurate to within plus or minus 1% at 2 load tests: one equal to between 8% and 12% of full reference test current at unity power factor and the other between 90% and 110% of full reference test current at unity power factor; and for polyphase meters, shall be accurate to within plus or minus 2% at between 75% and 100% full reference test current and approximately 50% lagging power factor. For self-contained meters the reference test current shall be the ampere or test ampere rating of the meter, whichever is shown on the nameplate. For meters used with current transformers the reference test current shall be the test-ampere rating of the meter or the secondary rating of the current transformers.

      Note: See s. PSC 113.0926 (2) for accuracy requirements for meters operating in the reverse-registration mode.

2. (2) Polyphase meters shall have their stators in balance within 2% at 100% load at unity and at approximately 50% lagging power factor.
3. (3) Meters used with instrument transformers shall be adjusted, if necessary, so that the overall accuracy of the metering installation will meet the requirements of this rule.

History

History: Cr. Register, July, 2000, No. 535, eff. 8-1-00; CR 02-027: r. (4), Register December 2002 No. 564, eff. 1-1-03.