N.M. Admin. Code § 17.9.560.14

Current through Register Vol. 35, No. 23, December 10, 2024

Section 17.9.560.14 - INSPECTION AND TESTS

A.Request tests: Upon request by a customer the utility shall test the meter serving that customer. The utility shall advise such customer that they may be present during the meter test. If the meter has been tested within the last 18 months the utility may charge the customer the applicable amount provided for in its filed rules, such charge to be refunded to the customer whenever the meter proves to be in excess of two percent in error.

(1) The customer or their representative may be present when their meter is tested if such customer's request to be present is made at the time of their request for the meter test. The utility shall give the customer reasonable advance notification as to the day, time, and place of the test.

(2) A report of the test results shall be made to the customer within a reasonable time after the completion of test, and a record of the report together with a complete record of each test shall be kept on file at the office of the utility for as long a period as prescribed in Subsection K of 17.9.560.14 NMAC.

B.Pre-installation inspections and tests:

(1) Every meter not certified by the manufacturer shall be inspected and tested in the utility's meter shop before being placed in service, and the accuracy of each of these meters shall be adjusted to be within the tolerances permitted by Subsection H of 17.9.560.14 NMAC.

(2) If a meter is physically removed from a customer's premises except for field testing and has not been tested during the preceding thirty-month period, it must be returned to the utility's meter shop and inspected and tested as above before it is again placed in service.

C.Post-installation inspections and tests: The utility shall employ such qualified personnel and shall conduct such post-installation inspections as may be necessary to insure an overall accuracy within two percent of the condition as prescribed in Paragraph (6) of Subsection H of 17.9.560.14 NMAC in the following installations:

(1) meters with associated instrument transformers and phase shifting transformers;

(2) kilovar-hour meters, if associated with instrument transformers;

(3) demand meters, if associated with instrument transformers; and

(4) direct current watt-hour meters;

(5) The commission may order inspections when in its opinion such inspections are necessary.

D.As-found tests: All meters shall be tested after they are physically removed from service if they have not been tested during the preceding thirty-month period. Excepted are those meters damaged beyond testing. Such tests shall be made before the meters are adjusted, repaired, and calibrated. It will not be mandatory to test meters scheduled for retirement unless there is cause to suspect that there will be a subsequent complaint involving the accuracy of the meter.

E.In-service performance tests:

(1) General: In-service performance tests must be made in accordance with Paragraph (2) of Subsection E of 17.9.560.14 NMAC. These tests may be made on the customer's premises or in the utility's meter shop. All self-contained single-phase meters and three-wire network meters on a utility's system must be tested in accordance with Subparagraphs (a) through (e) of Paragraph (2) below.

(2) Periodic test schedule: In the test intervals specified below the word "years" means calendar years and the word "months" means calendar months. The basic periodic test interval shall not be longer than provided for in the following schedule.

(a) Alternating current watt-hour meters:

(i) meters used with instrument transformers: polyphase meters - at least once in four years, and single-phase meters - at least once in eight years;

(ii) self-contained polyphase meters - at least once in six years;

(iii) self-contained single-phase meters - at least once in eight years.

(b) All self-contained single-phase meters and three-wire meters must be tested in accordance with any one of the following listed permissive test programs referred to in 8.1.8 of the standard code for electricity metering, ANSI standard C-12-1965:

(i) periodic interval program;

(ii) variable interval program;

(iii) statistical sampling program.

(c) Variable interval and statistical sampling programs can be used only when specifically approved by the commission and when in accordance with the specific program adopted by commission.

(d) Var-hour meters: same as the schedule for associated watt-hour meters.

(e) Demand meters:

(i) block-interval non-recording demand meters and registers - same as the schedule for associated watt-hour meters;

(ii) block-interval graphic watt-hour demand meters - two years;

(iii) block-interval pulse-operated recording demand meters - two years;

(iv) lagged-demand meters - same as the schedule for associated watt-hour meters.

(f) Secondary standards:

(i) portable rotating standard watt-hour meters - 12 months;

(ii) indicating voltmeters - 12 months;

(iii) instrument transformers - 10 years.

(g) working standards and instruments.

(i) portable rotating standard watt-hour meters - one month;

(ii) indicating voltmeters - six months;

(iii) instrument transformers - 10 years.

F.Instrument transformer tests: All instrument transformers shall be tested in accordance with the applicable procedures of American standard requirements, terminology and test code for instrument transformers, ANSI standard C-57.13:

(1) when first received except in cases where a certificate of test is furnished by the manufacturer;

(2) when removed from service if there is subsequently found to be visual evidence of damage;

(3) upon complaint;

(4) while still in service if there is visual evidence of damage; and

(5) whenever an approved check, such as the variable burden method in the case of current transformers, made whenever the meter was tested indicated that a quantitative test is required.

G.Generating station meter tests: Each generating utility may establish its own test procedures to insure the accuracy of its generating station output watt meter and watt-hour meters as per Subsection A of 17.9.560.13 and Subsection K of 17.9.560.14 NMAC.

H.Test procedures and accuracies: Meters shall be tested at the loads indicated below and adjusted as close as practicable to zero error when found to exceed the tolerances prescribed below. The test of any meter shall consist of a comparison of its accuracy with the accuracy of a standard. The commission will use the applicable provisions of the latest edition of the American standard code for electricity meters, ANSI standard C-12, as criteria of accepted good practice.

(1) Alternating current watt-hour meters:

(a) Shop tests:
Test Load as Approximate Percentage of Test Current*	Power Factor	Tolerances
100	1.0	+1.0%
10	1.0	+1.0%
100	0.5	+1.5%
(b) Field Tests:
100	1.0	+1.0%
10	1.0	+1.0%
*For meters used with current transformers the current at heavy load shall be approximately one hundred percent of the secondary rating of the current transformers and at light load approximately ten percent of that rating.

(2) Direct current watt-hour meters:

Test Load as Approximate

Percentage of Test Current

Power

Factor

Tolerances

100

+1.5%

(3) Demand meters:

(a) Integrated (block interval) demand meters:

(i) Demand meters which are direct driven shall be tested at a load point no less than fifty percent of full scale. Tests shall be continuous for at least one demand interval and shall be started simultaneously with the demand interval of the demand meter.

(ii) Demand meters which are actuated by impulses shall be tested by transmitting enough impulses to cause the meter to register at a load point no less than fifty percent of full scale. If an impulse-actuated demand meter is equipped with a device which records the number of impulses received by the meter, and if there is frequent and accurate comparison of such record with the number of kilowatt hours registered on the associated watt-hour meter, then it is not necessary to make a periodic field test of the demand meter.

(iii) Demand meters shall be adjusted to indicate zero under no-load conditions and shall be checked to ascertain that the meter resets to zero.

(iv) Impulse devices associated with demand meters must be checked for proper operation.

(v) The demand meter shall have an accuracy of within two percent of full scale.

(vi) The time interval must be accurate within half a percent for synchronous motor timing elements and within two percent for mechanical clock timing elements.

(vii) Meters recording demand reading on a chart which provides a record of the time at which the demand occurs shall be accurate to within plus or minus four minutes in 24 hours.

(b) Lagged demand meters:

(i) Demand meters shall be tested at a load point no less than fifty percent of full scale.

(ii) Demand meters shall be adjusted to indicate zero under no-load conditions with potential applied.

(iii) The demand meter shall have an accuracy within three percent of full scale.

(iv) Meters recording demand readings on a chart which provides a record of the time at which the demand occurs shall be accurate to within plus or minus four minutes in 24 hours.

(4) Transformers:

(a) All current and potential transformers shall be tested in accordance with the applicable procedures prescribed in ANSI standard C-57.13.

(b) Any utility unable to perform the above tests due to a lack of proper equipment may have its instrument transformers tested by another utility or laboratory whose testing conforms to the requirements of the commission.

(c) In lieu of the utility testing of instrument transformers the commission will accept the certificate of test as furnished by the manufacturer.

(d) Current or potential transformers shall not be installed if their accuracy does not fall within the 0.6 accuracy class as described in ANSI standard C-57.13.

(5) Meters for measurement of purchased electricity: Utilities purchasing electricity from non-utilities or from utilities outside the state must see that the instruments and meters which are necessary to furnish complete and accurate information as to the energy purchased are installed and tested in accordance with the requirements of the commission.

(6) General:

(a) All meters when tested shall be adjusted as closely as practicable to the condition of zero error.

(b) All tolerances are to be interpreted as maximum permissible variations from the condition of zero error. In making adjustments no advantage of the prescribed tolerance limits shall be taken.

(c) Meters shall not "creep," i.e., there shall be no continuous rotation of the moving element of a meter at a speed in excess of one revolution in 10 minutes when the meter load wires have been removed and voltage is applied to the potential elements of the meter.

I.Facilities and equipment for meter testing: Each utility shall maintain a meter shop or shall have the services of a meter shop available to it for the purpose of inspecting, testing, and repairing meters. The shop shall be open for inspection by authorized representatives of the commission at all reasonable times, and the facilities and equipment as well as the methods of measurement and testing employed shall be subject to the approval of the commission. The meter shop used by a utility shall have adequate and sufficient testing equipment to comply with this rule and to conduct the tests and make repairs and adjustments in compliance with this rule.

(1) Each location at which the shop conducts tests of meters shall have a three-phase voltage supply, one phase of which shall be variable from zero volts to 270 volts.

(2) Standards: Extreme care shall be exercised in the handling of standards to assure that their accuracy is not disturbed. Each meter shop shall contain facilities for protected storage of the secondary standards which are accessible only to personnel specifically so assigned by the utility management.

(a) Secondary standards:

(i) Each shop shall have at least one indicating voltmeter with a stated accuracy within one-quarter percent of full scale. This instrument must be maintained within its stated accuracy.

(ii) Each shop shall have at least one portable rotating standard watt-hour meter with a correction of not more than one-half percent at commonly used loads. If the correction percentage varies between successive tests by more than one-quarter percent, a complete check must be made to determine the cause of such variation. If the cause of variation cannot be removed the use of the instrument should be discontinued.

(iii) Secondary standards shall be checked periodically (See Paragraph (2) of Subsection E of 17.9.560.14 NMAC) at the national bureau of standards or at a laboratory acceptable to the commission. Secondary standards otherwise shall be kept in the protected storage of the meter shop at all times.

(iv) Secondary standards shall be accompanied at all times by a certificate or calibration card, duly signed and dated, on which are recorded the corrections required to compensate for errors found at the customary test points at the time of the last previous test.

(b) Working standards: Each shop shall have at least one portable rotating standard watt-hour meter with a correction of not more than one-half percent at commonly used loads. If the correction percentage varies between successive tests by more than one-quarter percent, a complete check must be made to determine the cause of such variation. If the cause of variation cannot be removed the use of the instrument should be discontinued. Working standards shall be checked periodically (See Paragraph (2) of Subsection E of 17.9.560.14 NMAC) by comparison with a secondary standard from the protected storage of the meter shop.

J.Records of meters: Each utility shall maintain records of the following data, where applicable, for each meter until retirement:

(1) the complete identification (number, type, voltage, amperes, number of wires, disk constant (kh), demand interval, and ratio); and

(2) the dates of installation and removal from service together with the location.

K.Meter test records: Each utility shall keep meter test records until a superseding test has been made but not less than two years or as may be necessary to comply with service rules regarding refunds on inaccurate meters. Test records shall include the following:

(1) the date and reason for the test;

(2) the reading of the meter before making any test;

(3) the accuracy "as found" at light and heavy loads;

(4) the accuracy "as left" at light and heavy loads; and

(5) a statement of any repairs made.

N.M. Admin. Code § 17.9.560.14

6-30-88; 17.9.560.14 NMAC - Rn, NMPSC 560.34-560.44 & A, 6-15-05, Adopted by New Mexico Register, Volume XXXI, Issue 21, November 10, 2020, eff. 11/10/2020