(a)  In determining the average error of a watt hour meter, the following procedure is recommended:

(1)           All meters whenever possible, shall be tested at the following three loads: one‑tenth of the current rating of the meter, normal load and at rating.

(2)           The average of these tests obtained by multiplying the results of the test at normal load by three (3), adding the results of the tests at one‑tenth rating and at the current rating, and dividing the total by five, shall be deemed the condition of the meter.

(3)           In an installation where it is impossible to obtain a load of ten percent (10%) of the rating, or one hundred percent (100%) of the rating of the meter tests shall be made at the nearest obtainable loads to ten percent (10%) and one hundred percent (100%) of the rating of the meter and the values given in the ratios as stated above.

(b)  To determine normal load, use the percentage of connected load indicated below for the class of service metered.


    Percentage of

     Class of Service Metered                                                 Connected Load

Residence and Apartment Lighting                                                   40%

Elevator Service                                                                                   40%

Factories (Individual Drive), Churches and Offices                     45%

Factories (Shaft Drive), Theatres, Clubs, Entrances,

   Hallways, and General Store Lighting                                          60%

Restaurants, Pumps, Air Compressors, Ice Machines

   and Moving Picture Theatres                                                         70%

Signs and Window Lighting and Blowers                                      100%


(c)  When a meter is connected to an installation consisting of two or more of the above classes of load, the normal load would be the sum of the normal loads for each class.