Our common electric meters are: 0.2S, 0.5, 0.5S, 1.0, 2.0. The smaller the numerical value, the higher the accuracy. Usually the grade of the meter used is marked on the dial of the meter. There is a number in a circle, which is the precision grade. Residential power consumption is mostly 2.0 level, industrial and commercial power consumption commonly has 1.0 level and 0.5 level, while substations with relatively high accuracy requirements will use 0.2 level.

    As shown in the figure above, it is a class 1.0 ammeter with an allowable error of less than (+1%). For every 100 kilowatt-hour electricity, only one degree more or less is allowed. In reality, there may be more users and less users. But in fact, in order to pass the test, the error control is more stringent, which is less than 0.6%. That is to say, the difference of up to 6 degrees of electricity can only be produced by using 1000 degrees of electricity.