Abstract: The reverse connection of the live and neutral lines of a single-phase electric energy meter may constitute a typical bridge circuit. This paper started with the branch circuit at the access point of the electric energy meter, through equivalence and simplification, and then from simple to complex, from local to the whole low-voltage system, comprehensively analyzed the influence on the metering state of equivalent bridge circuit operating conditions, three-phase asymmetric operation and multi-point grounding or leakage; And the relationship between the measured power and the load of the electric energy meter is described with a binary function, which makes the estimate and analysis of metering state clearer and has a certain practical value for the electricity management personnel. It also has certain reference for electric energy meter manufacturers.