Recently, the distribution line increases due to unaccounted-for operation of power facility circuit breaker of a distribution line due to consumers" complicated load circuits and facilities. Numerous kinds of facilities are being operated in system state, and when these facilities work, harmonics generated to power system induce malfunction in them and affect the entire system. In most of electric wires, 3-phase 4-wire electric power distribution system is able to use single phase and 3 phase load at the same time. This system results in several problems like uneven load unbalance, low electric quality, reduction and damage of output. In this study, economical and effective measurements of power facility"s harmonics obstacle caused by unbalanced operation of load, the increase of damage in connected system and unstable operation of load are examined. Then, reasons for their occurrence, effects, calculating and measuring methods and the actual status regarding permitted limits were analyzed.