The only way to accurately monitor system harmonic is with a device designed specifically for that task. Power quality monitor companies manufacturer a variety of devices to conduct these measurements. It is important to find the source of the harmonic. These relatively inexpensive hand-held meters can help you locate culprit loads.

To measure system harmonics, a larger more costly device will be required. This unit should be placed in the area where harmonic conditions or problems are suspected. Monitoring multiple locations over an extended period of time will provide a profile of the conditions on the distribution network.

Current and voltage profiles should be measured for periods when the circuit is under typical loading. Measurements taken during periods when the circuit is lightly loaded may provide an inaccurate picture of the harmonic conditions.