“Dirty power” is an abnormality in the quality of power delivered to a system. Abnormalities can include low power, variations in voltage and frequency, and surges. All electrical systems are based on a supply of power at a certain voltage and frequency.
Dirty power or electrical noise is any electrical current that varies by more than 10% from the usual 120 volts. Dirty power refers to variations in voltage or current that are often random, usually of relatively low amplitude, and always undesirable. It is an abnormality in the power quality that is being delivered to a system. These abnormalities can include power spikes, sags, brownouts, low power factors, voltage variations, frequency variations, and surges which can ruin expensive equipment.