What causes fluctuation in line voltage?

Updated April 17, 2017

Do you experience flickering or dimming lights in your house or office? Have you been frustrated by computer crashes or restarts? Do your light bulbs seem to have a shorter than normal life? Are your kitchen appliances exhibiting problems? Are you having problems with electric motors failing to start or slowing down? Each of these problems can be traced to inadequate or fluctuating line voltages, but what causes these electrical ups and downs?

Power Distribution

Increasing demands for electric power have caused existing power grids to become overloaded. Overloading is a common cause of line voltage fluctuations. Inadequate power generation and inadequate distribution systems are also causes of line voltage problems. Improper or poorly designed power regulating devices may create voltage fluctuations.


Throughout the areas where it is common, lightning is a frequent cause of changes in line voltage. Lightning causes voltage fluctuations through direct strikes on power lines or indirect strikes that are close to power lines. The effect of lightning on power lines is magnified by poor grounding of the power line system.

Installation and Wiring

Installing the wrong size or type of wiring is often the cause of fluctuating line voltages. Wire runs that are too long may cause voltages to fluctuate. Too many pieces of electrical equipment on a single circuit can pull voltages down and cause them to increase or decrease. Incorrect circuit breakers and overloaded transformers may create variations in line voltage.

Connections and Infrastructure

Loose or corroded connections at the electric service user end can create voltage irregularities. The same conditions on the distribution power lines may also affect voltage. Many voltage fluctuation problems can be traced back to inadequate infrastructure.

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About the Author

Ned Millis has been published in "Tennis Industry Magazine," "Golf Industry Magazine," "Sales Management Magazine" and other trade publications. He is a graduate of Claremont Men's College.