Common Power Problems

Types of Power Problems

Below, you will find different types of common power problems, their causes and their effects:


Also known as brownouts. Sags are short-term decreases in voltage levels. This is the most common power problem. Sags are typically caused by the start-up power demands of many electrical devices (including motors, compressors, elevators, shop tools, etc.).

Sags also are the electric utilities’ means of coping with extraordinary power demands.

In a procedure known as “rolling brownouts”, the utility will systematically lower the voltage levels in certain areas for hours or days at a time. Hot days, when air conditioning usage is at its peak, will often prompt rolling brownouts.

The effects of a sag is that it can “starve” a computer of the power it needs to function, causing frozen keyboards and unexpected system crashes with the end result being the loss or corruption of data. Sags also reduce the efficiency and life span of electrical equipment, particularly motors.


Blackouts are total loss of utility power

Blackouts are caused by excessive demand on the power grid, lightening storms, ice on power lines, car accidents, backhoes, earthquakes, power rationing, etc.

The effects of a blackout is loss of current work in RAM or cache, possible loss of hard drive File Allocation Table (FAT) resulting in total loss of data stored on drive.


Also referred to as an impulse. Spikes are instantaneous, dramatic increases in voltage. Akin to the force of a tidal wave, a spike can enter electronic equipment and damage or completely destroy components.

Spikes are typically caused by a nearby lightening strike. Spikes can also occur when utility power comes back on line after having been knocked out in a storm or as the result of a car accident.

The effects of a spike are catastrophic damage to hardware and loss of data.


A surge is a short-term increase in voltage typically lasting at least 1/120 of a second.

Surges are caused by high-powered electrical motors such as air conditioners and household appliances in the vicinity. When this equipment is switched off, the extra voltage is dissipated through the power line.

The effects of surges on computers and similar sensitive electronic devices, which are designed to receive power within a certain voltage range, are stress on delicate components, which cause premature failure.


Noise is more technically referred to as Electro-Magnetic Interference (EMI) and Radio Frequency Interface (RFI). Electrical noise disrupts the smooth sine wave one expects from utility power.

Electrical noise is caused by many factors and phenomena including lightening, load switching, generators, radio transmitters and industrial equipment. It may be intermittent or chronic.

The effects of noise are an introduction of glitches and errors into executable programs and data files.

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