Five Main Power Problems - Definitions, Causes and Effects

This article covers the five main electrical powers many encounter that can damage your equipment or degrade its lifespan.

Table of Content

The Anatomy of a Power Disturbance

Surges, spikes, blackouts and brownouts - what really happens to a computer when it experiences an out-of-bounds power anomaly? We'll use a nearby lightning strike as an example, although it is just one of countless problems that can strike a system.

Lightning strikes a nearby transformer. If the surge is powerful enough, it travels instantaneously through wiring, network, serial and phone lines and more, with the electrical equivalent force of a tidal wave. The surge travels into your computer via the outlet or phone lines. The first casualty is usually a modem or motherboard. Chips go next, and data is lost.

The utility company responds to over-voltages by disconnecting the grid. This creates brownouts and blackouts. If the voltage drops low enough, or blacks out, the hard disk may crash, destroying the data stored on the disk. In all cases, work-in-process stored in cache is instantly lost. In the worst case, password protection on the hard drive can be jumbled, or the file allocation table may be upset, rendering the hard disk useless.


Power Event Definitions, Causes, and Effects

Power Sag

Also referred to as brownouts, sags are short term decreases in voltage levels. This is the most common power problem, accounting for 87% of all power disturbances according to a study by Bell Labs.

  • CAUSE - Power sags are typically caused when high-powered electrical devices are started up. These devices include air conditioners, HVAC units, electric heaters and factory machinery. Power companies use sags to deal with day of high power demands (such as during a summer heat wave). In a procedure known as "rolling brownouts", the power company will systematically lower voltage levels in certain areas for hours or days at a time. Hot summer days, when air conditioning requirements are at their peak, will often prompt rolling brownouts.
  • EFFECT - For high-powered devices, power sags typically have no immediate adverse effect on them. However, for sensitive electronics (such as computers and game consoles), a power sag can "starve" a device of the power it needs to function, and cause frozen keyboards and unexpected system crashes which both result in lost or corrupted data. Prolong exposure to power sags can reduce the efficiency and life span of electrical equipment, particularly motors.
  • PROTECTION - Invest in a quality universal power supply (UPS) to ensure your sensitive electronics receive clean stable power.

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Power Sag
Illustration of power sag from


A blackout is a total loss of electrical power, typically short-term (hours to days).

  • CAUSE - Blackouts are typically caused by excessive demand on the power grid, lightning storms, ice on power lines, car accidents, tripped circuit breakers, earthquakes and other natural events.
  • EFFECT - For sensitive electronics, a sudden loss of power will cause you to lose any unsaved work on your computer. Additionally, data on your hard drive may also be lost if the blackout happens at a point with the hard drive is performing critical write operations.
  • PROTECTION - Invest in a quality universal power supply (UPS) that can continue to provide power your sensitive electronics for the few minutes you need to power them down properly.

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Illustration of power blackout from

Power Spike

Also known as an impulse, a spike is an undesirable momentarily (usually a few milliseconds), dramatic increase in voltage (sometimes thousands of volts). Similar to the force of a tidal wave, power spikes can either reduce the life span of an electronic equipment or potentially damage destroy it or components within it.

  • CAUSE - Spikes are typically caused by a nearby lightning strike, short circuits, or malfunctions at the power company. Power spikes can also occur when the electrical initially comes back on line after the blackout.
  • EFFECT - Computers and other sensitive electronics can be damaged. Data can be lost or become corrupted. Incremental damage that degrades equipment performance and reduces its lifespan.
  • PROTECTION - Invest in a quality surge protector or a universal power supply (UPS) to ensure your sensitive electronics receive clean stable power.
Power Spike
Illustration of power spike from

Power Surge

A power surge is a short term increase in voltage. Unlike a power spike, a power surge typically has less voltages (usually 10% to 35% above the normal line voltage) and can last for a few milliseconds to several minutes. Surges can sometime be preceded or followed by power spikes.

  • CAUSE - Surges result from presence of 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.
  • EFFECT - Computers and other sensitive electronics are designed to receive power within a certain voltage range. Anything outside of expected peak and RMS (considered the "average" voltage) levels will stress delicate components and cause premature failure. It can also cause data corruption or data loss.
  • PROTECTION - Invest in a quality surge protector or a universal power supply (UPS) to ensure your sensitive electronics receive clean stable power.

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Power Surge
Illustration of power surge from


More technically referred to as electro-magnetic interference (EMI) and radio frequency interference (RFI), electrical noise disrupts the smooth sine wave one expects from utility power.

  • CAUSE - Electrical noise is caused by many factors and phenomena, including lightning, load switching, fluorescent lights, generators, radio transmitters and industrial equipment. It may be intermittent or chronic.
  • EFFECT - Noise introduces glitches and errors into computer applications and data files, and can cause system lockups.
  • PROTECTION - Invest in a quality surge protector or a universal power supply (UPS) to ensure your sensitive electronics receive clean stable power.
Electrical Noise
Illustration of electrical noise from

How to Protect Your Equipment?

There are affordable solutions to easily protect your equipment and data against these hazardous electrical problems. Something as simple as a power surge may not seem detrimental and may go unnoticed until equipment fails. Solutions available range from a variety of sizes for different applications that offer varying levels of protection. Whether its for your home, small business, or enterprise environment, there are a variety of surge suppressors, UPS systems, and power distribution units (PDU) from many manufacturers to help you safeguard your equipment.

Read our article here to find out what you can do to protect your computer and network equipment from damaging power disturbances.

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