- The Threat — A sag is a decline in the voltage level. Also known as “brownouts,“ sags are the most common power problem
- The Cause — Sags can be caused locally by the start-up demands of electrical devices such as motors, compressors, and elevators. Sags may also happen during periods of high electrical use, such as during a heat wave.
- The Effect — Sags are often the cause of “unexplained“ computer glitches such as system crashes, frozen keyboards, and data loss. Sags can also reduce the efficiency and lifespan of electrical motors.
- The Threat — A blackout is a total loss of power.
- The Cause — Blackouts are caused by excessive demand on the power grid, an act of nature such as lightning or an earthquake, or a human accident such as a car hitting a power pole or a backhoe digging in the wrong place.
- The Effect — Of course a blackout brings everything to a complete stop. You also lose any unsaved data stored in RAM and may even lose the total contents of your hard drive.
- The Threat — A spike, also called an impulse, is an instantaneous, dramatic increase in voltage.
- The Cause — A spike is usually caused by a nearby lightning strike but may also occur when power is restored after a blackout.
- The Effect — A spike can damage or completely destroy electrical components and also cause data loss.
- The Threat — A surge is an increase in voltage lasting at least 1/120 of a second.
- The Cause — When high-powered equipment such as an air conditioner is powered off, the excess voltage is dissipated though the power line causing a surge.
- The Effect — Surges stress delicate electronic components causing them to wear out before their time.
- The Threat — Electrical noise, more technically called electromagnetic interference (EMI) and radio frequency interference (RFI), interrupts the smooth sine wave expected from electrical power.
- The Cause — Noise has many causes including nearby lightning, load switching, industrial equipment, and radio transmitters. It may be intermittent or chronic.
- The Effect — Noise introduces errors into programs and data files.