A voltage spike is a short upsurge of voltage intensity that occurs when a surge sustains longer voltage intensity. A power strip, which is sometimes mistaken for a surge protector, uses a male electrical plug outlet and may or may not have a built-in surge protector. Most power strips are clearly labeled.

A common misconception is that surge protectors always protect against lightning, which can create sudden and increased electrical pressure (thousands of volts or greater). Generally, a surge protector has a slight operational delay, but a surge protector fuse can blow during a lightning surge and cut off all current.

Surge protector components and features include:

• An iron core transformer transfers alternating current (AC) power but cannot absorb sudden surges.
• A zener diode protects against common circuit spikes and is sometimes combined with a transient voltage suppression diode.
• If a circuit breaker is out or blows a fuse, a surge protector provides internal protection and protects against device and exterior surges.
• Uninterruptible power supply takes in spikes using a low pass filter and allows external power beyond the battery, which supplies uninterrupted power.
• A metal oxide varistor (MOV) is thermal fused and limits voltage three to four times that of a regular current. Parallel MOV connections expand life expectancy and increase current capacity. If exposed to many large transients or numerous small transients, MOVs can self-destruct.