To understand the importance of surge protectors, one only has to consider the changing nature of household appliances. Computers and other complex devices have set a new standard of quality in electricity itself, and old-style power is too variable and uncertain for the modern household.
There was a time when the term “household appliances” mainly meant simple motorized devices. Mixers, vacuum cleaners, fans and other such machines can function without precise voltage regulation, and the slight fluctuations that typically plagued municipal power supplies were scarcely noticed. Televisions and radios were also able to function through slight variations in voltage. Homes had fuses or circuit breakers to guard against lightning strikes, and that was enough.
Decades have passed, and today’s appliances are a different breed. Computers require more precise voltage regulation, and sudden fluctuations can lose data or render the device completely inoperable. Many home systems such as climate control and security are also computer regulated and need constant voltage.
Power companies make an effort to control their voltage as closely as possible, but their abilities are limited in this regard. Nature also makes electricity in the form of lightning and other phenomena, and our power grids will always be vulnerable to surges from those sources. Since it is impossible to eliminate the surges, it is necessary to protect our devices. The machines providing that protection are called surge protectors.
A surge protector works like the drain on a bathtub. A tub has a little lever to pull up the plug, and that lever is set in a round fixture with a small hole in the bottom. If the bath water rises to that level, it drains out through the hole and does not rise any higher in the tub.
A surge protector does this with electricity. When the power reaches a set limit, the surge protector drains off the excess and sends it to the outlet’s grounding wire. This prevents the power going to appliances from rising too high and causing damage.
A conductor is needed for the connection between the “hot” wire and the ground wire. This conductor may be composed of metal or gas, depending on the brand.
Some surge protectors use metal connectors called metal oxide varistors or MOVs. They work on the principal that some metals change their electrical conductivity according to the amount of power flowing through them. When the voltage is low, the electrons in the MOVs cause very high resistance, and none of the power can flow through them. When the voltage rises above an acceptable level, the metal’s resistance suddenly drops and the excess electricity flows through the MOVs into the ground wire.
Other surge protectors connect the hot wire to the ground wire using a tube filled with gas. This gas normally has a high resistance, and power is unable to flow through it. When the power exceeds the acceptable limit, the gas ionizes and loses its resistance. Excess power is then able to flow through it into the ground wire.