How Does a Surge Protector Work?

By Gregory Hamel

What Is a Surge Protector?

A surge protector is a device which protects electronic devices from the effects of a sudden spike in voltage above what they are designed to handle. Such power surges can render electronic devices inoperable. Surge protectors are plugged into normal electric outlets, and the electronic device to be protected is then plugged into the surge protector. Many surge protectors have several plug in sites, like a power strip, each of which are protected. Not all power strips are surge protectors however--it is a good idea to make sure that the power strip expensive electronic equipment, such as computers and TVs are plugged into are surge protected.

The Operation of a Surge Protector

A surge protector is a fairly simple device. When it is plugged in and some other device plugged into it, the the protector normally acts as a standard power strip or extension cord. When there is a power surge that goes above the level accepted by the surge protector, excess energy is diverted away from the components plugged into the protector via a grounding wire that is attached to voltage sensitive semiconductors. Some surge protectors also have a fail-safe fuse in case too much voltage manages to get through. A fuse is a resistor that will burn up if electricity exceeds a certain level, severing the flow of power.

When Do Power Surges Occur

Surge protectors are an essential component of protection electronic devices from excessive voltage, but knowing how and when surges are likely to occur is also helpful. The most well-known cause of large power surges are lighting strikes, which can send voltage rushing through the energy grid. Trees falling on power lines and animals getting into transformers can also cause surges. Basically, a power spike will be caused by anything that interrupts to flow of electricity or diverts a large amount of power to a certain source that turns on and off. The operation of energy-hogging appliances like refrigerators and air-conditioning systems can cause voltage spikes, as well as smaller devices with motors like blow-dryers or vacuum cleaners. Electronic devices can usually handle spikes caused by normally daily appliances, but during events like a storm or a power outage, it is wise to unplug devices to protect them from large surges, even if they have a surge protector attached.