ELECTRICAL SURGES

A surge is a transient wave of current, voltage or power in an electric circuit. Surges, or transients, are brief overvoltage spikes or disturbances on a power waveform that can damage, degrade, or destroy electronic equipment within any home, commercial building, industrial, or manufacturing facility. 

There are several sources of power surges. They can originate from the electric utility company during power grid switching. Switching transients result from electrical equipment switching operations, fault initiations, and interruptions in a power distribution system.

Other sources of electric surges are within the home or facility and these are termed internal sources for instance; switching of electrical loads, magnetic and inductive coupling and static electricity.

Externally the most recognizable source of surges generated outside the home or facility is lightning. Lightning surges are the result of a direct flash terminating on the power system, structures, or to the soil, and can also be induced on the utility system and distribution circuits by nearby lightning flashes.

Cloud-Ground Lightening Strike

Lightning is a natural phenomenon caused by separation of electrical positive and negative charges by atmospheric processes. Lightening is usually comprehended through damage it causes at the point when a cloud-ground stroke terminates on a tree, structure, or elevated wiring. This is generally called a lightning strike. Unless the struck items are protected from lightning, the results of the strike are often visible and lasting. But the lightning current pulse continues into conductive parts of the structure, cables, and even underground wiring and pipes. Because the initial lightning impulse is so strong, equipment connected to cables a mile or more from the site of the strike can be damaged.

Surge protective devices applied at the service entrance mains of residential AC power circuits will be subjected to normal and abnormal surge conditions as well as abnormal AC voltage conditions. The design of the application must consider these conditions to prevent premature degradation and failure.