The term static electricity is somewhat misleading because it implies that it is unmoving. Perhaps it is more accurately expressed as frictional electricity because it results from the contact of two surfaces. Chemical bonds are formed when any surfaces contact and the atoms on one surface tend to hold electrons more tightly. The result is the “theft” of electrons. Such contact produces a charge imbalance by pulling electrons from one surface to another. As electrons are pulled away from a surface, the result is an excess of electrons (the result is a negative charge) and a deficit in the other (the result is a positive charge).
The extent of the charge differential is, of course, measured in voltage. Although the surfaces with opposite charges remain separate, the charge differential will exist. When the two polarities of charge are united, the charge imbalance will be canceled. Static electricity is an everyday phenomenon, as described in examples in the opening to this chapter. It usually involves voltages of over 1,000V and perhaps rising to as much as 50,000V. A fuel tanker trailer towed by a highway tractor steals electrons from the air as it is hauled down the highway (as does any moving vehicle) and can accumulate a significant and potentially dangerous charge differential. This charge differential, which can be as high as 40,000V, must be neutralized by grounding before any attempt is made to load or unload fuel. Failure to ground a fuel tanker before loading or unloading could result in an explosion ignited by an electrostatic arc.