For example, to work with a plastic enclosure that has a membrane keypad, an LCD, several data cables, and a power cord, the designer should identify all discharge points, even metallic surfaces that are not visible. Allow an air path of 2 cm long minimum. Close air gaps with bonding or gasketing at least 0.5 cm wide to ensure adequate path blockage. Discharge through materials should also be considered. Dielectric breakdown voltage varies with material and thickness.
Most plastics used for electronic enclosures withstand static voltages without arcing through.
This is not necessarily true, however, for thin plastic membranes. Keypad membranes may break down, depending on dielectric and thickness. It is crucial to ensure that the plastic will withstand the desired voltage. Therefore, even if equipment passes the mandated 8-kV test, it may still fail to operate in the field. In addition, if the static voltage rises high enough to cause organic material to break down, a permanent carbonized path is left behind.