Before revision: Shorting is done by spark gaps, discharge tubes, zener-type semiconductors, and metal-oxide varistors (MOVs), all of which begin to conduct current once a certain voltage threshold is reached , or by capacitors which inhibit a sudden change in voltage .
After revision: Shorting is done by spark gaps, discharge tubes, Zener effect semiconductors, and metal-oxide varistors (MOVs), all of which begin to conduct current once a certain voltage threshold is reached capacitors which inhibit a sudden change in voltage or by .