Transient Voltage Surge Suppressor (TVSS) is a protective device for limiting transient voltages by diverting or limiting surge current. It is a one-port device that is tapped to the ungrounded conductors, the grounded conductor and the equipment grounding conductor. They are also required to be installed on the load side of the first overcurrent device of the building and they help to protect sensitive electrical equipment from voltage surges and impulses. Transient voltage surge suppressors can be installed on grounded electrical systems operating under 600 volts. This device clamps transient voltages by absorbing major portion of the energy.