Surge Arresters conduct lightning surges around the protected insulator so that a lightning flashover is not created. They are designed to be installed functionally in parallel with the line insulator. The arrester conducts the lightning surges around the protected insulator so that a subsequent 60 Hz fault on the circuit is not created. The arrester becomes a low ohmic path for the surge as voltage across it increases. When the voltage returns to normal, the arrester once again returns to a high ohmic device with only microamps of leakage current.

If an arrester experiences a surge higher than it is capable of handling without failure, and it is failure, equipped with an isolating device, it will isolating device, disconnect during the event.

After the surge is over, and fault current starts to flow, the disconnector senses the fault and ignites the powder built into the device.

The disconnecting device is not an interrupter so during this rare event, an interrupting device must clear the circuit.