An RF or coaxial lightning protecter is a device used on telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. When a lightning surge travels along the coaxial cable to the arrester, the current from the surge is diverted through the arrester, in most cases to ground.

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In telegraphy and telephony, a lightning arrester is placed where wires enter a structure, preventing damage to electronic instruments within and ensuring the safety of individuals near them. 

If protection fails or is absent, lightning that strikes the electrical system introduces thousands of kilovolts that may damage the cable, and can also cause severe damage to the device and other electrical or electronic devices which connected. Lightning-produced extreme voltage spikes in incoming cables can damage electrical home appliances or even produce death