An overcurrent event or fault is when the current (amperage) in an electrical circuit exceeds the rated capacity. There are many possible sources for an overcurrent fault such as a short, power cross, surge, etc. These faults can permanently damage the follow-on electronics and may cause serious injury.

Overcurrent protection devies help protect against harmful overcurrent surges, and overtemperature fault. These devices limit the flow of dangerously high current during fault conditions. These devices include:

Overvoltage protection devices are designed to protect not only telecommunications circuits but also maintenance personnel and subscribers. When an overvoltage event occurs, the overvoltage device changes its impedance to divert current around the protected circuit to ground. These devices include: