Type 1 units go at the service entrance and stop the biggest surges. Type 2 and Type 3 devices protect at distribution panels and near important equipment. Without proper surge protection, these spikes can severely damage sensitive electronics, appliances, and electrical systems. SPDs offer a critical defense by diverting excess voltage away from protected devices, ensuring their safety and extending their lifespan. This article will explore the. Surge protectors (Surge Protective Devices, SPD) installed in distribution board panels are primarily used to protect electrical equipment from transient voltages (surges or spikes) caused by lightning strikes, power grid fluctuations, or other factors. The. The three main types of SPD are Type 1 SPD, Type 2 SPD, and Type 3 SPD.