SPD vs Thunder Arrestor: Key Electrical Safety Differences SPD vs Thunder Arrestor: Understanding the Difference & Similarities Breezent Electric | Igniting Skills, Wiring Dreams ⚡ Introduction When it comes to protecting your electrical system, two terms often surface: SPD (Surge Protective Device) and Thunder Arrestor (Lightning Arrester). Though they share similar goals — protection from high voltages — they operate in different ways. Let's break it down. What is an SPD? A Surge Protective Device protects appliances and electrical systems from transient voltage spikes, usually caused by lightning, switching, or grid faults. It redirects excess voltage safely to the ground before it can damage equipment. What is a Thunder Arrestor? A Thunder or Lightning Arrestor is designed to protect structures and equipment from direct lightning strikes . It conducts the lightning current direc...