Type 1 vs. Type 2 Surge Protective Devices: Which One Do You Need?

Surge Protective Devices (SPDs) are categorized into various types based on their installation location and functionality. The two most common are Type 1 and Type 2. Understanding their differences is crucial for effective surge protection.

What Is a Type 1 SPD?

Type 1 SPDs are installed at the main service entrance. They are designed to handle high-energy surges caused by direct lightning strikes. These devices can protect the entire electrical installation before the main breaker.

What Is a Type 2 SPD?

Type 2 SPDs are installed downstream from the main distribution board, usually on sub-panels. They protect sensitive electronics and appliances from internal switching surges and residual lightning energy.

Which Should You Choose?

If your area experiences frequent lightning storms, a Type 1 SPD is essential. For general protection inside buildings, Type 2 SPDs offer the best value and versatility. In many cases, using both provides layered defense.

Choosing the correct SPD type enhances safety, protects devices, and complies with electrical codes.