How to Choose the Right SPD for Your Electrical Panel

Buying a surge protective device (SPD) isn’t as simple as picking one off the shelf. To be effective, it needs to match your system’s voltage, type, and layout. Here’s how to make the right choice.

Step 1: Know Your System Voltage

Common residential panels are 120/240V, while commercial or industrial settings may use 277/480V. Always match your SPD rating to the system.

Step 2: Panel Location Matters

Use Class I SPDs for main panels and Class II for subpanels. Class III is ideal for device-level protection.

Step 3: Understand Surge Capacity

Measured in kA, surge capacity indicates how much energy the SPD can handle. Higher ratings are better for areas prone to lightning.

Step 4: Consider Form Factor

Some SPDs mount directly to a breaker slot, while others need external enclosures. Choose based on your panel’s space and layout.

Conclusion: Selecting the right SPD ensures full system protection and long-term safety. When in doubt, consult an electrical professional.