Surge environment assessment per IEEE C62.41, cascaded SPD coordination (Type 1/2/3), voltage protection rating selection, and installation design.

Why does lead length matter for SPDs?

SPD performance degrades dramatically with lead length. Every inch of wire adds inductance, which increases the let-through voltage during a surge. IEEE C62.41 testing shows that 300mm (12 inches) of lead can add 300-600V to the clamping voltage. This is why SPDs must be installed with the shortest possible connections.

Key Deliverables

• Surge environment assessment per IEEE C62.41
• SPD coordination design (Type 1 → Type 2 → Type 3 cascade)
• Voltage Protection Rating (VPR) selection for each level
• SPD specification schedule with ratings and locations
• Installation details (lead length ≤300mm, dedicated breakers)

Type 1 vs Type 2 vs Type 3: what is the difference?

Type 1 (service entrance): handles direct lightning currents, highest surge capacity (≥200 kA). Type 2 (distribution): handles residual surges after Type 1, sized for panel protection (≥50 kA). Type 3 (point of use): final protection for sensitive equipment (≥10 kA). All three levels work together, and the cascade progressively reduces surge energy.