20kA Surge Protection Device: 2026 Contractor Guide
A 20kA surge protection device is the practical choice for sub-distribution boards, small commercial premises and residential panels in lower-exposure locations, yet the rating itself is widely misread. This 2026 guide is written for electrical contractors and panel builders who specify these devices on real projects. It explains what 20kA refers to on a datasheet, separating nominal discharge current from maximum discharge current on the 8/20 microsecond waveform, and shows where the device belongs in a distribution scheme. It covers the companion specifications that matter as much as kA rating, including Uc, Up, response time and backup breaker selection, and sets out installation rules on lead length, coordination and earthing arrangement. A dedicated section identifies the upgrade triggers that mean 20kA is no longer sufficient.
