Meets 18th Edition IET Wiring Regulations Amendment 2 requirements - Transient Overvoltage Protection - 443.4.1 SPDs In All Installations Overvoltage protection devices (SPDs) are now required in all installations however, in some cases the owner can opt out and accept all risks from such overvoltage's. The CED Axiom Triple Pole + 1 SPD Deice 40KA is designed to give protection for fatal electric surge by reducing to “safe” levels the value. It also protect household and commercial distribution systems. This units disconnects both line and neutral going feeds on trip with 30mA tripping current.