What’s inside a Single module AFDD? - Arc fault detection device Crabtree / Wylex

How do they combine all circuit protection functions into a single DIN rail module? We lift the lid on a single module Crabtree / Wylex AFDD (AFCI) Arc Fault Detection Device to find out what’s inside.

When AFDD's crept into the 18th Edition of BS7671 UK electricians expected consumer units to grow to accommodate the 2 or 3 module devices. The clever boffins at Siemens (owner of Wylex and Crabtree brands) set about shrinking the tech.

This single AFDD breaker includes all circuit protection functions.
MCB - Minature circuit breaker for overcurrent and short circuit protection.
RCD - Residual Current Device for earth fault protection.

Earlier in 2019 Siemens introduced a single module RCBO with the above functions which included double pole isolation of line and neutral conductors.

This new device adds - arc fault detection to the package.

Arc fault technology is a new technology to help prevent electrical faults (ARC's)which can cause fires. BS7671 suggests using them in buildings with sleeping accommodation, timber-framed buildings and high-risk buildings such as museums.

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