AFDD-Protected Bedroom Circuit
A bedroom final circuit on an AFDD-RCBO, feeding a socket and a light — the BS 7671 421.1.7 recommendation for sleeping accommodation, where a fire can start unnoticed.
Components Needed
Text Wiring Path
Live + Neutral → AFDD → Socket → LED Light Earth → Socket (E)
Schematic
Steps
- 1Place Live, Neutral and Earth terminals.
- 2Place an AFDD-RCBO as the single protective device on the final circuit.
- 3Wire Live and Neutral into it at L-in and N-in.
- 4Take L-out and N-out to the double socket, then tap both on to the LED light.
- 5Run Earth directly to the socket's E terminal.
- 6Press Run, then open the AFDD: the whole final circuit goes dead, socket and light together.
Arcs from a loose terminal or a damaged cord carry too little current to trip a breaker, and they are not earth faults, so an RCD ignores them too. An AFDD listens for the signature of a series or parallel arc and opens first — which is why it is specified where people sleep.
Arc-fault devices reduce a fire risk ordinary breakers cannot see; they do not remove it. Loose terminations, damaged flexible cords and overloaded adaptors still start fires — AFDDs are additional protection, not a substitute for sound wiring.
Terms used here
Defined in the glossary — each one opens at its own entry.
Now wire it for real.
Build this circuit in the browser, inject a fault, and watch the protection respond.