NEN 1010 §411.3.2
Automatic disconnection of supply (ADS)
Automatische uitschakeling van de voeding
Also known as: afo, afschakeling, automatic-disconnection, beschermende-uitschakeling, protective-disconnection, 411
Automatic disconnection of supply – main protective measure: upon fault to PE, overcurrent protection or RCD must disconnect within required time (≤0.4 s for 230 V final circuits).
Practical example
Automatic disconnection of supply. For a fault on a 230 V final circuit, loop impedance must be low enough for the breaker to trip within 0.4 s; a long cable requires an RCD.
Common mistake
Automatic disconnection of supply Common mistake: Relying solely on the MCB's rated current without measuring loop impedance — excessive Zs results in a tripping time well exceeding the required limit.
See also
Related terms
- PE (Protective Earth)
- Fault-loop impedance
- Prospective short-circuit current
- Four-Pole Switching of the Neutral (TT/IT Systems)
- Fire-Protection RCD (300 mA)
- Fixed Electric Floor Heating — Embedding Requirements
- Working Clearance for Switchgear and Distribution Boards
- Local isolator (appliance disconnector)
- Touch voltage (UL)
In-depth guides
- → Earthing and earthing systems (TN, TT, IT)
- → Automatic disconnection of supply (AUV)
- → §444 EMC — separation of power and data cables (§444)
- → §411.6 IT system — disconnection on a second fault (§411.6)
- → §434 Short-circuit protection & the adiabatic equation — §434
- → NEN-EN 62034 Emergency Lighting — Automatic Test Systems (NEN-EN 62034)
- → §537 / IEC 60364-5-53 Isolation and switching — the four functions of §537 (isolation, emergency switching, functional switching, maintenance switching)
- → §445 (IEC 60364-4-45) §445 — Protection against unintended automatic restart after undervoltage
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