AFCI in BS7671, and also...

It came up elsewhere, so thought a quick summary of where arc fault circuit interrupters get a mention in the new 18th edition draft.
In the section on prevention of fires caused by electrical equipment:
"421.1.7 Arc fault detection devices conforming to BS EN 62606 may be used to provide additional protection against fire caused by arc faults in AC final circuits."
Then in the :
"532 DEVICES FOR PROTECTION AGAINST THE RISK OF FIRE 532.1 General In locations where, in accordance with Chapter 42, a particular risk of fire exists, preventive protection measures against the risk of fire are required. This may also apply to other locations of the electrical installation, depending on a risk analysis. A suitable evaluation of the risk should be carried out. The selection of protective and monitoring devices shall take into account the nature of the load and the likelihood of the device to operate, e.g. fault currents of higher frequencies, DC fault currents or increased leakage currents. (See also Regulation 331.1.)"
we have:
"532.5    Internal arc fault protection in a switchgear and controlgear assembly Where required for special applications, internal arc fault protection (e.g. optical detection system) detecting a fault arc together with a protection system can be selected in order to extinguish the arc. Alternatively, an assembly with arc ignition protected zone(s) can be selected to minimise the risk of an arcing fault. (Arcing class I in accordance with PD EEC/TR 61641.) NOTE: Internal arc fault protection is typically associated with a switchboard used in special applications. An assembly that has been subject to an internal arcing fault can require maintenance or replacement. 532.6    Arc fault detection devices (AFDD) Where specified, arc fault detection devices shall be installed: at the origin of the final circuits to be protected, and in AC single-phase circuits not exceeding 230V. AFDDs shall comply with BS EN 62606. Coordination of AFDDs with overcurrent protective devices, if necessary, shall be in accordance with the manufacturer's instructions."
and that is all she wrote...
Might be worth highlighting that if you sign up for a free BSI account they now have a PDF download version of the draft in addition to the commentable version that only works in a browser. Obviously not the final version, but it is searchable and does of course give you access to the bulk of the 17th edition (and BS7671 is not usually available electronically - even with the library style BSI subscriptions that let you at least view most of the other BS docs)
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Cheers,

John.
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How come this sort of thing never appears on R4s book at bedtime, should do wonders for insomnia. Brian
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