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421.1.7 Arc fault detection devices conforming to BS EN 62606 are recommended as a means of providing additional protection against fire caused by arc faults in AC final circuits.
If used, an AFDD shall be placed at the origin of the circuit to be protected.
NOTE: Examples of where such devices can be used include: • premises with sleeping accommodation
• locations with a risk of fire due to the nature of processed or stored materials, i.e. BE2 locations (e.g. barns woodworking shops, stores of combustible materials)
• locations with combustible constructional materials, i.e. CA2 locations (e.g. wooden buildings)
• fire propagating structures, i.e. CB2 locations
• locations with endangering of irreplaceable goods.
 
Many thanks! I see in my 17th Ed 401.1 'Scope' states:

"Chapter 41 specifies essential requirements regarding protection against electric shock, including basic protection of persons and livestock. It deals also with the application and co-ordination of those requirements in relation to external influences. Requirements are given for the application of additional protection in certain cases."

Is that the same in the 18th Ed? Note the word "requirements" used three times. This is no place for a waffly "recommend".

What National Grid lawyers insisted on in one document about high voltage transmission line safety for Government, that I was involved with, was to refuse even "recommend" (in case the Government took that as a desire of National Grid and made them pay) and insisted instead on "if further protection (i.e. above BS7671) is desired then (here: the use of AFDDs) should be considered (here: in specific types of locations). (I have put some appropriate words for AFDDs in italics). That makes it clear that it is not a requirement.
 
18th edition wording:
“Chapter 41 specifies essential requirements regarding protection against electric shock, including basic protection and fault protection of persons and livestock. It deals also with the application and co-ordination of these requirements in relation to external influences.
Requirements are given for the application of additional protection in certain cases.”
 
18th edition wording:
“Chapter 41 specifies essential requirements regarding protection against electric shock, including basic protection and fault protection of persons and livestock. It deals also with the application and co-ordination of these requirements in relation to external influences.
Requirements are given for the application of additional protection in certain cases.”

Many thanks! It is inexcusable wording to then include an "it is recommended". I will chase the IET and BSI up about this as the cost of fitting these AFDDs will be quite a lot and will potentially also need a larger CU box. I think it could cause a lot of hassle for decent electricians, especially around Quotes.
 
Many thanks! It is inexcusable wording to then include an "it is recommended". I will chase the IET and BSI up about this as the cost of fitting these AFDDs will be quite a lot and will potentially also need a larger CU box. I think it could cause a lot of hassle for decent electricians, especially around Quotes.

This was discussed in a previous post and I think it was @SparkyChick who came up with the great idea of doing 2 items for a quote. One with AFDDs and one without. Also stating that the regs recommend AFDDs... Then it is up to the customer which to choose.
 
This was discussed in a previous post and I think it was @SparkyChick who came up with the great idea of doing 2 items for a quote. One with AFDDs and one without. Also stating that the regs recommend AFDDs... Then it is up to the customer which to choose.
Yes, I read that - and it is a really good practical idea - but that is extra work and it will still be easy to be undercut by others who dismiss the need, making you look like a shark.
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From: IET Forums - The thousand pound fusebox - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=106311
see the discussion there only a few months ago
19 July 2018 by dustydazzler

I just costed a Crabtree 18th ed consumer unit for a job at the cost to me it's £1085 +vat for afdd/rcd 10 circuits / 20 module board. And that is haggling like heck on the price with my regular London wholesaler , he is working on a 12.5% Margin for himself. That price is possibly subject to go up due to afdd rcd price hasn't been 100% confirmation yet.
Arc fault breakers are readily available across Europe and cost around 120 euros. So they won't just be only a couple quid dearer than an RCBBO. At best they will probably come down to around £50 a unit I reckon.
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Yes, I read that - and it is a really good practical idea - but that is extra work and it will still be easy to be undercut by others who dismiss the need, making you look like a shark.
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From: IET Forums - The thousand pound fusebox - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=106311
see the discussion there only a few months ago
19 July 2018 by dustydazzler

I just costed a Crabtree 18th ed consumer unit for a job at the cost to me it's £1085 +vat for afdd/rcd 10 circuits / 20 module board.
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This is the rock of the IET attitude meeting the hard place of customer price point. If anyone can think of a better method of promoting the unqualified multi-trader in his determination to go cheaper - get in and get out fast; personally I can't.

My apologies; a "preaching to the choir" moment me thinks!
 
Yes, I read that - and it is a really good practical idea - but that is extra work and it will still be easy to be undercut by others who dismiss the need, making you look like a shark.
--------------------------------------------------------------------
From: IET Forums - The thousand pound fusebox - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=106311
see the discussion there only a few months ago
19 July 2018 by dustydazzler

I just costed a Crabtree 18th ed consumer unit for a job at the cost to me it's £1085 +vat for afdd/rcd 10 circuits / 20 module board. And that is haggling like heck on the price with my regular London wholesaler , he is working on a 12.5% Margin for himself. That price is possibly subject to go up due to afdd rcd price hasn't been 100% confirmation yet.
Arc fault breakers are readily available across Europe and cost around 120 euros. So they won't just be only a couple quid dearer than an RCBBO. At best they will probably come down to around £50 a unit I reckon.
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As you say, to change a CU and fit AFDD's then I can't see many customers going for the massive price increase.
Just give them 2 items on a quote. One with AFDDs and one without.
Make it clear that the current regs 'recommend' AFDD's but if they choose not to have them then that is their responsibility. You have recommended that they do have them.
Your arse is covered and it's up to the customer.
If you insist in AFDD's then not many customers will fully understand and go with the cheaper quote from someone who will not fit them.
 
As a total amateur, but keen to learn, I have some concerns over all that is in this thread. I have read extensively on the dangers of cables over exits and exit routes falling down in a fire and causing obstruction to firefighters, but assumed this related to multiple cable types, power, lighting, alarm and data all being in conduit below ceiling height, assuming also that if these cables were above, say, plasterboard ceilings, then the problem didn't arise...at least not until the fire has such a hold that the ceilings collapse, either due to the fire alone, or due to a combination of that and, say, saturation from water from melted plastic water supply pipes. Then, if the cables are led through joists, is that safe, as it will take the fire longer to eat through the timber? If the cables are all clipped direct to the joists, or to rafters above, then the joists have to fail first, if the cables are on the side, not the top? Suppose you use metal clips screwed to the joists? The integrity of that would depend not only on the quality of the joists but also on the screws used to fasten the clips. A screw with 5mm mimimum penetration isn't going to hold as long as a screw with 50mm penetration...
Please note: I do not know the answer, but I am very interested on all views on this. I do have a view that suggests that in a single storey ground-floor building of modest dimensions, the exit time is likely to be so short, and the discovery of fire time equally so, that different considerations apply than for a multi-storey building with multiple occupants. The former is a much lower risk for firefighters entanglement than the latter, imho...is it not the case that there is no "one rule fits all" approach?
 
Maybe not my neatest effort, but re-reading it all, it seems clear to me.
Hopefully, JK will come along soon...
 
Anyway, for discussion...there is no one right answer, and being practical people, you must know what works, and can defend your practices, regardless of any recommendations (as opposed to regulations)
You have to demonstrate that you have thought and designed...if your design is defensible, go for it. Be inventive, be creative, seek a solution that works on a particular job...don't just blindly follow some ideas someone else has promulgated. If you don't think your design will stand up to scrutiny, think again.
 
This was discussed in a previous post and I think it was @SparkyChick who came up with the great idea of doing 2 items for a quote. One with AFDDs and one without. Also stating that the regs recommend AFDDs... Then it is up to the customer which to choose.

This is precisely what my 18th Edition trainer said. Give the customer an option but ensure they have the information required to make a call.
 

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