Split load AFDD board

[Zdb]

Just seen that Screwfix are selling AFDDs for £200+

https://www.screwfix.com/p/wylex-40...WUzod4PNZKb-wwrOVyd-2QopGUgHwpZBoCuO0QAvD_BwE

Now I know that ideally every circuit should have it's own AFDD but hypothetically could we not just split the board between two like with split load RCD boards? They incorporate RCD protection so in theory this proposed method would provide more protection than before and therefore be safer?

Opinions please

 

[westward10]

Interesting to read in my link above these devices would appear to be blind to a fault on a ring final circuit.

 

[Midwest]

I’ve read previously that they self test on installation & periodically afterwards.

Also they will detect faults on appliances connected to an RFC.

 

[Pete999]

I’ve read previously that they self test on installation & periodically afterwards.

Also they will detect faults on appliances connected to an RFC.

Good question, I went to the NICEIC 18th Cinema Launch earlier on last year, and asked the very same question regarding AFDDs ability to detect faults on a RFC, the answer I got was a resounding No. Anyone else hear that? I"m sure many Members attended this show as it was free, albeit losing a morning out of your busy work schedule.

 

[HappyHippyDad]

OSG 3.8 Regulation 421.1.7 and 527.6 I would read these Regs before going to the expense of using AFDDs, as they are only a recommendation as extra protection against fire, as far as I can see.

Does anyone know where this regulation is? The OSG (page 45) points us to regulation 421.1.7 and 537.6, I can find the former but 537.6 is not there, it only goes up to 537.4.4.

 

[hasel5]

How many Domestic Householders will go for that option as end of day
Its a big cost on any job . I can see Housing Associations adopting it as a knee jerk reaction though

 

[HappyHippyDad]

What you need to know about Arc Fault Detection Devices (AFDD’s) - https://www.electriciancourses4u.co.uk/useful-resources/what-you-need-to-know-about-arc-fault-detection-devices-afdds/

That's an interesting article Westward, thanks.

One question.. In the article under the heading 'Do I need to have AFDD's fitted?', it gives a list of premises where they are recommended, it words it as if this list is in BS7671. Do you (or anyone) know where this reg is? It's not 421.1.7 and I cant find the other reg related to AFDD's as 537.6 doesn't seem to exist.

 

[Richard Burns]

The list of premises where AFDDs can be used (not recommended to be used) is at the end of regulation 421.1.7 on the next page and the regulation you give as 537.6 and Pete as 527.6 is probably 532.6.
Look up AFDD in the index.

 

[HappyHippyDad]

The list of premises where AFDDs can be used (not recommended to be used) is at the end of regulation 421.1.7 on the next page and the regulation you give as 537.6 and Pete as 527.6 is probably 532.6.
Look up AFDD in the index.

I'll reword that for you Richard.

"The list of premises where AFDD's can be used is regulation 421.1.7, you just needed to take the extra second to look over the page. As for the other regulation you are looking for that is what an index is for, it clearly states it and is easy to find."

But as usual you are polite and professional Richard and chose not to make me look foolish, thankyou.

 

[Pete999]

Does anyone know where this regulation is? The OSG (page 45) points us to regulation 421.1.7 and 537.6, I can find the former but 537.6 is not there, it only goes up to 537.4.4.

BYB or BBB? Which are you looking at?

 

[westward10]

BYB or BBB? Which are you looking at?

Can only be the BBB.

 

[Pete999]

The list of premises where AFDDs can be used (not recommended to be used) is at the end of regulation 421.1.7 on the next page and the regulation you give as 537.6 and Pete as 527.6 is probably 532.6.
Look up AFDD in the index.

Correct Richard thanks for the heads up my error sorry Lads

 

[HappyHippyDad]

BYB or BBB? Which are you looking at?

537.6 is no longer in the regs, it's been changed to 537.4. I think the OSG may have got it wrong.

 

[Pete999]

537.6 is no longer in the regs, it's been changed to 537.4. I think the OSG may have got it wrong.

Again?

 

[Lucien Nunes]

these devices would appear to be blind to a fault on a ring final circuit

AFDDs only detect arcs, so if the fault doesn't arc, the AFDD won't know about it. A single break along the length of a ring conductor won't generally arc, because no path to a piece of current-using equipment is broken. But a bad connection at an accessory in the ring might arc where neither leg of the ring is secure in the terminal, and that would be detected, as would anything connected by a plug or FCU, or on a spur. I think the point being made is that the AFDD can't magically detect loss of one of two parallel paths.

And for all the nay-sayers. I appreciate there are multiple forces at work pushing for AFDDs to be specced. But the same was true of RCDs, and MCBs before them, which some people thought were needless complications when a fuse was perfectly adequate. Who needs RCD protection if the earthing is OK? Actually, who needs earthing if the insulation is OK? Just make sure the plant attendant does not use water to cool an overheated dynamo...

 

[Midwest]

Another link, something which has been posted previously;

BEAMA Guide to Arc Fault Detection Devices (AFDDs) - http://www.beama.org.uk/resourceLibrary/beama-guide-to-arc-fault-detection-devices--afdds-.html

Page 15, you'll note that some faults will still be detected off or on an RFC, including equipment connected to.