Rcd fused connection unit

[Ampo]

Hi all, could I have opinions on the use of rcd fused please.
Customer has old 3036 at the front of the house.
They want a couple points on there new decking for festoon type lighting switch from inside.
There is a t and e switch fed outside light already so I'm thinking of coming off this to an outside rcd fcu which can feed the first set of lights and then swa to the next standard fcu (fed from load side of the first).

The client wanted sockets instead of spurs but I have said this isn't possible without finding the ring circuit inside the house so they will have to choose non transformer lights.

This will ensure all new stuff is protected. My issue is with the rcd not being to 61008 or 61009. I'm sure I've read that this is a problem but I'm looking at the big book and can't find it

 

[loz2754]

The issue with RCD sockets and RCD FCUs is that they fall under BS EN 7288, which is not listed among the allowable standards. There is not a regulation that says we cannot use them.
There has been much debate, but if I recall correctly, most are in favour of not using them for additional protection, as they don't meet the requirements for additional protection.

 

[westward10]

For the requirements of BS7671 an rcd spur does not satisfy as a device for providing additional protection. You would have to list it as a departure a prove its use provides the same level protection as that required by BS7671.

 

[loz2754]

Just to add that we can't allow ourselves to be swayed by what the customer wants, if we can't do what they want within acceptable standards and regulations.
I would either find a way to do the job that's within the regulations, or walk away and let someone else do the job.

 

[Dartlec]

The issue with RCD sockets and RCD FCUs is that they fall under BS EN 7288, which is not listed among the allowable standards. There is not a regulation that says we cannot use them.
There has been much debate, but if I recall correctly, most are in favour of not using them for additional protection, as they don't meet the requirements for additional protection.

I believe there was an article in "Connections", the NICEIC magazine, that states that 7288 RCDs are considered acceptable as additional protection in the NICEIC's view. (Though it is as pointed out a deviation from BS7671 at the moment).

What that opinion is worth is up to the installer I guess - I did save a copy for reference so I'll see if I can find it...

 

[loz2754]

There's more on this in this previous thread:
The Connections article is in post 13.

C2 on EICR due to RCD Protection | on Free Electrical Advice - Electricians Forums

Find C2 on EICR due to RCD Protection Advice and Help. How-to C2 on EICR due to RCD Protection in the Periodic Inspection Reporting & Certification advice boards on ElectriciansForums.net | Free Electrical Advice - Electricians Forums: Electricians' Talk Forums. C2 on EICR due to RCD Protection...

www.electriciansforums.net

 

[Dartlec]

There's more on this in this previous thread:

C2 on EICR due to RCD Protection | on Free Electrical Advice - Electricians Forums

Find C2 on EICR due to RCD Protection Advice and Help. How-to C2 on EICR due to RCD Protection in the Periodic Inspection Reporting & Certification advice boards on ElectriciansForums.net | Free Electrical Advice - Electricians Forums: Electricians' Talk Forums. C2 on EICR due to RCD Protection...

www.electriciansforums.net

That has the screenshot I obviously saw, though also some conflicting advice from elsewhere ?‍

Though it seems there has been a new version of the standard BS 7288 standard (2019 previously 2016) that has more onerous requirements, but without access to the standards I have no idea if it's made them more or less suitable..

Anyone notice if they put them back in for the DPC for AMD 2?

 

[Ampo]

Just to add that we can't allow ourselves to be swayed by what the customer wants, if we can't do what they want within acceptable standards and regulations.
I would either find a way to do the job that's within the regulations, or walk away and let someone else do the job.

Absolutely agree, and I have a reputation in my area to uphold. Its also important from the other side of the coin though where I'm not looking to inflate unnecessary work off pensioners. Its a balancing act. In this instance if it can't be done simply they will go without, no budget for the db at present unfortunately but I hear what your saying

 

[telectrix]

why not fit a 61008 adjacent to CU, feed from RFC fuse, and then protect the whole of the RFC; then tap off the RFC for your outside works.

 

[Ampo]

why not fit a 61008 adjacent to CU, feed from RFC fuse, and then protect the whole of the RFC; then tap off the RFC for your outside works.

That may be an option though I'd need to do some additional tests before I put the whole circuit on. I think in this instance budget is a rcd spur or nowt unfortunately

 

[telectrix]

That may be an option though I'd need to do some additional tests before I put the whole circuit on. I think in this instance budget is a rcd spur or nowt unfortunately

all depends on the state of the RFC> a stand alone RCD will probably be kicking round in the back of your van (there's 6 in my van, various makes), dead money. all you need is an enclosure.

 

[pc1966]

One of the curious aspects of the whole RCD-FCU issue is no one has come forward to say why the don't conform for additional protection. Or indeed what the "supplementary protection" is that they do provide.

There was an IET Q&A that just repeated some weaselly statement about standards, but did not say anything helpful. Someone could easily have given details, e.g. if the FCU standard lacks some aspect so some models are OK and other marginal, etc. But nothing, Which makes me deeply suspicions that is the reason: they are not willing to call out any make/model as not good enough since it meets the letter of the 7288 standard but lacks something obvious/adequate that 61008 has.

So if it has to be a FCU then at least get one of the reputable brands that gives the break capacity, etc, in the data sheet.

 

[Pretty Mouth]

Beama's RCD handbook has a table on p22 listing various RC devices and their suitability for certain applications. The only significant difference listed between a FCURCD and an RCCB or RCBO seems to be that they are not suitable for 'fixed wiring protection'. Exactly what is meant by that I am unsure.

They are however listed as suitable for personal protection (additional protection of persons or livestock against direct contact), protection against electrical fire, socket outlets 20A or less, and portable appliances 20A or less.

https://www.beama.org.uk/static/uploaded/aa78bfa3-2fe0-4982-b74dbe1e7caad081.pdf

 

[pc1966]

Beama's RCD handbook has a table on p22 listing various RC devices and their suitability for certain applications.

That is quite a useful guide book!

The only significant difference listed between a FCURCD and an RCCB or RCBO seems to be that they are not suitable for 'fixed wiring protection'. Exactly what is meant by that I am unsure.

Exactly!

One obvious limit is the FCU-RCD is limited to the 13A fuse so it can't really be used for anything beyond the equivalent of a fused spur or lighting circuit. Of course, in many cases (like this thread) that is exactly what is desired and it would appear they are sufficient for that job.

After all, what really is the difference between fixed wiring (that meets this <= 13A current limit) and flexible cables like an extension lead in terms of necessary protection?

 

[westward10]

In my eyes the whole thing with rcd spurs/sockets is unclear maybe why they are not included in BS7671. I certainly wouldn't want to be explaining if the worst was to happen why I employed one as opposed to following the requirements of BS7671.

 

[Pretty Mouth]

That is quite a useful guide book!

Exactly!

One obvious limit is the FCU-RCD is limited to the 13A fuse so it can't really be used for anything beyond the equivalent of a fused spur or lighting circuit. Of course, in many cases (like this thread) that is exactly what is desired and it would appear they are sufficient for that job.

After all, what really is the difference between fixed wiring (that meets this <= 13A current limit) and flexible cables like an extension lead in terms of necessary protection?

I struggle to see why using FCURCDs for additional protection would be a problem for minor additions and alterations, and do use them occasionally where the CU is obsolete and RCBOs are not available.

I've just sent an email to greenbrook (powerbreaker FCURCDs) to see if they can shed any light. Will update if/when a reply comes

 

[Dartlec]

I struggle to see why using FCURCDs for additional protection would be a problem for minor additions and alterations, and do use them occasionally where the CU is obsolete and RCBOs are not available.

I've just sent an email to greenbrook (powerbreaker FCURCDs) to see if they can shed any light. Will update if/when a reply comes

Will be very interesting to see what they come back with.

If they don't meet the 7671 requirements for additional protection, then in a domestic setting I don't really see what their intended usage would be, apart from maybe to comply with manufacturers instructions on a fixed load that wouldn't require an RCD otherwise? Any property needing them for fault protection would generally not be solved with a single FCU, or even RCD sockets everywhere.

The manufacturers of them certainly push them to the domestic market as a way of adding 'protection', but maybe they are careful to never claim they can add 'required' protection.

I've used them on occasions on minor works where a single socket or light is being added and there is not a simple solution at the CU without a complete board change, which the job does not justify. They seem like they should be a perfect solution to that problem.

 

[Dartlec]

That has the screenshot I obviously saw, though also some conflicting advice from elsewhere ?‍

Though it seems there has been a new version of the standard BS 7288 standard (2019 previously 2016) that has more onerous requirements, but without access to the standards I have no idea if it's made them more or less suitable..

Anyone notice if they put them back in for the DPC for AMD 2?

I looked it up and they haven't added them back in it appears (not in 531.3.4.1 at least)

Having said that it doesn't mention older standards such as 4293 either - so is that station the position that adding a socket onto an older but functioning BS4293 board would automatically not be compliant with BS7671?

 

[loz2754]

No, but adding a new BS4293 RCD would be non compliant because BS4293 is an obsolete standard, whereas BS EN 7288 is current.
Maybe...

 

[Ampo]

Wow thanks for all the responses, its clear to me that this subject is far from clear. Its a shame as it's a really important thing for us to have a definitive answer on. There are situations such as mine where a straight forward job can become awkward if we can't use them. I used to think they were fine and have added towel rails and so on in the past using them. In this instance with a couple outside 3a spurs I really can't see why the regs wouldn't allow it, seems overkill. I think the the end result of these sort of grey areas is that I won't be able to do it and then a less "awkward expensive" spark will simply chuck in standard spurs and walk away.

 

[Lister1987]

Some additional court reporting from the Romford Recorder in this article, which also provides images of the DB to which this circuit had been connected and notable is the absence of additional protection. This work was undertaken in the early part of 2108, at which time AM3 was in force.

I believe there was an article in "Connections", the NICEIC magazine, that states that 7288 RCDs are considered acceptable as additional protection in the NICEIC's view. (Though it is as pointed out a deviation from BS7671 at the moment).

What that opinion is worth is up to the installer I guess - I did save a copy for reference so I'll see if I can find it...

Taken from an edition of Wiring Matters (https://electrical.------.org/bs-7671/faqs/qa-from-rcds-selection-types-and-testing-webinar/);

Are S-RCDs and FCU-RCDs (to BS 7288) recognised for additional protection in BS 7671?
RCDs to BS 7288 are not recognised for use as an RCD by BS 7671:2018. See Regulation Group 531.3.4.

Clause 1 of BS 7288:2016 states “SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”

Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit), nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

However, there is nothing to stop accessories containing SRCDs to BS 7288 being fitted in electrical installations complying with BS 7671, as they comply with the relevant standards, although as stated the RCDs within them cannot be recognised for the functions of fault protection or additional protection for the purses of BS 7671.

-

The key point is that SRCDs to 7288 lack the sufficient clearances found in 61008/61009 devices, this is the reason they can't be used for Additional Protection. I'll see if I can dig out the relevant clauses from BS7288

 

[Dartlec]

Taken from an edition of Wiring Matters (https://electrical.electriciansforu...m-rcds-selection-types-and-testing-webinar/);

Are S-RCDs and FCU-RCDs (to BS 7288) recognised for additional protection in BS 7671?
RCDs to BS 7288 are not recognised for use as an RCD by BS 7671:2018. See Regulation Group 531.3.4.

Clause 1 of BS 7288:2016 states “SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”

Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit), nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

However, there is nothing to stop accessories containing SRCDs to BS 7288 being fitted in electrical installations complying with BS 7671, as they comply with the relevant standards, although as stated the RCDs within them cannot be recognised for the functions of fault protection or additional protection for the purses of BS 7671.

-

The key point is that SRCDs to 7288 lack the sufficient clearances found in 61008/61009 devices, this is the reason they can't be used for Additional Protection. I'll see if I can dig out the relevant clauses from BS7288

Link doesn't work now it seems, but who was the answer from? Had anything changed since the other answer mentioned that states they are suitable RCD types for the purposes of additional protection? Or is this two different bodies coming to different conclusions?

But given this answer, where would one feasibly find any use for them then?

If suitable 30mA additional protection is available upstream, why would one use a FCU-RCD instead of a normal FCU, particularly when they all seem to be 30mA, so no selectivity available?

The standard was changed in 2019, so it would be interesting to see if anything improved or was altered in that, but us mere mortals can never get to see such precious resources of course.

But the fact that there is still a discussion about this without being able to get a clear definitive answer outside of Q&A in publications shows the failure of the 'system' to be clear or consistent.

 

[Pretty Mouth]

Taken from an edition of Wiring Matters (https://electrical.electriciansforu...m-rcds-selection-types-and-testing-webinar/);

Are S-RCDs and FCU-RCDs (to BS 7288) recognised for additional protection in BS 7671?
RCDs to BS 7288 are not recognised for use as an RCD by BS 7671:2018. See Regulation Group 531.3.4.

Clause 1 of BS 7288:2016 states “SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”

Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit), nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

However, there is nothing to stop accessories containing SRCDs to BS 7288 being fitted in electrical installations complying with BS 7671, as they comply with the relevant standards, although as stated the RCDs within them cannot be recognised for the functions of fault protection or additional protection for the purses of BS 7671.

-

The key point is that SRCDs to 7288 lack the sufficient clearances found in 61008/61009 devices, this is the reason they can't be used for Additional Protection. I'll see if I can dig out the relevant clauses from BS7288

I can't get that link to work, it may be that the forum automatically censored it - I'm sure I had a similar problem before. Googling some of a sentence from what you posted took me to the webpage:

https://electrical.------.org/bs-7671/faqs/qa-from-rcds-selection-types-and-testing-webinar/

EDIT: yeah, looks like the forum censored it.

EDIT #2: Google "Are S-RCDs and FCU-RCDs (to BS 7288) recognised for additional protection in BS 7671?" including the quotation marks, it should be the first result.

 

[Lister1987]

Link doesn't work now it seems, but who was the answer from? Had anything changed since the other answer mentioned that states they are suitable RCD types for the purposes of additional protection? Or is this two different bodies coming to different conclusions?

But given this answer, where would one feasibly find any use for them then?

If suitable 30mA additional protection is available upstream, why would one use a FCU-RCD instead of a normal FCU, particularly when they all seem to be 30mA, so no selectivity available?

The standard was changed in 2019, so it would be interesting to see if anything improved or was altered in that, but us mere mortals can never get to see such precious resources of course.

But the fact that there is still a discussion about this without being able to get a clear definitive answer outside of Q&A in publications shows the failure of the 'system' to be clear or consistent.

https://electrical.electriciansforums.org/bs-7671/faqs/qa-from-rcds-selection-types-and-testing-webinar

Should now work.

BSI website lists the 2016 as the latest, with the standard currently under review.

The answer is definitive and clear as it's on black and white in Clauses 0 & 1 of the product standard

 

[Dartlec]

I can't get that link to work, it may be that the forum automatically censored it - I'm sure I had a similar problem before. Googling some of a sentence from what you posted took me to the webpage:

https://electrical.electriciansforu...rom-rcds-selection-types-and-testing-webinar/

EDIT: yeah, looks like the forum censored it.

Seems like the forum is editing the link somehow - it should be linking to the IET, but googling finds it.

That seems to be saying that it does offer additional protection for persons, but not for fire - but is the requirement for additional protection on domestic lighting circuits, for example, not designed for protection against direct contact for persons (with the fire protection part of an RCD being a benefit rather than a requirement?)

The lack suitability of use for fault protection is fair enough - though the fuse in the FCU part might meet that in certain circuits, might it not? Not sure if that is part of the 7288 standard or not.

 

[Dartlec]

https://electrical.electriciansforums.org/bs-7671/faqs/qa-from-rcds-selection-types-and-testing-webinar

Should now work.

BSI website lists the 2016 as the latest, with the standard currently under review.

The answer is definitive and clear as it's on black and white in Clauses 0 & 1 of the product standard

It looks like the 2016 standard actually only came into force in November 2019 - and that the clauses you mention were added then perhaps.?

Some interesting discussion here - Electrical Blog - Electrical Advice | Free Electricians Advice Forum - https://electriciansforums.co.uk/discussions/viewtopic/1037/24702#forums-view-topic

If the link works. (Edit: external links seem to being mucked up at the moment... add communities PERIOD ------ PERIOD org in place of electriciansforums.co.uk and it will work....

EDIT 2: GRRRR - the spam filter seems to be preventing any external website links at all... or really doesn't like linking to IET communities!

Search for “Additional change agreed following April 2019 meeting to include reference to BS 7288 for SRCD and FCURCD in clauses 531.3.4.1 & 531.3.4.2”

Which discusses the confusion too - but also seems to have a quote from an IET page that no longer exists - that said:

“Additional change agreed following April 2019 meeting to include reference to BS 7288 for SRCD and FCURCD in clauses 531.3.4.1 & 531.3.4.2”

Which suggests that at one point they did think it was a mistake and would add it - that seems to be where the "Connections" answer was coming from.

The IETs link (which was from a webinar in Dec 2020 so more recent) seems clear - but outside of buying the actual standard, there doesn't seem to be a definitive statement in a published guide anywhere that states they cannot be used for the only scenario when anyone would actually buy one?

I'm betting that the manufacturers instructions for the currently on sale RCD-FCUs don't say that upstream additional protection must be in place?

 

[loz2754]

I just tried posting several links to different websites, but the forum borks them up by changing the domain name.

 

[Dartlec]

https://electrical.electriciansforu...rom-rcds-selection-types-and-testing-webinar/

Apparently the forum software does not allow linking to IET communities, however you try.... even putting it in with spaces and the word DOT in between (not as a link) changes it to electriciansforums.org domain....

 

[Pretty Mouth]

I take issue with that Q+A article. 3 different questions are asked on SRCDs and FCURCDs, and the exact same cut-and-paste reply is given to each, like it was written by a politician.


Clause 1 of BS 7288:2016 states ”“SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”″

Well, obviously an RCD socket isn't going to protect the circuit itself, upstream of the device.


Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit),

irrelevant, they weren't asked about fault protection.

nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

No RCD will, without having integral overcurrent protection, protect against short circuit. Again, irrelevant.

 

[pc1966]

From the IET's answers it seems they are chocolate fireguards as, to be complaint with the 18th, you need "additional protection" and once you have that what is the point of a RCD socket or FCU?

However, one interesting point is the standard stating:

...only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit)...

Now my reading of that is you could use them to supply outside sockets where electric shock is the key risk, provided the disconnection times are being met by means of an acceptably low Zs value. However, you could not use them to deal with a long cable and low static load where you meet the VD requirements but can't disconnect in under 0.4s on the OCPD.