IET announces new amendment to BS 7671 (IET Wiring Regulations)

This thread seems to be drifting towards the old argument as to whether BS 7671 is retrospective or not.


The statutory obligation is to be found in Part P of Schedule 1 to the Building Regulations 2010:


"P1. Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury."


The Approved Document gives guidance:


"1.1 Electrical installations should be designed and installed in accordance with BS 7671:2008 incorporating Amendment No 1:2011." It might have been better to have said "... in accordance with the current edition of BS 7671."


My interpretation of "reasonable provision" is that new circuits should comply with the current edition of BS 7671; but an electrician is entitled to use professional judgement when altering or adding to an existing circuit. The use of a BS 7288 device may be, in my opinion, reasonable.

It would also be a bit daft to say that a double pole FCURCD with its removable fuse cannot be used as a isolator, but a single pole RCBO upfront of the circuit can or for that matter a cooker control unit switch without a removable fuse or the facility to lock it off can.


BS7671 defines isolation as:

”Function intended to make dead for reasons of safety all or a discrete section of the electrical installation by separating the electrical installation, or a section thereof, from every source of electrical energy.


Section 537 Isolation and switching starts with:

537.1  General 

This section provides requirements for:

(I) non-automatic local and remote isolation and switching measures for the prevention or removal of dangers associated with electrical installations or electrically-powered equipment and machines, and

(ii) functional switching and control.


Non-automatic local isolation surely means that you can turn the isolator off by hand and/ or pull the fuse out of it.


Table 537.4 then gives guidance on the selection of isolation devices which includes fuses, which obviously have to be removed by hand and are single pole.


Andy Betteridge 

Jack, (our retiree) is not happy. It started when his twin rcd socket in his workshop was condemned by an EICR to the effect of = C2 potentially dangerous. Jack had bought and installed his socket around 3/4 years ago and as far as he was concerned it was from a reputable shop,and met the regulations at the time. It wasn't his place to wade through endless British Standards and guide books, and fitting was not rocket science. He got an electrician friend to confirm the trip time. All was well. Now every time the trip goes he has to take a brisk walk to the meter cupboard in the house. However, on the internet one evening he decided to do some digging. He found a piece in a publication "Wiring Matters" from 2015 that covered his type of trip sockets in detail. To his disbelief he found the paragraph, "there is no advantage to have two RCDs in series in his situation". Funny he thought, this was the header of Lisa Miles new topic from the new Wiring Matters, "new amendment to BS 7671" which says these devices now must have an upstream device as well. "These people don't know what they are talking" about he thought.


Jack has now reinstalled his SCRD in the workshop (and removed the RCD from the house)


Regards, UKPN

And to be honest, in "Jack's" shoes I'd do the same. BS7671 is not law and is not always the best solution.

John Peckham:

I think you are missing the point.  The product standard ( BS 7288) says they are not suitable for providing Additional protection. They were removed from BS 7671 deliberately for this reason. They do not provide isolation as they do not meet the minimum contact clearance. BS 4293 was removed because because it was an obsolete standard just like BS 1361 fuses.


Are you saying that you disagree with the product standard? 

No, I’m disagreeing with that interpretation.


I don’t have access to the full BS8277:2016 and don’t feel inclined to pay the price to view the full document.


However if you Go to the BSI website  you will find a link that allows you to read the first nine pages as a preview, click this link and go to the ninth page, there you will find the introduction and scope, now bear in mind that we cannot see the next page, do we don’t know from this is we are reading the whole of the section on the scope or not.


So look at some points it makes:

• A RCD protected socket does not need an isolation function, because you can pull the appliance plug out.

• Residual current devices covered by this standard are intended for additional protection in case of direct contact only.

• SRCDs are only intended to provide supplementary protection downstream of the SRCD.

• SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.

• SRCDs are neither intended to provide an isolation function nor intended to be used in IT systems.

• Note4 For SRCDs intended to provide an isolation function or fault protection or to be used in IT systems, BS EN 61008-1 or BS EN 61009-1 should be used, as applicable, in conjunction with the requirements of BS 1363-2 for socket-outlets.

So it does not actually say that they are not suitable for providing additional protection, but it indicates there are limitations to the protection afforded by them 


Having said that we need to understand that the additional protective provisions of an installation are RCDs and supplementary equipotential bonding. So as I keep trying to tell the plumbers, the requirements for supplementary bonding has not been removed from the Wiring Regulations. Installing a RCD to protect an appliance in a special location is insufficient if any supplementary bonding that is required is not installed.


These RCD devices only offer protection downstream of them, they have to be supplied by an adequately protected electrical circuit and any bonding that is required has to be installed.


Also neither The Electricity at Work Act or BS7671 requires an isolator to be lockable if it is under the control of the person working on the electrical installation, that is why the cooker switch within two metres of the cooker is okay despite not having the means to lock it off.

so neither the sockets or the connection units need to be lockable, so long as the person working on the appliance can take control of the job site and be sure the supply won’t be unexpectedly reconnected by someone else.


Andy B.

Thanks for the link to BSi.  The intro is revealing. Nothing has really changed; just perception due to the use of the word "supplementary". The standard does not state they are not suitable for Additional Protection, only along the lines of "supplementary" protection downstream is afforded [only]. That can be "supplementary protection" to fault or basic protection [ in-direct/direct in old money ]. The word Additional is not used as that is sub divided into two parts, the second including the sometime protection of buried cables . It is highlighting the limit of an accessory at the boundary of the fixed wiring. So in respect of AP, this is "direct contact" only as opposed to cables buried in walls. The design of the devices only has to meet the limited cable lengths that would be experienced at what is the extremity of the fixed wiring. It is not really anything new in the case of socket outlet RCDs; perhaps for RCD FCU it is more of a "problem" [?] if the spur "protects" a large length of downstream buried wiring .

SRCDS and SRCDs are intended for additional protection in case of direct contact, therefore they not intended for use when the Zs is to high to blow a fuse in the plug or connection unit, at the point they are connected into the main installation, for example in a TT installation.


A TT installation has to have an upfront RCD, so you cannot install a SRCD in a TT installation where the circuit it is connected to lacks RCD protection, but there could be a 100 mA RCD upfront of the 30 mA RCD.


Andy Betteridge

Where, if anywhere, in the Wiring Regulations or its Guidance Notes does it say that isolators have to have 3 mm contact separation when open?


I have heard this so many times, but cannot find where the requirement is stipulated.


Andy Betteridge

Here is a previous SRCD discussion from 2013:

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=51151