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

I read that discussion from the old forum again and looked up the same regs the the 18th.


The implication is that on a farm you have to add the requirements of the special location regs to the general regs, so by stating an additional requirement for farms that indicates it is not a general requirement, so if farms have to have RCDs in circuit rather than RCD protected sockets as an additional requirement, it’s not an general requirement.


That is one for the wordsmiths to hammer out.


Andy Betteridge 

And it says the new version meets the Wiring Regulations, but I am far from certain as to what that means.

Okay.


So the SRCDs and FCURCD devices are manufactured to two British Standards, including that one.


Quote:

”The Timeguard range of RCDs provides protection against fire hazard and rapid double pole disconnection from electric shock for the appliance and cable connected to it. They comply fully with BS7288 and BS1363.”

If you look at the installation instructions for the old Timeguard FCURCD it says BS 1363-4 on it next to BS 7288


Which brings me back to the point I have reiterated several times, when assessing the suitability of the device you have to compare it against both British Standards and although BS7288 says it isn’t an isolator, BS1363-4 does say it can be used as an isolator.

But it is stated the new version is to BS1363-2 and I don’t know if that makes a difference?


So surely the requirement that an device that provides additional protection can be used as an isolator is fulfilled. I can’t actually remember which reg that is now and can’t see a bookmark for it.


Andy Betteridge

Here is a previous SRCD discussion from 2013:

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

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

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

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 .

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.