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

In English then

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

so, pointless, unless you require to play the chance of failure game, and cascade 2  devices with poor failure rates, to have a system over all with a reasonable one.

So if say the change of wither the 1st RCD or the second failing to trip is perhaps 5%, the chance of both failing, so long as the failure mechanisms are independent is 0.25%.

I suspect this is not the intention.

As Mike has highlighted above, BS7288 has weird wording. BS7671 now refers to Additional Protection, though in the past editions these were supplementary protection [ against direct contact ]. The quote from BS7288 mentions supplementary -in general terms- while referring to Additional Protection in context  of BS7671. It is quite clear the use of Additional Protection in the quote from BS7288 is a mistake.


Someone , somewhere was concerned that, by implication, some persons fitting RCD sockets or RCD fcu,s assumed they were providing Additional protection to the fixed wiring upstream of the accessory rcd socket/ rcd fcu. That is obviously in BS7288, but most electricians will never read that document. So BS7671, crucially in the "selection and erection" section, removed BS7288 as "accepted devices". Seems to me more like forcing " a deemed to comply" on installers. But that Chapter [52] is for new work only. As others have pointed out BS4293 [ old style RCDs ] are also not included, but of course you would not be installing BS4293s for new work.


As for EICR, absolutely no coding for using an RCD socket or FCU for purposes of providing Additional Protection downstream of the Accessory . Exactly the same if you came across a BS4293 old style RCD. Under old PIR regime, the pendant could, say,  "code 4" [ not to current standards "but not necessarily unsafe" ] . However, if your inspection was for the more unusual purpose, such as regularisation or for a specific contractual reason, you would likely be more forceful to the deviation from the standard, but you could not deem it unsatisfactory for continued service and C2 it.


NB composed this before Sparkings post so a bit of duplication.

In English then

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

so, pointless, unless you require to play the chance of failure game, and cascade 2  devices with poor failure rates, to have a system over all with a reasonable one.

So if say the change of wither the 1st RCD or the second failing to trip is perhaps 5%, the chance of both failing, so long as the failure mechanisms are independent is 0.25%.

I suspect this is not the intention.

As Mike has highlighted above, BS7288 has weird wording. BS7671 now refers to Additional Protection, though in the past editions these were supplementary protection [ against direct contact ]. The quote from BS7288 mentions supplementary -in general terms- while referring to Additional Protection in context  of BS7671. It is quite clear the use of Additional Protection in the quote from BS7288 is a mistake.


Someone , somewhere was concerned that, by implication, some persons fitting RCD sockets or RCD fcu,s assumed they were providing Additional protection to the fixed wiring upstream of the accessory rcd socket/ rcd fcu. That is obviously in BS7288, but most electricians will never read that document. So BS7671, crucially in the "selection and erection" section, removed BS7288 as "accepted devices". Seems to me more like forcing " a deemed to comply" on installers. But that Chapter [52] is for new work only. As others have pointed out BS4293 [ old style RCDs ] are also not included, but of course you would not be installing BS4293s for new work.


As for EICR, absolutely no coding for using an RCD socket or FCU for purposes of providing Additional Protection downstream of the Accessory . Exactly the same if you came across a BS4293 old style RCD. Under old PIR regime, the pendant could, say,  "code 4" [ not to current standards "but not necessarily unsafe" ] . However, if your inspection was for the more unusual purpose, such as regularisation or for a specific contractual reason, you would likely be more forceful to the deviation from the standard, but you could not deem it unsatisfactory for continued service and C2 it.


NB composed this before Sparkings post so a bit of duplication.