AMD 3 says "Product standards as listed in Appendix 1 for some protective devices, including RCCBs, RCBOs, circuit-breakers and AFDDs, require these devices to be marked to indicate if they are unidirectional e.g. “in” and “out” or “line” and “load” or arrows." - so no markings should indicate indicate that it's bi-directional.

   - Andy.

Or that it complies to an earlier version of the standard that pre-dates the need for such markings.

Not in this case, as it is very much a current device, but on older parts, beware...

Makers datasheet here does not mention anything.

That said I have always found them very helpful if you require a definitive statement

01543 455000 

info@electrium.co.uk

Mike.

Newfutile said:

Or should I just contact electrium 

Not a bad idea.

The data sheet for the nhxb20 is here. For the wrds is here. The installation instructions suggest that the RCD is bidirectional.

Could you not have done this for yourself?

As I understand it, Proteus mark their bidirectional devices with two arrows in opposite directions. Not a bad idea for implementing in the product standard.  

Proteus are doing a few good things recently, they are one of the few Makers who do a Type B RCD, I was looking for a F or B type this week, Hager dont seem to do them, well, some old webpages point to them, but not available in the UK.

On a similar subject, if we need to fit a type B, but the Maker doesnt make one, would it be ok to fit into an existing board, so long as busbar and front openings fit correctly?

Or, do we have to put in a separate, different make, CU to supply the one item that requires the Type B or F RCD? Making the intake cupboard look a real mess with an extra CU there, when there are plenty of spare ways in the existing CU.

From note 2 below 536.4.203. Sounds very onerous and fraught with possible kickback from future inspections. I think most sparks here would just fit it blissfully unaware of the consequences and not worry one bit about it. Likely where Ipf is well below device ratings, no real concern about safety exists. However, with +45 years of experience under my belt, I have learned not to be as cavalier as I might like to be. 

So for me its a separate enclosure. I take your point about the resulting piece-meal appearance.

Or that it complies to an earlier version of the standard that pre-dates the need for such markings.

Perhaps, but at the moment, the way things are (and the way BS 7671 is written), we can assume by default that older equipment is safe for bi-directional use. Manufacturer's data not always being available for obsolete devices (especially where the manufacturer may be ceased trading or had their name bought out by a Chinese supplier). Probably not a too unsafe assumption - since the old vanilla MCB or RCCB design is normally happy either way around.

   - Andy.

note 2 below 536.4.203. Sounds very onerous and fraught with possible kickback from future inspections.

True, but there is also the possibility that the future inspector is not aware of a carefully thought out  decision to adopt the responsibility.  In my occasional role as the design authority for making bits of kit, which among other things have other companies circuit breakers and so on inside them. Providing the evidence to declare these to be UKCA compliant, I often have the need to consider mix and match from different makers. almost always this can be guaranteed to be OK by design, especially by knowing that there is a suitable energy limiting fuse or similar upstream or from the construction of the enclosure.
note that many parts of the world that nominally follow the same rules as those from which BS7671 are derived, expect electricians to assemble the equivalent of the DB onsite and parts from more than one maker would not raise an eyebrow.

Mike.

AJJewsbury said:

Perhaps, but at the moment, the way things are (and the way BS 7671 is written), we can assume by default that older equipment is safe for bi-directional use.

Could you help us by explaining  how you came to that conclusion?

I was thinking of the wording of the NOTE to 530.3.201 - which seems to say to me that no marking of devices to the standards mentioned in Appendix 1 always implies bi-directional. e.g. Section 531.3.3 calls up "BS EN 61008 series" and appendix 1 lists "BS EN 61008" without any date qualification - which I think could be read as the NOTE applies to any version of BS EN 61008 - even pre 2017 ones.

I suppose you're going to point out that the more specific standard references in Appendix 1 are all date stamped though (e.g. BS EN 60898-1:2012+A12:2017) -  and so the NOTE could be read as applying on to that version ... so maybe there's some ambiguity there...

   - Andy.