When was this last done?

Yes, that was the era to which I was referring. I've seen some lunacy of bonding from that era in bathrooms (and sometimes kitchens) - even with things like loo roll holders, (non-electrical) mirror frames and coat hooks being bonded!
If that was, indeed, the instruction in the regulations at the time, it does make one wonder about the competence of the authors.

Perhaps ignoring Table 52.3 is not such a crime - and thinking about everything else is advisable.
 
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If that was, indeed, the instruction in the regulations at the time, it does make one wonder about the competence of the authors.
Indeed, and one wonders how the electricians of those days thought about it. One would hope that most competent, intelligent and sensible electricians would have understood that a lot of it was plain crazy, but only did it "because the regulations said that they had to".

Kind Regards, John
 
12th or 13th edition, issued in 1950 and 1955 respectively. I have no idea what 12th/13th eds said about these things - maybe someone can recall!

I'm an old fart, but not that old!!

I'll try and find out.
 
when you consider that the lighting circuits didn't need a CPC back then (unless metal fittings), its OTT connecting to capping
 
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I presume it was done for personal protection (drills etc.) as is required now - rather than in case it became live.
 
the regs are not retrospective.
... Except when they are.

Nowhere does BS7671 state that they are "not retrospective". Views on safety change over time, and we certainly do not consider double pole fusing to be acceptable now (even though it was once permitted).
 
Nowhere does BS7671 state that they are "not retrospective". Views on safety change over time, and we certainly do not consider double pole fusing to be acceptable now (even though it was once permitted).
It doesn't say that in so many words, but there is a bit at the front that says that practices which were compliant with previous editions are not necessarily now regarded as unsafe.

The 'not retrospective' phrase we often hear usually really means that there is no requirement to bring existing installations up to current standards. That is essentially true - and, indeed, if it weren't true we would be facing an almost impossible situation. ... for a start, just think about all the 'inaccessible JBs' and buried cables there are out there!

Kind Regards, John
 
if it weren't true we would be facing an almost impossible situation. ... for a start, just think about all the 'inaccessible JBs' and buried cables there are out there!
And every single consumer unit/fuseboard installed in houses prior to January!
 
Clearly (some) of the place has been re-wired. As said, unusual the capping has bneen earthed. I notice it has been earthed with a bare conductor, which suggests original (1950s).


It may be the case then that the the bare earth wires may have been cut off, and no longer connected.

I would say earthed capping not in a safe zone is better than unearthed capping not in a safe zone.

I suppose the 'unprotected' side of the capping would be at least 50mm from the surface of the wall the other side.

It's not perfect, it's not right but it's not that bad.

As already mentioned, metal capping is easily drilled through, I unknowingly drilled through a dis-used concealed piece this week, very easily - had no idea until I removed the plaster.

Hard to date the installation without seeing inside the switches etc etc.
 
I would say earthed capping not in a safe zone is better than unearthed capping not in a safe zone. .... It's not perfect, it's not right but it's not that bad.
I would personally say that it's actually far 'better' than you are implying. 522.6.204(i) (in conjunction with 522.6.202) not only allows one to have a cable <50mm deep, not in a safe zone and not RCD protected if it is SWA, but also if it is pyro or 'ali tube' cable. Those latter two offer virtually no 'mechanical protection' to the conductors, so the regs are clearly 'happy' just on the basis of the live conductors being surrounded by an earthed conductor. Given that, as you say, the cable will usually be >50mm from the other side of the wall, one is only really concerned about penetration from one side, and if that side is covered with earthed metal capping, I would have though that the situation was at least as safe as (probably 'safer' than) with pyro or ali-tube cable.

Kind Regards, John
Edit: typo corrected
 
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I would personally say that it's actually far 'better' than you are implying. 522.6.204(i) (in conjunction with 522.6.202) not only allows one to have a cable <50mm deep, not in a safe zone and not RCD protected if it is SWA, but also if it is pyro or 'ali tube' cable. Those latter two offer virtually no 'mechanical protection' to the conductors, so the regs are clearly 'happy' just on the basis of the live conductors being surrounded by an earthed conductor. Given that, as you say, the cable will usually be <50mm from the other side of the wall, one is only really concerned about penetration from one side, and if that side is covered with earthed metal capping, I would have though that the situation was at least as safe as (probably 'safer' than) with pyro or ali-tube cable.

Kind Regards, John

I agree with everything you have said.

In the past, this forum has frequently dismissed the idea of using earthed metal capping where cables are not in a safe zone, but seems to me to satisfy most if not all of the requirements.

Is it acceptable?
 
Is it acceptable?
Not according to 522.6.204 which says the cable must incorporate its own metallic covering and quotes the BS numbers.

The capping may be alright for straight vertical runs up to a loft where it is visible, but
it cannot be completely buried as the earthing connection must be inspectable, and
it would be difficult to earth several pieces together for the typical cable runs.
 
I agree with everything you have said. In the past, this forum has frequently dismissed the idea of using earthed metal capping where cables are not in a safe zone, but seems to me to satisfy most if not all of the requirements. Is it acceptable?
As you will see (see EFLIs post), it can certainly be argued that it is 'not acceptable' (non-compliant) in terms of the explicit provisions of BS7671 (i.e. BS7671 does not explicitly say that this is acceptable). However, as I've said, I believe that it is at least as safe as some things which they do explicitly allow - so (if it could be done - see below) I think I would personally be happy to regard it as effectively compliant.

As EFLI has said, the practical problem is likely be in relation to earthing the capping in a manner which leaves those connections 'accessible' - albeit that's a requirement that has only crept into the regs fairly recently.

Kind Regards, John
 
Not according to 522.6.204 which says the cable must incorporate its own metallic covering and quotes the BS numbers.
Indeed - but, as I've said, some of those BS numbers refer to pyro and 'ali-tube' cable, neither of which offer even as much mechanical protection as does earthed steel capping. That's why I think the latter could/should be regarded as 'effectively compliant' (i.e. 'within the spirit of the regs' - something I'd never write if BAS were still around!).
The capping may be alright for straight vertical runs up to a loft where it is visible, but it cannot be completely buried as the earthing connection must be inspectable, and it would be difficult to earth several pieces together for the typical cable runs.
That's a good point, but one could theoretically overcome that problem by using one of the connection methods listed in 526.3(iv).

Kind Regards, John
 

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