To Earth or Not To Earth that is the question

[ban-all-sheds]

Should I earth the conduit

To cut to the chase:

No, as long as you use DI or insulated & sheathed cables.

 

[JohnW2]

Should I earth the conduit

To cut to the chase: No, as long as you use DI or insulated & sheathed cables.

I'm not sure that is a fair summary of the views expressed here - since there are clearly differences of opinion. In fact, AFAICS, of the electricians who have commented, one has said 'Yes' and the other a 'semi-yes' (by suggesting that the conduit is "by definition" an exposed-conductive-part).

I think that my view remains unchanged - that the regs probably do not require it (although I accept the argument that the conduit may be possibly be considered an exposed-c-p, which would then have to be earthed) - but, since it would do no harm (except in incredibly unlikely scenarios), and since it would mitigate some (very small) risks, one might as well earth the conduit, particularly if it's fairly easy to do so (and, of course, the more difficult it is to do, the less the advantage would there be in doing it).

Kind Regards, John

 

[lxboy]

The conduit should be earthed if you do not have RCD protection on that circuit.

Regards,

lxboy

 

[JohnW2]

The conduit should be earthed if you do not have RCD protection on that circuit.

I think we probably 'all' know that. The question is whether the conduit should be earthed if 'enclosed in earthed conduit' is not being used as the means of protection per 522.6.101 (e.g. if the cable is in a safe zone and RCD-protected). What is your view about that?

Kind Regards, John

 

[EFLImpudence]

The conduit should be earthed if you do not have RCD protection on that circuit.

That's not correct.

If, as I have suggested, the conduit may be considered an exposed conductive part and as such there is a danger of the conduit becoming live then it should be earthed.
You therefore, dependent on you decision, earth the conduit or not.

Whether the circuit is protected by an RCD is irrelevant as it would not (if the conduit were not earthed) disconnect the supply until someone touched the conduit.

Do you see why the threads 'go on' a bit?

 

[lxboy]

yes, potential saving their life .

Regards,

lxboy

 

[EFLImpudence]

But if you earth it, it will disconnect before they touch it - the purpose of earthing which cannot be omitted because an RCD is fitted.

 

[lxboy]

I think, that's what i said earth the conduit !

Kind regards,

lxboy

 

[EFLImpudence]

The conduit should be earthed if you do not have RCD protection on that circuit.

 

[JohnW2]

That's not correct. If, as I have suggested, the conduit may be considered an exposed conductive part and as such there is a danger of the conduit becoming live then it should be earthed.

Indeed. If one takes your view that it is an exposed-c-p, then it must be earthed, regardless of anything (including the presence/absence of RCD protection) - not, as Ixboy said (or, at least, implied), only if it is not RCD protected.

Whether the circuit is protected by an RCD is irrelevant as it would not (if the conduit were not earthed) disconnect the supply until someone touched the conduit.

I presume what Ixboy was getting at is that it does become relevant if one does not consdier the conduit as an exposed-c-p (so maybe he doesn't?). One then has (assuming depth <50mm) a choice of ways of satisfying 522.6.102/522.6.102 - either by having the cable 'in safe zones and RCD protected' or by having it 'enclosed in earthed conduit'. His very brief answer was presumably refering to the latter of these situations (since, without an RCD, the former could not be satisfied) - but it was certainly an 'incomplete' answer.

Kind Regards, John

 

[EFLImpudence]

One then has (assuming depth <50mm) a choice of ways of satisfying 522.6.102/522.6.102 - either by having the cable 'in safe zones and RCD protected' or by having it 'enclosed in earthed conduit'.

Yes, but that was not the question.

His very brief answer was presumably refering to the latter of these situations (since, without an RCD, the former could not be satisfied) - but it was certainly an 'incomplete' answer.

As the discussion has now changed from whether it is an exposed-c-p or not to whether RCD protection is required or not it would seem that, whatever the situation, it would be better if the conduit were earthed.

 

[JohnW2]

One then has (assuming depth <50mm) a choice of ways of satisfying 522.6.102/522.6.102 - either by having the cable 'in safe zones and RCD protected' or by having it 'enclosed in earthed conduit'.

Yes, but that was not the question.

Indeed it wasn't - but, as I said, the impression I got was that was probably the question that Ixboy was semi-answering. If one relying on 'enclosure in earthed conduit' as the means of satisfy the regs regarding cable protection (e.g. if the circuit is not RCD-protected and/or within safe zones, then it's hardly takes a rocket scientist to work outthatthe 'earthed conduit' has to be earthed

His very brief answer was presumably refering to the latter of these situations (since, without an RCD, the former could not be satisfied) - but it was certainly an 'incomplete' answer.

As the discussion has now changed from whether it is an exposed-c-p or not to whether RCD protection is required or not it would seem that, whatever the situation, it would be better if the conduit were earthed.

I don't think the discussion has changed - all those considerations are still on the table. To summarise as I see it:

1...If one is reliant on earthed conduit to satisfy 522.6, the the conduit obviously must be earthed
2...If one regards the conduit as being an exposed-c-p, then it must be earthed, regardless of anything else
3...IF neither (1) nor (2) apply, and one has satisfied 522.6 by having the cable in safe zones and RCD-protected, then there probably isn't a regulatory requirement to earth the conduit. However, since it looks as if (2) is always going to be a 'matter for debate', with varying opinions, it does indeed seem that the best/safest option is probably going to be to always earth the conduit - since very few people would argue with that (the theoretical 'risk' associated with having a bit of touchable earthed metal in the loft is probably vanishingly small).

That's how I now see it, anyway.

Kind Regards, John

 

[EFLImpudence]

Yes, agreed.

Just to say, though, that if the OP had not had to change the back-box (i.e. still connected to conduit) the conduit would be an exposed-c-p and would now be earthed anyway.

I suppose the conduit and back-box could still come into contact.

 

[AmateurFiFi]

Many thanks to all who've offered an opinion.

No photos available unfortunately.

The lighting circuit is RCD protected and the conduit is currently - and will remain with the T+E inside it - in a safe zone.

I will not be removing the conduit, as anyone who's had the "privelege" of working on masonary walls plastered with black mortar knows, as this will make black dust that will covering everything for ages.

 

[JohnW2]

Yes, agreed. Just to say, though, that if the OP had not had to change the back-box (i.e. still connected to conduit) the conduit would be an exposed-c-p and would now be earthed anyway.

Yes, I suppose so - but since you appear to regard it as an exposed-c-p whether or not it is connected to a back-box, that becomes a little moot!

Kind Regards, John