Sagging Supply Cables

[JohnW2]

Either .... he or his employer have accepted that seals get broken left right and centre.

Possibly. As I implied, I'm not really clear as to why the neutral block is sealed, anyway. (would a neutral bypass across a 3-phase meter achieve anything? I would have suspected not)

or ... he didn't inspect the cutout and realise there is no separate earth block.

He did see it, but that may have been after the conversation to which I referred. Actually, it's not what I would call a 'cutout' - it's three separate fuse carriers (one for each phase) plus a Henley block for neutral

or ... he expects you to get someone else from the DNO to provide the connection

That was my point - he seemed to be saying that 'I' (my electrician) could do it without any DNO involvement.

What he was saying obviously makes engineering sense, so I suppose it was 'rules'/bureaucracy that I was thinking about. Silly though it sounds, I suppose it just 'felt wrong' to me for a consumer (consumer's electrician) to be connecting their installation's CPCs and bonding to an incoming neutral conductor, rather than to something (connected to that neutral!) suppleid by DNO and called 'earth'

Kind Regards, John.

 

[westie101]

Hmmm, dare I admit that occasionally the odd cutout has remained unsealed after I've inspected them!

 

[Lectrician]

If they are replacing the service cable they will pretty much treat it as a new service and replace the service head too. Providing a earthing facility is pretty much expected these days.

 

[JohnW2]

If they are replacing the service cable they will pretty much treat it as a new service and replace the service head too. Providing a earthing facility is pretty much expected these days.

Yes, I suspected that's probably what will happen if/when they replace the cable. However, the chap's comment about using the neutral feed as an earthing facility appeared to apply to the present, as well as the situation which will arise if/when I get a 'proper' service head.

One question about that presumed future occurred to me. If they do provide a new TN-C(-S) service head, will they insist on also installing one of those 'PME Warning' stickers/labels, even if I choose to ignore their 'earthing facility' and stick with my TT electrode (in which case the PME label would be untrue, in terms of the insallation, and hence misleading)?

Kind Regards, John.

 

[Lectrician]

Some DNO's fit stickers, some don't. Rare to see the stickers here except on older installs.

Weather they do or not, the sticker indicates there is PME at the service head, and not necessarily the installation itself.

 

[JohnW2]

Weather they do or not, the sticker indicates there is PME at the service head, and not necessarily the installation itself.

IIRC, the ones I've seen 'warn' that the installation is protected by protective multiple earthing and warn that tools/appliances should not be used outdoors without RCD protection. Are current/modern ones different from that?

Kind Regards, John.

 

[JohnW2]

I'm at a disadvantage here, because I'm not familiar with the various cables or what they are called. The cable which travels from the pole to the building here looks like four twisted black-insulated singles and it's been there for an awful lot longer than 5-6 years. I'll try to take a photo tomorrow.

Here a couple of photos. The near-horizontal (on photo) cable heading off to the right is my supply. Is this 'ABC' cable?

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• JohnW2
• 10 Aug 2011
• 1

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• JohnW2
• 10 Aug 2011
• 1

Kind Regards, John.

 

[westie101]

Yes that's ABC

 

[JohnW2]

Yes that's ABC

Thanks for confirming. What are the alternatives for the run between a pole and a consumer's property - just singles? Is straight con used? (bare conductors are presumably not acceptable!).

Kind Regards, John.

 

[westie101]

Concentric cables can be used but only over short didtances, or as just explained to me "it's finding a fixing on the property strong enough to hold it in the air"!
We can run it as mural wiring but it has a large bending radius as we use solid aluminium conductors.

ABC is actually good to run to a property but we wouldn't use it as murals owing to the single insulation and bending ssues, again, caused by solid aluminium.

To be honest we still use copper single core cables for 3 phase as they are far more flexible. Single phase tends to be single core concentrics.

 

[ban-all-sheds]

he looked at me a bit strangely when I asked if they used straight con for this sort of thing, saying that 3-core concentric would be 'rather a fat cable'.

And the OD of ABC with a sleeve over it is......?

 

[JohnW2]

Concentric cables .... We can run it as mural wiring but it has a large bending radius as we use solid aluminium conductors.
ABC is actually good to run to a property but we wouldn't use it as murals owing to the single insulation and bending ssues, again, caused by solid aluminium.
To be honest we still use copper single core cables for 3 phase as they are far more flexible. Single phase tends to be single core concentrics.

Intresting. The cable run of my supply along my (neighbour's) wall (some 15-20m in total length) involves going around an external corner of the property - so presumably would represent a bending radius problem for either concentric or ABC. It therefore sounds that it's most likley that they would replace the present four PVC singles with four PVC singles! - but, given that the present cable seems to be in reasonable condition, begs the question 'why?' (as I said the DNO 'fault man' who did the 'temporary clipping' yesterday seemed most concerned about the aesthetics).

Kind Regards, John.

 

[JohnW2]

he looked at me a bit strangely when I asked if they used straight con for this sort of thing, saying that 3-core concentric would be 'rather a fat cable'.

And the OD of ABC with a sleeve over it is......?

Quite - I would have suspected quite similar. Anyway, Westie seems to be saying that it would present a bending radius problem (exterior corner of buidling to be negotiated).

Kind Regards, John.

 

[ban-all-sheds]

Combine it with a change in height and it'll be fine.

 

[JohnW2]

Combine it with a change in height and it'll be fine.

I'm not sure I understand that, if you want the cable to remain pretty tight to the wall everywhere. One could do it with a big loop sticking out, but the squirrels and crows (and occasional cat) would probably use that as a swing! Anyway, I really don't know that I want this liquorice-like stuff on the wall!

Westie - what's the minimum bend radius for this (I guess 25mm²) ABC stuff (in a sheath)?

Kind Regards, John.