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Topic Title: old wires to cooker switch
Topic Summary: borrowed cpc ok ?
Created On: 04 October 2012 10:30 PM
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 04 October 2012 10:30 PM
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ady1

Posts: 766
Joined: 19 April 2005

In a scenario where a cooker cable has no cpc. Can I borrow one from a near bye socket and does that still comply ......

Regards
Ady

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 04 October 2012 10:43 PM
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OldSparky

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I would think only on a temporary basis..

not good practice i my mind..
 05 October 2012 06:37 AM
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normcall

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I really must stop thinking.
I'm trying to think if I've ever seen a cooker circuit without a cpc. In fact, it used to be used as the path for the main earthing facility as the cooker and stop cock were usually in the kitchen, so a wire from the water pipe to cooker box (always metal) and then back to fusebox as always a circuit on it's own.
Nope, can't think I've ever seen it, so more investigation is called for on the rest of the installation.

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Norman
 05 October 2012 07:10 AM
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ady1

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Oh yes - the installation is cr%p - i've gone in to try and make it safe after a cowboy.
The cable is the old black rubber one, with no cpc. A single cloth covered in black was run alongside it, but the plonker cut it short thinking it was an old sup bond.
Ady

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 05 October 2012 09:57 AM
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Legh

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IMO, I think there's a point when patching up old electrical circuits causes more confusion and ambiguity and possible danger for other sparks and householders at a later date.
The only reason I can see why the client doesn't want a rewire would be lack of money.
So where you go from here?

Legh

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 05 October 2012 10:32 AM
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AJJewsbury

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Can I borrow one from a near bye socket and does that still comply ......

In principle you can have one c.p.c. shared by two or more circuits - there's a reg to specifically cover that (words to the effect that it should be sized to the worst case) - and would be common enough with steel conduit/trunking etc. But when you add in the requirements of good workmanship and maintainability (work on the socket circuit could endanger the cooker etc), it gets a lot trickier.

- Andy.
 05 October 2012 11:07 AM
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normcall

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I think Legh has hit it on the head.
It's a 'walk away before I get cross' situation. Safety is paramount as soon as you touch something!!

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Norman
 05 October 2012 11:08 AM
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GB

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I would suggest if it is in 2 core black rubber you may want to be renewing anyway (I know it may test out ok)
Also as pointed out borrowing a cpc is not good practice unless in a metal installation where the work on one circuit will "probably" not impair the safety on another.
 05 October 2012 12:23 PM
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daveparry1

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As it's a cooker circuit and the rubber cable is very old i'd run a new 6.00 mm t/e in. The alternative would be to run a new 4.00 mm earth back to the board but while you're doing that you might as well run a new t/e and be done with it,

Dave.
 05 October 2012 04:34 PM
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Rum1

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I would replace the whole cable - especially when i see rubber

Just wondering....is the socket on a ring (2 x cpc) or radial (1 x cpc). If the wiring is fairly old are they 1mm cpc? Just wondering as a cooker circuit would normally at least have a 2.5mm cpc and the cpc at the socket may not be surfice anyway!

But borrowing an earth for a cooker circuit i have to agree isn't very good practice....wouldn't want to put my name to it!!
 05 October 2012 10:04 PM
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antric2

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Evening all.
Black rubber cable has had its day.It might go on for years as long as it is not touched at all along any of the length.
It may test out fine for continued use but as well as raising and maintaining a standard within our industry,I think, we have a duty to educate our customers....and I dont mean to sound patronising...about things like this.No cpc and black rubber means new cable.It isnt a reg thing but a matter of covering your backside in this society of the blame culture.
I dont mess with black rubber cable anymore because you can open up a right can of worms(,it can really bite you unexpectedley can black rubber\VIR cable) down the line and from a cost point of view,surely the customer can be convinced of the advantage of a new cable.
Sorry,I will get off the soapbox now.
Regards
Antric
 05 October 2012 11:21 PM
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Legh

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Sorry,I will get off the soapbox now.



That's Ok, you let rip.........

Legh

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http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 06 October 2012 03:04 PM
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jsa986

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That job will cost you more in time trying to cover your ***** on that one, even if you are trying to make safe, if anything goes wrong you r last person to touch it. I would tell them its rewired properly, or get someone else.

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 08 October 2012 10:00 AM
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BigRed

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Do you really want to sign your name to it once you have finished, and be able to sleep at night?
 09 October 2012 06:54 PM
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ady1

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Thankyou for all the replies
Not my job - they fell out with the 'electrician' before me.
I rectified 13 faults then gave them a satisfactory report with notes codes etc.
I ended up pulling enough through the floor of the old cloth covered cpc single run alongside - i thought that was a safer option than borrowing a cpc from the socket ring.
Regards
Ady

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 10 October 2012 12:06 AM
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Martynduerden

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Originally posted by: GB

I would suggest if it is in 2 core black rubber you may want to be renewing anyway (I know it may test out ok)


That's a very good point, how old does an installation need to be before recommending a rewire, circuit tests OK the bits we can see are of but its 50 years old, is it OK for another 10, 20 ?

Tested an old place recently circa 1960 tested out fine looked old but OK not 17th by a mile, sockets on skirting etc etc client wanted to know if she should rewire as they were planning on staying there forever.


Where do you draw the line?

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 10 October 2012 06:40 AM
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normcall

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I understand it's this new fangled central heating causes most problems with rubber insulation - it dries out the oil, but it's OK as long as you don't touch it .
If they are intending staying there forever, then while they are still able to get out of bed, it might be a good idea to get in before it gets too hot as the heating goes up, the older you get.

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Norman
 10 October 2012 09:33 AM
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AJJewsbury

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I understand it's this new fangled central heating causes most problems with rubber insulation - it dries out the oil, but it's OK as long as you don't touch it .

That makes sense. My house (before it was mine) had been re-wired with PVC on all the habitable floors, but the basement lighting was still wired in rubber insulated & sheathed singles - which tested out fine. It is of course, pretty cool down there. It only got disconnected when the bits near the CU had to be moved to allow a rotted joist end to be dealt with and cracks started to appear in the sheath.
- Andy.
 10 October 2012 09:59 AM
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OMS

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That's a very good point, how old does an installation need to be before recommending a rewire, circuit tests OK the bits we can see are of but its 50 years old, is it OK for another 10, 20 ?


I guess it depends on what metric you examine it by Martyn - if it's just time based then it's difficult. If you include such things as cost of ownership and increased maintenance, the degradation of the initial investment at new, the speed at which it could be repaired (obsolescence), resilience, flexibility a nd potential future demands then it getsa bit easier - but it's a lot of effort to get to a point where you are saying "It needs a rewire" compared to some guy just sucking air over the teeth and pronouncing "It needs a rewire - i just know it does becaue I'm an electrician"

as an example, I've re used transformers that are 50 years old and have a maintenance history and binned old manual dependant switchgear because of operational risk and obsolesence - it easier to swap out a transformer within a few days than it it is to replace a faulted switchboard. I've re used submains that are MICC on some jobs and scrapped them on others. I've scraped 10 year old systems in XLPE because of change of use and kept 40 year old systems with conduit CPC's wired in capathene. all of those choices made based on robust assesment and a complete understanding of the clients aims and objectives.

At a domestic level, with little control over systems it's perhaps a little easier to decide but equally, the risks are low - in many cases, all we can do is defer the issue from a curent PIR to the next one - but different parties at different times will have different motivations - some of which will be financially driven if it's likely that there is a commercial advantage in reccomending a rewire - and that's true for both designers and installers - would I recommend in a condition report that was supported by a PIR that a rewire would be needed within 5 years - perhaps yes, - would I word it in such a way that would result in me getting a fee to design that rewire - who knows - would I recommend an installer to take it on, knowing that said installer might come back to me bcause of our previous relationship and employ me directly as his designer - again who knows - suffice to say that commercial pressures or incentive will influence the outcome - by how much is the unknown I guess

regards

OMS

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