Discuss Testing SWA in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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i guess it's each to their own, but i don't think i'd be running SWA without a dedicated CPC, just what i was taught i guess
 
The electricity board relay totally on the armour in a TN-S system and TN-C-S sysyem. Regs say its fine so really cant see the problem with using the armour as the sole means of earthing.
 
ive seen allot of sparkys write (sheath) where you would normally write the size.makes sense to me as the armouring is a sheath.
 
HI,
The nic have a guide for this within one of their books.I had the same problem recently on a periodic test.The flats were built early 1980s and 2 core swa was used.It turns out that 16mm 2 core swa is equal to a 10 mm earth on the armour.I agree we would not rely on this now but my loop readings were fine so could not fault it.I also contacted the manufactors of the swa who confirmed the same.
 
NO NO NO - i believe you are very wrong there!

the armouring is not designed to be relied on as an earth connection!

the armourings reason for being there is to offer mechanical protection, end of - the earth connection is a benefit. the armourings are there to try and protect the cable from being cut through, which is why you use ARMOURED cable! armour is armour, earth is earth

i'm not saying it can't be used, it is (i believe) good practice to ensure if there is no core to be used as an earth then a seperate earth will be run. the csa of the armourings meets the requirements of the regulations (unless you start using single cores or two core SWA with conductor CSA's of greater than 120mm)

whilst it may be adequate on installation, with 5 years of degredation (depending on the environment) it could easily break down/rust at the glands or any breaks or water ingress into the pvc sheath.

if it's possible i'd always run a seperate earth, and it is in most circumstances i think reasonable to do so

I'm a bit confused
Two different views in two posts, So do you always run a separate CPC or do you sometimes rely on the armour even though you appear so against it
 
The selection and erection guidance note (don't have it here so can't remember specifics) tabulates most pvc and xlpe armour sizes and also states if the armour is adequate for use as the cpc without a parallel cable.;)
As far as I'm concerned if the CPC is run as a core within the cable I'll bond one end of the cable with a bolt and banjo, if the armour is to be used I'll banjo it and flylead it BOTH ENDS with a cable of a suitable size for a cpc so for the sake of argument 6mm/2.5 is standard T&E then a 2.5 single will be adequate as a flylead for a 6mm SWA.
 
Back to the original question....

There are tables in guidance note 1 which will tell you which cables can be used, pages 171 to 173, tables D9, D10A and D10B.

Therefore, would these tables be put in a guidance note if this was not an acceptable practice?
 

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