Can we use the armour of an SWA as the CPC???

[Engineer54]

Here's a link to a site with relavant CSAs for both 70 degree and 90 degree armours:
steel wire armour as the earth conductor
The site has a number of downloads that may be usefull.

All the comments were great,every time my boss is sizeing swa for a job,he always asks can the armouring be used as cpc.I will show him these ta

The table's shown in this link is what you need to show your Boss!!

 

[micknew]

We use Amtech software and have never had the swa armour fail as a suitable earth conductor.
We specialise in domestic and heavy industrial installation work.

 

[Engineer54]

We use Amtech software and have never had the swa armour fail as a suitable earth conductor.
We specialise in domestic and heavy industrial installation work.

That would depend on size and core number, it would also depend if your program automatically undertakes adiabatic equations in it's calculations. But it's not always the case where the SWA will meet the cables requirements of being the CPC...

Where figures work out, that are right on the knuckle so to speak, you may have to look at the length of that cables run....

 

[Jeffmo65]

Hi folks very interesting post which provokes a lot of thought and reading / interpretation . I was once installing cabling for a large banking organisation for some UPS feeds , at that time we had our NICEIC assessment . Particularly he picked up on the fact that we had ran seperate CPC for the majority of the cabling installed , we stated that as a matter of belt and braces we installed these seperate CPC . At the time he informed us that anything less than 10mm2 (SWA) requires seperate CPC , so theoretically the seperate CPC installed by us was not required , but possible good practice .

 

[Engineer54]

Then the NICEIC inspector was clearly WRONG!! The Steel wire armour of the smaller SWA cables are more than adequate to be used as the circuits CPC. It's only after 95mm that you need to check for compliance!!

Things are a bit different if your intending to use the SWA for bonding purposes. As the SWA then needs to meet the copper equivalent of the required minimal bonding conductor size related to that installation...

 

[Jeffmo65]

As a respected member i will bow to your superior knowledge , as it happens our qualifying supervisor at the time then held the nic mans words to be good and all installs from then were done with compliance with his argument . i was not trying to say that this was wrong or wright , but just passing comment on my personal experience . As it happens i very rarely install a seperate CPC until as you say we get to the larger cables in which my AMTECH program works it all out quite nicely for me .

 

[Deleted member 26818]

Up untill this amendment, it was in actual fact a non-compliance to run a separate CPC with SWA.
They had to amend 521.5.2 (now 521.5.1), to allow it.

 

[Jeffmo65]

My appreciation for the quote of regs , however for at least the last 5 years on most of the large coporate installs i have been attached to the majority of SWA have had external seperate CPC's ran with them , so i assume not many people either do not read or understand the regs with or without new ammendments . not complaining just commenting

 

[Engineer54]

My appreciation for the quote of regs , however for at least the last 5 years on most of the large coporate installs i have been attached to the majority of SWA have had external seperate CPC's ran with them , so i assume not many people either do not read or understand the regs with or without new ammendments . not complaining just commenting

Don't doubt it, as it was the only way to provide a CPC for a SWA when the wire armouring couldn't comply as the CPC!! lol!!

But it just shows you how the NICEIC likes to make-up it's own regulations, and often getting things totally wrong in the process!! lol!!

 

[pactrol]

Hi Hawk81

yes I come across that quite a lot myself & whats the betting that they have used Bw glands instead of weatherproof cw type