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

[Chr!s]

Is the swa a ferromagnetic enclosure?, aren't the spacings in the armour sufficient to break down circulating currents.

 

[Deleted member 26818]

Yes the SWA is a ferromagnetic enclosure. However there is apparently going to be an exception to the requirement for CPCs to be within the ferromagnetic enclosure for SWA in the first ammendment.

 

[Chr!s]

Yes the SWA is a ferromagnetic enclosure. However there is apparently going to be an exception to the requirement for CPCs to be within the ferromagnetic enclosure for SWA in the first ammendment.

So i believe, think its due to test showing armoring spacing breaking down circulating currents

 

[Deleted member 26818]

There is a report about from the ERA, produced for the ECA, I believe it's entitled 'ECA appendix 16' or similar.
This has information on the use of a separate CPC with SWA.

 

[xXDeltaXx]

Just a little addition in relation to a previous point...
People coming from a 'fast track' scheme may not have covered this in enough detail to know for certain if the SWA armour is suitable for an installation - I know that I am / was unsure - This thread has helped me

I'm not quite sure on the point about loosing business to someone fresh (inexperienced) into the industry...
I will just state that the reason I'm here and looking for this info is because my company (not electrical) has an old boiler installation (late 80s) which I believe to be unsafe / questionable methods have been used on installations / modifications. The company has had electicians into and around the area before and no-one has commented on the installation - thus it will remain unchecked until it goes wrong. By carrying out calculations and checks, I hope to be able to get things rectified...
This kind of topic may end up generating jobs for the more experienced electrician rather than taking them away.

 

[andyemms]

Well I have found all this a very interesting read... I for one would choose to use both the armouring and an extra core as a CPC.

I'm not quite sure on the point about loosing business to someone fresh (inexperienced) into the industry...
I will just state that the reason I'm here and looking for this info is because my company (not electrical) has an old boiler installation (late 80s) which I believe to be unsafe / questionable methods have been used on installations / modifications. The company has had electicians into and around the area before and no-one has commented on the installation - thus it will remain unchecked until it goes wrong. By carrying out calculations and checks, I hope to be able to get things rectified...
This kind of topic may end up generating jobs for the more experienced electrician rather than taking them away.

I think it is important to remember that this forum attracts people from everyday walks of life. There are some very knowledgeable and experienced people on here, there are some very knowledgeable but inexperienced people on here and there are people that have very little knowledge or experience. But we are all here for a reason, either to share our knowledge, or to gain knowledge.

YEEE HAAAAAA!

 

[Dave_]

Nice to see this thread is still going!

I always run a run a seperate cpc (boss says so!) although its very easy to prove its not a necessity (adiabatic). good practice. He has 30 years more experience than me. I just do as i am told.............................

 

[biguner]

Doesnt it depend on the csa and length of run as to whether or not it needs additional cpc?

 

[IQ Electrical]

Doesnt it depend on the csa and length of run as to whether or not it needs additional cpc?

Your answer is in post 1

 

[tom1400l]

yes, its supposed to be earthed (c.p.c) anyway, try and get terminate it so that you can get the lowest resistance you can get

 

[i=p/u]

when reading the table lenny posted , doest st mean strands and cu as ccc

 

[tony mc]

St is the actual steel armour csa

Cu is the copper equivalent csa

 

[i=p/u]

so 1.5mm phase conductor in swa has 15mm csa swa as cpc and 6.65 equivelent in copper.. if im on right track

 

[tony mc]

Yes you are and thats for 2 core swa.

 

[i=p/u]

good man, wont have to ask again, stuck

 

[mattd888]

I have a similar table that the niceic sent me. Another point is that although the armouring is suitable for the circuits cpc it would be important to remember that it my not satisfy the requirements for bonding of water pipes etc if the armoured was a sub feed. Rotting of the armouring can be an issue but that is why a periodic inspection is/should be carried out to catch such issues before it completly breaks down.

 

[BARK982]

The armour of swa should always be connected to earth and that's why you don't have to rcd protect a swa because if you damage it you will hit an earth before a live conductor, thats why you don't see a lot of two core swa about because people stopped buying it and just using the old yellow or new black as the earth. But the cross sectional area of the swa is larger than the earth conductor inside the cable, but why not connect both.

 

[johnny999]

This is the reason why we were taught at collage not to use it!!

 

[malcolmsanford]

This is the reason why we were taught at collage not to use it!!

You have been taught in a college never to consider using the armoured of a SWA as the CPC?

 

[Engineer54]

You have been taught in a college never to consider using the armoured of a SWA as the CPC?

The mind just has to boggle at some of these so called competent to teach Electrical lecturers these day's.