recorded cpc size

[Engineer54]

Is that right eng, u should include a cpc if only for good working practice. What happens if the trunking continuity fails! We'll all be buggered if we scrimp on safety. Lol!!!

What would you know about ''Good Working Practice''?? lol!!

 

[Engineer54]

But you could say the same about cpc cables...

The benefit to using trunking as cpc is the very favourable R2 values you achieve, to add cable cpcs is just a waste of time, money and the world's resources - don't you care about the environment??

Also, all you will achieve, is filling up the containment systems with pointless CPC's, that can't come close to matching that of the containment system they are enclosed in!!

 

[pepparz]

Ive been to conduit and trunking jobs with no cpc that suffered with poor zs, if there had been a cpc this wouldn't have happened. So you do it your way eng and I'll do it mine, ok.

 

[pepparz]

Please stop loling ur messages it doesn't make the offensive ones less offending. Saying "what would you know" is childish.

 

[Hawkmoon]

Also, all you will achieve, is filling up the containment systems with pointless CPC's, that can't come close to matching that of the containment system they are enclosed in!!

Looking at the part of my post you highlighted, then your reply, I am guessing you perhaps 'speed read' it lol

 

[Badged01]

If you are still arguing that you can combine a copper CPC and a steel CPC to make up the required minimum CSA you are WRONG!! Which ever one you do choose, it must be capable of taking the full fault current on it's own, not as a combined entity. A fault will always choose the easiest route to earth, so it will be the copper conductor (with superior conductivity) that will take the hit in a combined copper/steel arrangement!!

Have to disagree with you there.

A fault current will split itself between the two with a ratio depending on resistance of the conductors. It will not all just flow down the one conductor. The steel has an equivalent copper x-sectional area (less than copper because its resistance to current flow is higher) so provided the two together meet the minimum x-sectional area required for the fault you satisfy the requirement.

That is my understanding of why reg 543 permits the mixed use of conductors.

 

[pepparz]

What would you know about ''Good Working Practice''?? lol!!

Nice edit.

 

[Engineer54]

Ive been to conduit and trunking jobs with no cpc that suffered with poor zs, if there had been a cpc this wouldn't have happened. So you do it your way eng and I'll do it mine, ok.

You would also swear that black was white if it suited your purpose!! ...lol!!

Oh i most certainly will, and actually am. There is not a single ''SEPARATE CPC'' in any of our metal containment systems throughout this project (which is around 85% overall, metal containment systems), and our Zs values will be far superior than anything you install with your superfluous CPC's...

 

[Engineer54]

Looking at the part of my post you highlighted, then your reply, I am guessing you perhaps 'speed read' it lol

I was agreeing with you Hawkmoon, i just added the containment fill factor

 

[Engineer54]

Have to disagree with you there.

A fault current will split itself between the two with a ratio depending on resistance of the conductors. It will not all just flow down the one conductor. The steel has an equivalent copper x-sectional area (less than copper because its resistance to current flow is higher) so provided the two together meet the minimum x-sectional area required for the fault you satisfy the requirement.

That is my understanding of why reg 543 permits the mixed use of conductors.

Think about your electrical training, and you'll see that it doesn't and can't work like that!!

 

[telectrix]

so, just to play devil, isf as you say, eng., that the containment acting as cpc is superior to a copper cable, then by that you mean that the containment has a lower R2 value. therefore the containment will carry a larger proportion of the fault current than the copper cable.

 

[gazj82]

I will add to this the words of my old mentor, "If you need to put a CPC in steel conduit, then you can't do steel conduit properly!"

 

[Engineer54]

Please stop loling ur messages it doesn't make the offensive ones less offending. Saying "what would you know" is childish.

I speak as i find i'm afraid!!

What can i say, you just keep making me laugh with your childish antics!! lol!!

 

[pepparz]

In the past I have had to rewire factory lighting because the continity of conduit has failed and there's been no cpc so had to rewire in swa 2 week job on a cherry picker.if there had been a internal cpc this wouldn't have happened.

 

[pepparz]

I will add to this the words of my old mentor, "If you need to put a CPC in steel conduit, then you can't do steel conduit properly!"

I agree to a point but go back in 25 years and check zs!