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I do realise that each cable is carrying 100A.

In example 1 they are running through a cable ( 2 cables in parallel) having a resisance of 0.025 ohms.
In example 2 they are running through a cable ( 2 cables, 2 circuits) having a resisance of 0.05 ohms.

Therefore the head created by example 1 is going to be lower that the heat created by example 2.
 
I get it...

You are winding me up!

This can be the only explanation lol


If not, reread post 58 - the answers are there - the penny may drop
 
What i'm saying is, that you don't apply a grouping factor to a single circuit, end of!! Can't get a much simpler explanation than that. For those that still think you DO, then explain to me why you don't apply the same requirement to RFC's run in containment, or a Trefoil run, (3 or 4 single cables grouped/bunched together) three phase supply circuit, which will often be supplying unbalanced end loads??


Jesus, this is harder than pulling teeth!!
 
Two cables, fully loaded and run together regardless of whether they are 1 or 2 circuits are going to be influential to each other regarding heat dissipation (that's what I meant when I said the difference is just terminology).

The fact that it is a parallel single circuit cannot, in itself, make the cables run any cooler - but that is what you seem to be saying.

I'm not saying that at all!!

No ''competent'' engineer or electrician, would ever design a circuit of any description which will run at, or that close to the cable(s) current rating. Now if you're going to play around with those sort of nonsensical scenarios, we really are just wasting our time here....
 
What i'm saying is, that you don't apply a grouping factor to a single circuit, end of!! Can't get a much simpler explanation than that. For those that still think you DO, then explain to me why you don't apply the same requirement to RFC's run in containment, or a Trefoil run, (3 or 4 single cables grouped/bunched together) three phase supply circuit, which will often be supplying unbalanced end loads??


Jesus, this is harder than pulling teeth!!

This is allowed for in current carrying capacities in BS7671 (3 phase cables of given size always lower value than twin)

...and the RFC issue is probably a compromise because, lets face it, the cables are hugely underloaded (2 x 26A = 52A capacity on a 32A breaker?)
 
I'm not saying that at all!!

No ''competent'' engineer or electrician, would ever design a circuit of any description which will run at, or that close to the cable(s) current rating. Now if you're going to play around with those sort of nonsensical scenarios, we really are just wasting our time here....

If you read my post after the one you are referring to you will note I acknowledged that I may have misinterpreted you - the parallel issue was largely from spoon and rockingit
 
This is allowed for in current carrying capacities in BS7671 (3 phase cables of given size always lower value than twin)

...and the RFC issue is probably a compromise because, lets face it, the cables are hugely underloaded (2 x 26A = 52A capacity on a 32A breaker?)

Which is exactly the same as i stated earlier, CCC capacities will be determined by the installation method used along with any other applicable correction factors, and is all that is required for any Single separated circuit!! So what's the difference then??

As far as the RFC goes, Not if we apply your previous perameters, eg runing the RFC at full load!!

So in other words you don't have an answer do you??
 
Which is exactly the same as i stated earlier, CCC capacities will be determined by the installation method used along with any other applicable correction factors, and is all that is required for any Single separated circuit!! So what's the difference then??

As far as the RFC goes, Not if we apply your previous perameters, eg runing the RFC at full load!!

So in other words you don't have an answer do you??


You see in my opinion your modified parallel circuit is not a situation allowed for in predetermined ccc, you have 2 cables, not one - this setup is not covered (imo) by the 'grouping factor only separate circuits' point in the regs.
With regard to full load of the cables, you won't even know what that is unless you apply relevant factors - imo this modified circuit should include at least a consideration toward heat dissipation.

I have only mentioned high loading of the cables as we are trying to install as small a cable as poss to carry the 100A (half the parallel demand)

My issue mainly has been that some are believing that heat in the cables will somehow be diminished because they are wired in a parallel formation (that's what I am arguing in post 58)
 
I answered your points, don't see where your frustration is...

you have chosen to 'interpret' the regs to suit your modified circuit, I have explained why I don't agree...

like I said we should agree to disagree on this :)


Eh, Where are you getting this ''Modified Circuit'' from?? Parallel supply circuits are, ...always have been and will continue to be a Standard/Normal circuit wiring method!!!!... Nothing ''modified'' about them... I'm Not interpreting the reg's to suit myself either, YOU DON'T APPLY A GROUPING FACTOR TO A SINGLE CIRCUIT!! ..End OF, it's bloody nonsense!!!
 
Eh, Where are you getting this ''Modified Circuit'' from?? Parallel supply circuits are, ...always have been and will continue to be a Standard/Normal circuit wiring method!!!!... Nothing ''modified'' about them... I'm Not interpreting the reg's to suit myself either, YOU DON'T APPLY A GROUPING FACTOR TO A SINGLE CIRCUIT!! ..End OF, it's bloody nonsense!!!


What if you had 10 cables, parallel circ as you describe, all tightly grouped and carrying 20A each, would you consider a grouping issue then? Oh but then it's only one circuit!

I can leave my extension lead fully wound with my 3 bar fire plugged in - its only one circuit!


Seriously Eng54, we are NEVER going to agree on this because we each believe we are right...End OF, to continue is bloody nonsense!!!
 
What if you had 10 cables, parallel circ as you describe, all tightly grouped and carrying 20A each, would you consider a grouping issue then? Oh but then it's only one circuit!

I can leave my extension lead fully wound with my 3 bar fire plugged in - its only one circuit!


Seriously Eng54, we are NEVER going to agree on this because we each believe we are right...End OF, to continue is bloody nonsense!!!

That circuit was a supply off a distribution transformer to a Switchboard, they carried a damn sight more than 20A a cable too, ....and NO, a grouping factor was NOT applied!!

Dear oh dear, perhaps you had better ask yourself ''WHY'' a roll of extension flex heats up under load, certainly has nothing to do with what is being discussed here??

To be honest, you had better stick to single cable supply circuits, just god help you if that works out to be a 1000mm, cause trying to multi parallel, and adding in a grouping factor, you're going to end up with in excess of 1000mm!!

Good idea, NO, you'll never convince me that a single parallel supply circuit needs a grouping factor applied!! lol!!
 
That circuit was a supply off a distribution transformer to a Switchboard, they carried a damn sight more than 20A a cable too, ....and NO, a grouping factor was NOT applied!!

Dear oh dear, perhaps you had better ask yourself ''WHY'' a roll of extension flex heats up under load, certainly has nothing to do with what is being discussed here??

To be honest, you had better stick to single cable supply circuits, just god help you if that works out to be a 1000mm, cause trying to multi parallel, and adding in a grouping factor, you're going to end up with in excess of 1000mm!!

Good idea, NO, you'll never convince me that a single parallel supply circuit needs a grouping factor applied!! lol!!


Eh? - I just made that up to explain my point - not real

Ahh - I see we are now dropping to the more 'personal' level - I am not an idiot just because I disagree with you Eng54

There will be no more input from me on this.
 
Eh? - I just made that up to explain my point - not real

Ahh - I see we are now dropping to the more 'personal' level - I am not an idiot just because I disagree with you Eng54

There will be no more input from me on this.

To be honest, that's more to do with frustration, than being personal!!
 

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