Imperial Cable

[mikep]

Was looking at the imperial T&E Cable rating chart I downloaded form here, if you have 7/029 which equates to 3mm & 3/029 on the cpc what is the actual mcb that should be used as the chart reads 31amps rating for the 7/029, now we all now you cannot get one of these.

The cpc is 3/029 which works out to 1.3mm, This could be the fly in the ointment depending on the Zs I suppose.

Do you down rate the ring to 20amp!

Answers on a postcard !!

Mike.

 

[ianmacd]

2.5mm T&E can only handle 27A Method C but that is still used for rings with 32A mcb's (with certain restrictions) so why would that be a problem? If it was a radial then yes, 20A it. If there are spurs off of spurs then 20A it but if its a proper ring with a single spur per accessory then 32A should be fine.

PSdidn't have a postcard

 

[PC Electrics]

Standard sizes of MCBs are 6, 10, 16, 20, 25, 32, 40, 50 & 63. Not many manufacturers make a 25A though.

Not really sure I understand what your getting at, perhaps you've missunderstood the cable rating system or design requirements.

7/029 has a rating of 31A, thus can be used in a 32A ring or 20A radial or 25A radial. A 32A ring requires a cable with a minimum rating of 20A.

The 3/029 cpc (=1.3mm) when used as the cpc, meets the requirements of the adiabatic equation for MCBs up to 40A. So a 7/036 cable with a 3/029 cpc can be used on a 40A MCB. I included this information on the chart because I do not know what the standard conductor vs cpc size combinations were for imperial cable, thus you can check suitability for any size combination..

 

[mikep]

I was having a funny thick turn when I posted that thread, yes did not think to double the 31amp capacity for a ring (brain stopped), As I said could not understand it as it was equal to 3mm, but needed to know if the cpc was ok being 1.3mm for this circuit and I was unsure of the chart.

Thought I should ask the question to get it straight in my mind.

I think it may be one of those days, probably end up being one of those weeks.

All clear now.

Thanks all, (especially PC Electrics) Mike headbang

 

[PC Electrics]

Hey, we all get a bit of 'brain fade' occassionally. When we work on our own we have no-one to 'bounce' it off, so that's where this forum comes in handy.

You're welcome.

 

[mikep]

That is so true, a differant approach sometimes can solve a problem instantly !!

Sometimes I'm not clever enough even to be stupid!!

Mike.

 

[fletchflash]

Can I have a link to the chart please? Does it have current carrying capacities for all sizes of imperial?

ive been looking for one for a while

cheers

 

[Evans Electric]

Just treat it as 2.5 T/E .

7/.029 was wonderful to work with 'cos it was stranded , instead of this metric carp they inflicted upon us.

Grumpy old Deke

 

[PC Electrics]

There ya go Flash:

http://www.talk.electricianforum.co.uk/downloads.php?do=file&id=63

 

[mikep]

Funny you say that, you forget how easy it is to pull, as I was re-routing about 1.5metres the other day, it was so enjoyable compared to T&E !!

Mike.