16th, 17th (and earlier?) - CPC sizing inconsistency..

benstoneham · 21 Feb 2008

Evening all.

Anyone come across this? I've just completed 2382-10 and it came up in a discussion...

Table 54.7 in 17th Edition (haven't got 16th to hand but I don't think it has changed) relating to 543.1.4 (cross section selection for CPC) show that where S (cross sector of line (urgh... that is never going to stick!) ) is <= 16mm, then the protective conductor (assuming same material) should the same as the line conductors.. i.e S

On that basis, 1.5, 2.5 etc T&E doesn't comply (2.5 + 1.5) and can't have done for any 16th edition installs..

Apologies if this has already been covered, just curious what people think..

Spark123 · 21 Feb 2008

543.1.1 allows the use of 543.1.3 (adiabatic) or 543.1.4 (the table you refer). As long as the reduced CPC satisfies the adiabatic then it is fine.

Dartlec · 21 Feb 2008

benstoneham said:
Evening all.

On that basis, 1.5, 2.5 etc T&E doesn't comply (2.5 + 1.5) and can't have done for any 16th edition installs..

Apologies if this has already been covered, just curious what people think..

I think the key words are that you can use that table where 'it is desired not to calculate the minimum'.

If you do the calculations I'm sure that T&E of all sizes work out fine, but since I trust someone else has already done the calucation I am happy to believe them at this time of night

I guess its reasonable that the tables work on quite wide margins, though that is perhaps wider than most...

Dartlec · 21 Feb 2008

damn...too slow

benstoneham · 21 Feb 2008

Right, yeah that would make sense. Too late tonight to get my calculator out... but I'll do it tomorrow and let you know!

Adam_151 · 22 Feb 2008

If you are using circuit breakers, you'll need the I²t let through energy data from the maker of the device to get sensible answers![/i]

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

16th, 17th (and earlier?) - CPC sizing inconsistency..

benstoneham

Spark123

Dartlec

Dartlec

benstoneham

Adam_151

DIYnot Local

Similar threads