Cross sectional area current capacity

[mbrooke]

That makes sense. Now my understanding is the factor is less restrictive for 1.5mm2 because smaller conductors can dissipate heat better? Or is it the other way around? Correct to think that heat dissipation of 2.08mm2 is in between 1.5mm2 and 2.5mm2?

Yes, I suppose that's got to be true to some extent, but there's hardly any difference between 1.35 and 1.38, so one might as well 'be conservative'! However, I also suspect that some of the small variation in the de-rating factors (from 1.39 for 1mm² {yes, fractionally higher than 1.5mm² and 2.5mm²} to 1.49 at 16mm²) may be as much to do with rounding as anything else.

Kind Regards, John

OK, doing more research I came across this, not sure if it helps though, the tables used for countries that use 2.08mm2 wire. But it has me confused. At 75*C, 2.08 is listed at 20amps. I take it the conductor insulation is rated higher?

http://www.encorewire.com/wp-content/uploads/wire-size-table-CU.png

http://i.stack.imgur.com/V56uL.png

And the old table 310.16 before it was changed to the above:

 

[JohnW2]

OK, doing more research I came across this, not sure if it helps though, the tables used for countries that use 2.08mm2 wire. But it has me confused. At 75*C, 2.08 is listed at 20amps. I take it the conductor insulation is rated higher?

I think you are probably looking for too much precision and consistency. It is widely believed/accepted that CCC tables are very conservative (i.e. have large 'safety margins' built in) - and since those margins are essentially arbitrary, it's hardly surprising that different countries/authorities come up with somewhat different figures. However, if you're thinking of using such cable in the UK, it seems reasonable to use interpolation/modelling based on the CCC Tables we work with in the UK - hence the figures I suggested. Is this just a hypothetical question, or do you plan to use such cable (and, if so, what for?)?

Kind Regards, John