IEC 60364 Table 48A

mapj1:

The thing about the Pace consulting notes and the you tube videos is that they relate to 110V land, where installation practices are very different. 

I do not think you could set fire to a UK extension lead in a cardboard sandwich  and expect it to remain live and sizzling for very long at all, certainly only a few seconds, not minutes.

230V land regulations actually require us to verify Zs, and the L-N equivalent when we test PSSC, and that coupled with the maximum voltage drop specification, pretty much assures that any LN or LE  short circuit or fault of fractional ohms will trip the breakers quite promptly. The higher voltage lower current also helps with that.

Now of course there are always corner cases that will struggle, one might be a 50m extension lead snaking down the garden in skinny 1.5mm2 cable - being near that 16 AWG example,  perhaps plugged into a socket already marginal on voltage drop at full load. (so about an ohm there and back in the cable), and if the VD to the socket is the max of 5% (12V) at 13A (then a further ohm or so for that)  Here the PSSC at the end of the extension lead may be as low as 100A.

However while the 32A C type will be well on the thermal curve and may not fire until about 10 seconds, it is more likely to be a B type, and that will prompt -trip in many cases, and even if it does not, then the  13A fuse in the plug will get you within 3 seconds at 100A.


The US centric sizzling faults are not the kind seen here - the cables that stay live tend to blow to clear.

Mike

Alright, it seems we're all on the same page. And I'll add that not only is EFLI  is none existent in NFPA-70, but the CPCs are also grossly under sized. Just don't say that on a US forum.


So my question is: why are AFDDs being mandated through out the IEC market place?

mapj1:

The thing about the Pace consulting notes and the you tube videos is that they relate to 110V land, where installation practices are very different. 

I do not think you could set fire to a UK extension lead in a cardboard sandwich  and expect it to remain live and sizzling for very long at all, certainly only a few seconds, not minutes.

230V land regulations actually require us to verify Zs, and the L-N equivalent when we test PSSC, and that coupled with the maximum voltage drop specification, pretty much assures that any LN or LE  short circuit or fault of fractional ohms will trip the breakers quite promptly. The higher voltage lower current also helps with that.

Now of course there are always corner cases that will struggle, one might be a 50m extension lead snaking down the garden in skinny 1.5mm2 cable - being near that 16 AWG example,  perhaps plugged into a socket already marginal on voltage drop at full load. (so about an ohm there and back in the cable), and if the VD to the socket is the max of 5% (12V) at 13A (then a further ohm or so for that)  Here the PSSC at the end of the extension lead may be as low as 100A.

However while the 32A C type will be well on the thermal curve and may not fire until about 10 seconds, it is more likely to be a B type, and that will prompt -trip in many cases, and even if it does not, then the  13A fuse in the plug will get you within 3 seconds at 100A.


The US centric sizzling faults are not the kind seen here - the cables that stay live tend to blow to clear.

Mike

Alright, it seems we're all on the same page. And I'll add that not only is EFLI  is none existent in NFPA-70, but the CPCs are also grossly under sized. Just don't say that on a US forum.


So my question is: why are AFDDs being mandated through out the IEC market place?