Previous owner mayhem

[Rob_the_rich]

so I can now install a twin 13A socket on a bit of 2.5 T&E less then 3m fed from my cooker switch , that is going to get me out of so many holes , Life is good 

wouldn't comply with 434.2.1, no socket outlets.

 

[poni]

drat foiled again, darn those pesky kids 

 

[apprentice87]

Fault current protection is afforded by the RCD. No need for fault current protection to be at point of reduction either (434.2.2) provided it complies with 434.5.2, which is where a bit of calculation is needed 115x115x1.5x1.5= 29756 which should be greater than the I2t of the RCD and probably of the mcb too.

Sure about that are you??? And what about line neutral faults????

john..

 

[NozSpark]

Sure about that are you??? And what about line neutral faults????

john..

Line Neutral "faults" come under over current protection,,, not fault protection

 

[Andy™]

Line Neutral "faults" come under over current protection,,, not fault protection

no they dont. L-N has to be protected against both fault and overload, there are some exceptions to both, but generally the removal of fault protection will not apply to anything domestic

earth fault currents can be protected by RCD where Zs cannot be met, but L-N must still be protected in the usual way with a fuse or MCB etc

 

[Rob_the_rich]

Sure about that are you??? And what about line neutral faults????

john..

yeah, sorry about that. I guess I was thinking of the worst case scenario with the t&e cpc being smaller. Or maybe it was just another brain fart.

doing the calcs for a bs60898 63A type B mcb, from the table in fig34A byb, we get I=315A so IxIxt=315x315x0.1=9922.5

this is less than the 29756 value of k2S2 for 1.5mm

for a 100A bs60898 type B bs60898 we get 500x500x0.1=25000 which is still less.

but a 125A one will fry the insulation of a 1.5mm conductor (625x625x0,1=39062.5)

Can't see that one being used much in a domestic anyway.