17th Edition - Max Disconnect Times

[martynp]

Done my 17th but slightly confused following a conversation since course.

Guidance Notes 3 give you a combined table for 0.4 & 5 secs disconnect times, but regs still seperate the two.

Heard recently that we only have to bother with the 0.4 disconnect time for all circuits.

Any thoughts

 

[EasyFox]

Yep 0.4 is the way.
Unless
1, It's a distribution circuit rated above 32A on a TN supply then 5 sec diss con can be used
2, TT system 0.2 if no bonding to extren conductive parts
3, TT sytem 1 sec diss con for a distribution circuit & for circuit rated above 32a.

You need to take a look at 411.3.2 through 411.3.2.6