Thermal protection

[Jordanh1992]

When working out if a cable has the correct thermal protection, what do I do if for instance a 20A bs 88 fuse with an Ief = 230/0.92 = 250, how do I work out 't' from the fault current of 250A when Fig 3A3(a) shows me that a 20A bs 88 fuse disconnects in 0.1 seconds with 180A?

 

[telectrix]

use the 0.1 sec.

 

[Jordanh1992]

Okay thanks and also if say no correction factors are given, when it comes to working out 'k' what do I, it could be anything from the tables?

 

[Stroppy]

The K values are from the tables in the regs, and I seem to recall is generally 115