Conductor size

[brightspark26]

I'm doing the distance learning course to then do my approved electricians exam. The question being asked is.
Determine by calculation the size of the main conductors between the main switch and the db. Including earth
so it's a 100A supply ambient temp 25.c in 100x100 trunking distance 2metres from each other.
I think my factors are
In-100A
Ca - 1.03
Cg-not sure ? 0.65 ?
Ci- NA
Cc- 1
my answer came out to be 151.51 Amps then requiring 70mm cables
any help appreciated

 

[Leesparkykent]

I'm doing the distance learning course to then do my approved electricians exam. The question being asked is.
Determine by calculation the size of the main conductors between the main switch and the db. Including earth
so it's a 100A supply ambient temp 25.c in 100x100 trunking distance 2metres from each other.
I think my factors are
In-100A
Ca - 1.03
Cg-not sure ? 0.65 ?
Ci- NA
Cc- 1
my answer came out to be 151.51 Amps then requiring 70mm cables
any help appreciated

Deleted

 

[brightspark26]

Yeah I looked at that but I've to work it out by showing the calculation.

 

[Richard Burns]

You need to know the design current, i.e. what load will the run be taking.
perhaps you could decide on 100 A .
You have no grouping, your ambient temperature is right, you have the installation method of singles in trunking (B) (effectively insulation but accounted for)
So I am not sure where you got 151 A from or what this 151 A refers to.
Try showing your full calculation.