Cable calcs

[snowplough]

Hi Guys,

If i remember rightly, when doing cable calcs , first you work out the design current , say it was 47a, then you take it upto the nearest fuse size 50a, then look in tables to find correct cable csa.
Going on the above scenario ,say it was ref method c , page 131 O.S.G gives you a csa 0f 10mm square, if im reading correct .

At 46a it is 6mm square just outside .

Regards

Locket

 

[snowplough]

Cheers Amp David,

I just dan't understand how an appliance that needs 47A to run Can be down graded to 45A.
Because of my lack of knowledge i would just stick to what i have been taught ie. Ib is less then or same as In.

Regards

Locket

 

[Amp David]

Agree with you. Thats what I would have done if i were desiging the circuit

 

[Mr.Si]

Also, if you then install the "Lower" rated Cable / Protective Device and the customer then has problems and decides to take you to court over it...

It could cause you problems if you've not done it in accordance with the Regs book, as they tend to wave that around in courts don't they?

I too would err on the side of caution and use higher rated cables.