Answer / ramesh kumar k

the size of the cable depends upon the material used in the
cable...

if u go for copper cable... the copper has got the current
carrying capacity of 2A/sq.mm continuously with out
overloading effect. so if you want for 550A,

550/2 = 225 sq.mm copper cable u have to use...

i think it is 1.2A/sq.mm for Aluminium...

550/1.2 = 458 sq.mm Aluminium cable u have to use...

like this.... the current carrying capacity is different
for different materials...

Answer / dilip singh

Normally if you go with the size of cable in catalogue, you
will observe the if cable is of 400sqmm thenit carries
about 300A current and similarly for other ratings so you
can guess by size of cable selected. but it will not be
correct all the time. may it will vary by some value.

Answer / u.chandarasekar

It is very vert Hard Question for me i never know the
answer.
In 28 Years exp. first time i face this kind of qus. That's
a main reason BGR Energy Terminate me.

Answer / s.manikandan

we are know the formula R=Pl/A. P - resistivity of copper or
Aluminium, L - Length of wire,A - Area of wire, and We use
I=V/R formula

Answer / sk

In copper cable 1sq.mm equals to 4 amps so 150sqmm*4 amps that equals to 600 amps , and we will be in safer side

Answer / syed masood

t he cable size depends upon the ams rating but the cables size defined standard value the ams rating enclosed this values some values 2.5,4,6,10,......630
first you have to know full conductor size standard value
then you calculate cable size depends upon the ams by using this relation cu=2-5ams per sq.mm
al=1.2-2ams per sq.mm
4 guage for 125-150ams convert guage into mm
from kadayanallur syed masood electrical engineer
national college of engineering

Answer / amit

u van not get tha exact size of cable widout catalouge

Answer / binay agrawal

generally, for low rating full load current should be 3
times for aluminium cable, & 4 times for copper cable.
so, here 550/4=137.5 sq mm,
also 550/3=183.33 sq mm.
but this is for low rating, in high rating ratio is
decrease,
i.e. for copper 550/3= 183.33 sqmm
& for aluminium 550/2= 275 sq mm.

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