Answer / vishvendra singh

we know that current capacity of Alluminium conductor is 2
AMP/sqmm. thats by In normal condition 300sqmm cable current
capacity -600 A & 150 sqmm capcity is -300 A.

Answer / k.k dash

now a days company manufacture lower gauge of aluminium cable for there own profit,previously 300 sqmm alu cable can take 600 amp,bt now a days 300 sqmm will take 300*1.2=360 amp at 80% load which is healthy for user,same way 150 sqmm will take 150*1.2=180 amp

Answer / 7anoter4

It depends on lot of factors. The duration of the load:
short-time[as in short-circuit case],continuous load,
intermittent load. It depends on also on ambient type [air,
underground-direct laid or in concreted duct],on thermal
resistivity of the ambient [if it is in underground],on
ambient temperature, on insulation type[bare, pvc, xlpe,
epr etc.] and other factors.

Let's say in short-circuit case for 1 sec 300 square mm
aluminum conductor pvc insulated. Permissible temperature
[for PVC short-time]= 150oC.Ambient air 30oC.
Ipermissible=27 kA[27000 A].

For the same cable in open air 30oC[NEC Table 310.15(B)
(17)] continuous load [75 oC]600 MCM=300 sqr.mm permissible
545 A

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