IEC 61439-1 - Relationship between prospective fault current and diameter of copper wire

Hi,

I am currently reading through the standard IEC 61439-1 - Low-voltage swtichgear and controlgear assemblies - Part 1: General rules, and on Table 14 it is stated the "Relationship between prospective fault current and diameter of copper wire" (see picture attached).
I don't understand why the references of the copper wire diameter are so low. Based on this values you will have a very low cross sectional area of the wire. How come for example a 0,8 mm diameter copper wire can withstand 1500 amps ?

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