Amtech Cable calculation - BS7671

[NickParker]

I have attached a cable verification sheet made in Amtech software.

What is Iz? I do not know how this value arrived at in the attachment; I tried to do the calculations using the derating factors, but the values are not matching?
What is It? Is it the actual ampacity of the cable without any derating factors?
What is meant by simultaneous overload?

Thanks in advance.

 

[NickParker]

Got the answer from BS 7671, but still got another question on the previous attachment.

How the Source end / Load end phase fault current is calculated? that too with a max and min values??

 

[RodneyDixon]

General Form:
Iz = In / (Ca * Cg *...)

For adjustable protective devices:
Iz = Ir / (Ca * Cg *...)

Iz is the minimum cable current carrying capacity - see BS7671 Appendices 4.5 as per sheet.

It is tabulated current carrying capacity of cable with derating factors.

Simultaneous Overload - can the other cables on the cable tray that are alongside your cable be subject to simultaneous overload?? (heat).

Ensure you are using derated cable temperature impedance in your manual calculations.