Follow the steps:
1. Open Wire Sizes window. Define the specification and c.s.a of 4mm square for material code TWC. (Just an example value)
2. Open Component maintenance window and create the wire with material code TWC and go to its wire attributes tab and now you will have the specification created in step1.
What is the relation `specification' <-> `CSA'.
Do you have a convert table for that?
Specification is a user defined field and normally users would define it:
1. Gauge of the wire, For Example AWG1 , AWG2 etc. According to the gauge, you will have cross sectional area of the wire.
2. Manufacturing specification of wire for example: 17/0.3 i.e. 17 turns of 0.30 mm diameter.
3 Resistance of the wire
4. Maximum Amperes of the wire.
I don't have any convert table. But it should be manufacturer responsibility of the wires to provide you the appropriate specification chart of the wires.
I hope it helps.