OK, I'll ring in on this one.
The amount of voltage a conductor will carry is a function of its insulation, not cma.
Braided, and stranded conductors are used for 2 reasons in AC.
1. Ever try to pull anything larger than #8 in solid wire? Let's just say it don't corner too good....no "Wider is Better" here
Linemen use solid wire all the time in larger sizes, if you can form it outside the conduit, no problem, just a little more difficult to work with.
2. Never forget that AC has a property that is completely different from DC. Skin effect. Which means that current tends to travel on the outside of conductors and ignores the inside (on 400 hz, I've installed tubing cause the inside ain't being used anyway), so it is more efficient to 'break up' that pattern by using many strands and allowing it to 'skin' in multiple layers. The higher the current, the more efficient to use stranded or braided conductor.
That do it?