[jnsaff2]

Transformers only work with AC. Isolated DC-DC has also transformers where there is really high frequency AC. DC->AC||AC->DC. It's all hidden and due to high frequency quite small. But still AC.

Re cabling: currently we have 230V at home, going to 24VDC would mean 100x more losses. So I would say I got it correctly when I said going to 24V or 48V needs thicker cables due to increased I. As for your sentence, you don't NEED thinner conductors when voltage goes up but you would be quite wasteful if you didn't.

[R0b0t1]

Yes, but it's not AC in the sense that most people think of AC, where it's oscillating around 0V. Cable comment was related to you mentioning 12 and 24, it didn't seem compared against 120V in your comment.