Permanent 12v under passenger seat?

[Pembo]

Think I just had a bit of a brain fart before, will let you know how I get on as the weekend is when it's planned.... Out of interest the additional cables under the passenger seat and the one with the black tape over it, possible to use as my live into the Isolator or just take one from the battery as best practice?

 

[The Bear78]

It could be. I am not overly familiar with its size (rating) or how it is fed as I didn't have one.
I ran two new cables from under the battery, directly onto the fuse bar and added inline midi fuses as close as possible.

 

[Tsixty]

I know it has been asked before but I just want to be completely sure before I run new wires. 2019 Kombi with pretty standard unmolested electrics. Is there definitely not an ignition switched live under either the driver or passenger seat? Doesn't need to be high capacity as I only need it to power a single USB socket for something that I want under one of the seats.