I have my 12v side already setup in a van conversion and I'm about to add the MultiPlus 3kw.
I have 3x 200ah batteries with 300amp MRBF fuses at their terminals, in parallel brought together with 120mm2 cable to battery posts.
From the posts, 120mm2 cable connects the bus bars.
The MultiPlus will connect to the busbars via a 400amp T Fuse and 120mm2 cable again.
Should I also have a 400A T Fuse between the battery posts and busbar?
My original wiring diagram had this, but I then opted for the terminal fuses, and an electrician said the extra 400a in the single cable from the post therefore wasn't necessary. I'm now thinking that single cable is not fused correctly (as the 3x 300A MRBF fuses combined are too high) to the bus bar, except for the fuse between busbar and MultiPlus which is (I believe) the only route for that amount of current to run without blowing another much smaller fuse.
Thanks in advance!
And thank you all for your contributions across this whole community, it has been very useful in my learning.