i feel like you made up that backstory just to make your point seem more valid <| sep |> sidebar ? or wiki <| sep |> Funny you should mention that because I bless the rains down in Africa . <| sep |> I would like it if they could add a counter as to how many times it ' s been proc ' ed so I can see if it ' s being used . <| sep |> I was thinking of individual 1 a fuses on the 5 v side is this enough ? USB 3 . 1 has 3 A as part of their specs for 5 v . Nominally , USB 2 . 0 only is supposed to go up to 0 . 5 A 500 mA , but I bet you there are plenty of fast charge devices that will grab more than that . You ' ll probably want 3 A fuses if you ' re aiming at USB 2 . 0 . 6 A if you ' re doing USB 3 . 1 fast chargers . And by fuse , I mean you want a detailenbelfuseinc 0 ZCG 0150 BF 2 C 50717732 ND 4156109 unless you really do plan on having the engineers come onto the train every few days to replace fuses aka whenever a noncompliant device is plugged into your ports