I have a separate relay for my heatbed which is wired into D8. D9 and D10 are wired to two separate e3d V6 hot ends. Each Hotend draws 40W/12V=3.3A of current. Considering that D9 & D10 (and everything else except the heat bed) share the same 5A circuit, how come I'm not blowing the Ramps board 5A fuse when I heat both of the hot ends at once? I've even modified my start script to actually heat them both at once from a cold start. Can anyone explain why this works? Anyone think it is a bad idea?

Since it seems like a bad idea to run both hot ends form the same 5A circuit I am thinking of controlling the heatbed relay with D9 and moving one of the hot ends to D8. This would utilize the 11A circuit path for a single hot end, and lump the tiny amperage used to control the heat bed into the normal 5A circuit with a single hot end, motors, electronics, etc. Does anyone have an opinion on this? It should be as easy as swapping the pin assignments in Marlin right?