I don't know why I get so confused with the Wire size and fusing in this project. And it comes across in my writing. I think I write faster as I am thinking about the setup and its comes out wrong.
The 12 ga wire and InLine Fuse Holder I have, is for the Ground Wire from the ACR to the Ground Bar.
So what I need to know is the Wire Cable Size from the ACR to the Battery Banks and what type of Fuse Holder I get before both battery Banks.
I have 2/0 Cables now, both Ground and Feed wires to each bank. So I am thinking I should get the same size (2/0) for the ACR. But what Fuse Holder? And what size Fuse?
As "dlochner" (Dave) has suggested, a 6 ga cable fused at 75-90 is great and thank you. And I plan to do just that, either in 6 or 2 gauge.
Where is this type of Fused Cable available? Or is it a Cable to a separate Fuse Holder that I attach to each Battery?
Thank you again for bearing with me and thank you Dave.
If you are using a Blue Sea ACR, I don't understand why you would be installing a 12 AWG ground. The instructions show a 16 AWG ground wired to the negative buss. It shows a 1 amp fuse, which is very small. Typically, people use one of those in-line holders with a small glass fuse or a spade type fuse in these small sizes. That's all you need on the negative side.
For the positive side, you would select a cable depending upon the charging amperage. Dave is suggesting using 6 AWG from the ACR positive terminals to the battery bank positive terminals. You should have a fuse at the battery terminals or within 7 inches of the battery terminals. He is suggesting 75 (minimum) amp fuses for each battery terminal. You are not going to do this with "in-line" fuse holders. There are a variety of fuse holders made and you should read about each style and determine which is best for you. I have used MRBF fuse blocks directly on the battery terminals and have been pleased with the installation. Another style that you should consider is MEGA/AMG. These are intended for larger fuses.
I think that 2/0 Gauge is far larger a cable size than you need for the cables between the battery banks and the ACR. You have 2/0 for the battery leads, between batteries and the system ground (negative) and from batteries to the selector switch (positive). You should have the positive cable fused at the battery (one fuse for each bank). These would be larger fuses, and again, you need a proper fuse terminal for each fuse. The MRBF conveniently makes a fuse holder with a double holder so that you can have 2 different fuses at one location serving 2 separate cables (one for the battery cable to the switch and one for the ACR cable going to the ACR.
To limit your confusion, you must consider that the purpose of the fuse is to protect the cable or wire from melting at over-amperage conditions. Basically, the fuse protects the
wire. The fuses at the battery aren't intended to protect the battery or any devices. The fuse must be sized to accommodate the cable or wire size, that's it. Some devices, like radios and electronics, use a small "in-line" fuse intended to protect only the device. That's why you often see a small fuse holder attached to the positive lead from an electronic device. Keep in mind that when you step down in cable/wire size, you should have a fuse where the step-down occurs. This probably occurs where the battery cable is attached to the selector switch and then there may be something like a 6, 8 or 10 AWG leading to the electrical panel. You need a fuse there to protect the smaller wire leading to the panel. You probably have a 2/0 cable from the selector switch to the engine starter. You don't have a step down there so you don't need an additional fuse.
Study all of the wiring diagrams that have been posted. They will help understand.
