Fuse Size Question for Safetyhub

[uwjberg]

Hi all - more newbie electrical questions here.
I'm mid-stream in rewiring my 19' Sea Ranger.

Here's my wire sizing question thread and background of how I'm setting this up:
http://www.arimaowners.com/index.php?topic=20070.0

I'm about to install the battery switch, Safetyhub 150, and ACR. In doing this, I'm considering the fuse selection for the AMI fuses in the Safetyhub. I'm reading through this Blue Sea article on fuse selection:
https://www.bluesea.com/support/articles/Circuit_Protection/1441/Part_2%3A_Select_a_Fuse_and_Fuse_Holder_For_Your_DC_Product_Installation

I'm stuck a little bit here. I plan to have two 8 AWG runs from the Safetyhub. One to a fuse block and switch panel, and one to a fuse block that will run the GPS/FF, VHF, etc. If I'm reading the article correctly, the first consideration is the maximum value. Reading the chart I have approximately a 13' run of duplex 8 AWG (so I'm using the 25' spot on the chart). That suggests a 15A fuse if I use the 3% voltage drop (which I assume I should use?).

The second consideration is the minimum amps for the draws on the circuit. If I add up the total amps of each product I come up with 16.9 amps for each fuse block. The article suggests multiplying that by 125%, so 21.1 amps. More than the maximum I came up with?

The question is, should I be using the 3% voltage drop reference? If I use the 10% voltage drop for the maximum, it would be a 40A max, and a 21.1 minimum, meaning a 30A fuse would work for each run.

Am I looking at this correctly?

[DevMah]

The max for AWG 8 is 60A outside the engine room bundled wires as you are running duplex.
You min calculation of 21A is correct.

So 21A being the minimum and 60A being the max gives you a fuse of 40A in the middle.
Fusing has nothing to do with voltage drop, it's based on 125% load, the max value the conductor can handle, and meeting the mid point of the two.
Dev

[uwjberg]

Dang it - I was looking at the wrong chart. I see where you got the outside engine room amp rating. I feel a bit foolish now.
Appreciate the response Dev - once again saving my bacon.