Finished the firewall passthrough for the main power wire bundle. The instructions that come with the firewall passthrough I got from Spruce have you wrap the wire bundle in fire barrier cloth burrito style, then wrap that in silicone tape, stuff it in the tube, then tighten it down with worm clamps. I followed the instructions, but wasn't happy with the result. Seems to me that would let smoke and engine fumes find their way through the burrito into the cabin. With that in mind, I undid it all, then modified the installation to recess the burrito into the tube about 1/4". This way the next time I crack open a tube of fire barrier I can fill the passthrough tube for a nice airtight fireproof plug. This bundle contains the 8 awg wire to the main BUSS, as well as the shunt wires for the ammeter, and the wires from panel switches to the batt and start contactors. With that many amps running through there, I want to take the utmost precautions against chafing and shorts, so I wrapped the entire thing in Nomex split wire sleeve. I got this stuff surplus at the yard store a while back. It's the same product that I've seen in the gear wells of some big airplanes, as well as all over helicopters. It's really tough stuff, and also won't support a flame. Secured the bundle to the engine mount with hi temp adel clamps in such a way that it won't be able to rub on anything and will also be out of the way for ongoing servicing and future maintenance. I also played around with several different possible solutions for blade fuses on the ammeter shunt wires, but in the end, the simplest and neatest solution I could think of was just to use two screw together type in-line fuse holders utilizing 1 amp glass fuses I'm not a big fan of glass fuses. The small ones especially have such tiny filaments that they are sometimes prone to vibration induced failure. But in this case, it one fails the only thing that will happen is that eh ammeter will quit working. If it becomes a problem, I'll come back to this and reconsider something more complicated utilizing blade fuses, but for now this seems like a simple and tidy solution.