Avionics: Modified fuse block to support buses.

I wanted to use three buses for my avionics.  That topology is explained in this earlier post.  It required 29 fused positions.

Turns out that, short of ordering in lots of 1,000, obtaining a fuse block that has the three buses as I wanted them (13, 9 and 8 positions), wasn't going to happen.  So I obtained a 30-position fuse block that is independently wired.  The 60 A breaker for the alternator is a "Mechanical Products 1648-009-060-015" from Waytek.

This required me to have power distribution blocks, in the same way one would have ground distribution blocks.  I needed three of them, one for each bus.  So that's what I designed and implemented.  Below are the Master and Avionics 1 buses (top left) and the Avionics 2 bus (top right).  They are unsightly, as the hot side of each fuse is connected to the respective bus.  However, they indeed functioned.  The bottom left image shows the multitude of wires going to the fuse block.  And the bottom right shows that it can look pretty when finally installed.

But, I just didn't like that setup.  There was no good way to cover the positive distribution blocks, which represented a risk I wasn't comfortable with.  Then, one fine December day, it struck me just how to fix this problem...

First I cut up a bunch of wires and attached the fuse blade terminals to each wire.

Then I created my own buses by using high gauge wire to connect each fuse position appropriately.

Each bus wire was tinned (left) and then each fuse wire was soldered to the its bus wire (right).  It's worth noting that a 140 Watt soldering iron was necessary to generate enough heat to make this happen.  There is a lot of wiring here acting as a very effective heat sink.

Each bus was then insulated with heavy poly tubing.  This reduces the possibility of chaffing (especially since the solder wasn't smoothly applied) and shorting.  Below shows the nine position Avionics 2 bus.

Here is how the 13 position Master bus was setup.

After ripping out my original setup, I could install this new one.  Here is the back side of the new fuse block after it was installed.  Each of the three buses is apparent.

Four wires go into the output of the 60 Amp breaker.  The input of course being the alternator.  The output has the battery, the Master bus and both Avionics 1 and 2 buses.  The visible metal is the only portion of the positive polarity in the electrical system that is exposed.  I'll find a way to cover it gracefully.  A MS-25171 nipple may be the way to go.

This was exactly 16 hours of work.  A great waste of time and money to fix a self-created problem.