The AeroElectric Connection has an interesting idea for high current fuses on
their web site at aeroelectric.com. The area to see is appendix Z, page Z-2.
Their concept is that a 4 inch length of wire, at least 4 wire sizes smaller
than the wire being protected, will work as a fusible link by heating and
opening before the protected wire is damaged. Damage is limited to melting of
the insulation on the fusible link plus heating of anything touching it, so
try to isolate the link and/or insulate it with a fiberglass sleeve. Fusible
links may be purchased at auto parts stores or made from pieces of tefzel wire
using crimp terminals. Fusible links are apparently used in cars to protect
certain areas of wiring from screwdrivers dropped into the works.
In my installation I wanted the breakers in the panel but this left the wires
between the master relay and the breakers (including the panel connectors)
unprotected. I added a fusible link to protect these wires, unlikely as a
failure here is. Of course, since the link is about 25A and the panel
connectors are rated at 15A per pin, a connector meltdown is still possible if
a short occurs in the panel....
Another fusible link was added between the alternator's regulator and the
capacitor. These links replace the high current fuses called for in Europa's
diagram. I added fusible links on the wires controlling the master and
starter relays for the same reason. All fusible links are on the engine side
of the firewall (to avoid smoke in the cockpit) and are positioned to be
easily accessed.
For those who are using AMP's Mate-N-Lock connectors for the panel, the pin
extraction tool is relatively expensive at $14 -- so naturally I didn't order
one since I assumed that I could insert the pins in the proper positions
flawlessly. Naturally, old fumble fingers managed to get one in the wrong
place early on. A usable extraction tool can be made by drilling out an inch
or so of a 3 inch length of 1/8 inch brass tube (available at hobby shops) so
that it will slide over the pin - cost is less than $1.
John A044 Newtown, CT
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