At less than two feet I wouldn't worry about it. There will be more
potential resistance in the connections at the ends of the wirer than
in the wire itself.

Mike Rapoport wrote:
The length of the wire is less than two feet and the avionics draw less than
15A when not transmitting so voltage loss isn't really the big issue. I
assume that they used two 12ga wires for flexibility compared to a single
8ga wire.

Mike
MU-2
Helio Courier

"kontiki" wrote in message
...

Your should use the biggest wire you can comfortable use so it will
contribute
the least voltage drop under the full load of all avionics and electrical
systems. 12Ga wire is typically rated for 20amps continuous. I would try
to
go with al least 10GA or even 8 if you can work with it. Basically, in
that section of the circuit (before the breakers) the bigger the better,
within reason of course.

Mike Rapoport wrote:

In my 1974 Helio Courier, the avionics bus is powered by a contactor that
is activated by the avionics master switch. There is no circuit
protection between the contactor and the avionics bus. The wiring
between the contactor and the bus consists of two 12ga wires. There also
doesn't appear to be any circuit protection in the field circuit for the
avionics contactor. It seems to me that since there is no breaker
between the contactor and the bus, the wire size should be sufficient to
supply the rating on all the avionics CBs (32.5A total), but I don't know
what the absolute maximium permissible temperature rise is before the
avionics CBs pop. Would one 12ga wire be sufficient between the
contactor and the avionics bus? Also, am I looking at the problem
correctly, sizing the wire considering all the avionics CBs to reach
their limits simultaneously?

Mike
MU-2
Helio Courier