building basics
As you can see from this chart in AC 43.13-1B, the wire size for the same run with a 12-volt
versus 24-volt system is several gauge sizes smaller, which means less expensive wire and
less weight per foot of wire run.
a premium to the price. You will
also need to contact the fixed base
operator to use its power cart to jump
a 24-volt electrical system, or opt for
the higher price of a 24-volt charger
with a power charge/jump feature,
which would allow you to use your
charger to accomplish this function.
The last disadvantages come
in the area of alternator price and
availability. Due to the nature of the
24-volt electrical system, there are
not a lot of aircraft sitting in salvage
yards, waiting for you to cherry-pick
the 24-volt alternator or regulator. You
will probably be driven to purchase
new electrical equipment, which will
be available for a premium at the sales
counter when compared to the price
of used equipment.
Choosing the Electrical System
for Your Aircraft
You can see the relative advantages
and disadvantages of both electrical
systems. In some cases, the selection
will come down to owner preference.
However, in cases where the pilot
wants to install air conditioning or
an electrical prop and wing de-ice
system, the 24-volt system ends up as
the hands-down winner.
As a general point, a
builder can, with only a
few exceptions, decide
to take the 24-volt route.
The same cannot be said
with the 12-volt system…
The main reason for this is simple:
air conditioning or a de-icer draws a
great deal of power. The higher voltage
means you will be able to purchase a
100-amp alternator, which will allow
you to use the various equipment
you have in your airplane without
any restrictions or trade-offs in the
installation. Of greater importance
is the point that at present, there are
no 12-volt air conditioner systems for
aircraft being manufactured, so if you
