On Fri, 11 Mar 2005 09:24:23 +0100, Bert Willing wrote:

There are components which are not fused internally (i.e. T/S indicators,
Colibri etc).

Bimetal breakers are disastreous in this case as they are very slow and will
ultimately less pass about 10 times the nominal value before cutting off.
This winter I was loocking into replacing my fuses by breakers, and I
decided that I didn't want to have this crap in my gliders. The breakers to
use are magnetic ones which are pretty fast - but the price tag is very
different... so finally I kept going with fuses.

Fuses for individual instruments don't protect those instruments, but
do stop the larger battery fuse from blowing if the instrument fails
in a way which draws a high current from the battery.
This only works if the individual instrument fuses have a current
rating smaller than the common battery fuse.
If the common battery fuse blows, you lose ALL the instruments. If a
single instrument fuse blows, you lose that instrument, but you were
going to lose it anyway, as it is the failure of the instrument which
blows that fuse.
Cheers, John G.