-----Original Message----- On Behalf Of Orma Robbins A 100 watt landing light in a 13.5 volt system pulls a current of 7.4 amps and could use a 7.5 amp fuse or CB if you don't consider wire length. ----------------------------------- I would never try to protect a circuit with a fuse or breaker that close to the draw of the device -- most loads pull heavier current at start-up, system voltage will fluctuate 20% or so depending on whether you are drawing on battery or under charge. Your fuse is there to break the circuit if there is a short in the circuit that would pull fire-starting current otherwise, you don't want it so close to the load amperage that it cuts off your landing lights because of a transient voltage spike.
Fuse this light with a 10 A or 15 A fuse, size the wire accordingly. I'm still not sure what I think of Mark Langford's two-systems no-fuses approach. Never heard that one before -- is that in the AeroConnections book? I'll have to get that and read it, I'm always willing to learn. I like fuses, they can isolate a faulty circuit so the rest of the system keeps working. With no fuses, a fault in any load on any circuit can draw it all and shut everything down while it is trying to make stinky smoke. I guess if you have a complete second system to switch to, OK, but if you develop a short in one instrument, wouldn't you rather have one fuse pop, one instrument go dead while the rest keep on, than shut it all down? Seems to me that shorting instrument could shut your second system down as well as your first. Just trying not to test the trapped-smoke theory . . . Rich H. Meyer cpt...@npcc.net Phone 574-642-3963 Cell 574-202-3920
