[330Jock]

I have a question for our wonderful brain trust. I am finally trying to finalize my electrical system before panel build. When I look at the AeroConnection drawings for the supply wires from the battery contactor to the supply buses, I am not seeing any protection for those wires. Is that correct? So, the #8, #10. and #12 wires going into the aircraft to either fuse boxes or breaker panels have no protection?
Also, while I have you here, what's the proper ANL fuse on the b lead for a 60amp alternator? I've seen 60, 70, and 80 amps.
Thanks guys!

 

[MCA]

I have a question for our wonderful brain trust. I am finally trying to finalize my electrical system before panel build. When I look at the AeroConnection drawings for the supply wires from the battery contactor to the supply buses, I am not seeing any protection for those wires. Is that correct? So, the #8, #10. and #12 wires going into the aircraft to either fuse boxes or breaker panels have no protection?
Also, while I have you here, what's the proper ANL fuse on the b lead for a 60amp alternator? I've seen 60, 70, and 80 amps.
Thanks guys!

Bill,

That's correct, there is no fuse there. Turning off the master switch if you smell or see an electrical fire is the solution here.

The b-lead fuse is sized based on the size of the wire to the alternator.

 

[dmattmul]

Also, while I have you here, what's the proper ANL fuse on the b lead for a 60amp alternator? I've seen 60, 70, and 80 amps.
Thanks guys!

Review the specs of the ANL fuse you are going to use. The "Midi" type ANL's seem to have a lower actual current vs time than the standard sized fuses. Most ANL fuses can withstand for an unlimited amount of time 50% overage in amperage. My 60-amp alternator I've seen 70 amps for several minutes and use a 60-amp standard ANL fuse. Earth-X batteries have amp limitations so that is something else to watch. (If the next owner decides to upgrade to an Earth-X battery)

 

[330Jock]

Review the specs of the ANL fuse you are going to use. The "Midi" type ANL's seem to have a lower actual current vs time than the standard sized fuses. Most ANL fuses can withstand for an unlimited amount of time 50% overage in amperage. My 60-amp alternator I've seen 70 amps for several minutes and use a 60-amp standard ANL fuse. Earth-X batteries have amp limitations so that is something else to watch. (If the next owner decides to upgrade to an Earth-X battery)

Bill,

That's correct, there is no fuse there. Turning off the master switch if you smell or see an electrical fire is the solution here.

The b-lead fuse is sized based on the size of the wire to the alter

Bill,

That's correct, there is no fuse there. Turning off the master switch if you smell or see an electrical fire is the solution here.

The b-lead fuse is sized based on the size of the wire to the alternator.

Bill,

That's correct, there is no fuse there. Turning off the master switch if you smell or see an electrical fire is the solution here.

The b-lead fuse is sized based on the size of the wire to the alternator.

Thanks for the quick reply guys!

 

[330Jock]

Bill,

That's correct, there is no fuse there. Turning off the master switch if you smell or see an electrical fire is the solution here.

The b-lead fuse is sized based on the size of the wire to the alternator.

Marc,
Understand about busses being isolated with battery switch. What about a hot battery buss for electronic fuel and ignition?

 

[johnbright]

... When I look at the AeroElectric Connection drawings for the supply wires from the battery contactor to the supply buses, I am not seeing any protection for those wires. Is that correct? So, the #8, #10. and #12 wires going into the aircraft to either fuse boxes or breaker panels have no protection?

Ref FAR 23.1361 Master Switch Arrangement.

Which Z template are your looking at?

Respect the asterisks that Bob Nuckolls uses. * = "as short as practical".
I say "Keep these wires as short as practical. Fabricator should be confident that a short to ground is practically impossible."

... what's the proper ANL fuse on the b lead for a 60amp alternator?

According to me it would be Bussmann ANL 60 current limiter but I would use Littlefuse MIDI 100 fuse because it is physically smaller.

• Bob Nuckolls is currently recommending a fuselink 4 awg smaller than the B lead as a simple solution but both the Bussmann ANL 60 current limiter and the Littlefuse MIDI 100 fuse open with less energy (even considering the smallest fuselink that could be used, 12 awg with 8 awg B lead) and will not nuisance blow.

 

[johnbright]

... What about a hot battery buss for electronic fuel and ignition?

For EFI+I I developed a power schematic that I of course believe in.

• I'm in the two alternator one battery Z101 camp.
• I have two schematics:
  • Both have an engine bus and range with a failed alternator is defined by fuel.
  • The one I call bookshelved legacy has two wound-field alternators, one on the main bus and one on the battery. Find it in folder 1) D) here as the PDF named "Elec Schem N1921R Z101...pdf"
  • The one I call production intent has a wound-field main alternator on the main bus and a Monkworkz permanent-magnet generator on the engine bus. Find it in folder 1) A) here as the PDF named "Power Schem N1921R MZ-30L on engine bus...pdf"
  • Both of these keep the engine running in the smoke-in-the-cockpit-main-master-off scenario and also respect FAR 23.1361 Master Switch Arrangement.