6AWG for 60 amp alternator

[prkaye]

For the run from my ANL limiter on my firewall to my PlanePower 60 Amp alternator, will 6 AWG wire be ok? Vans calls for 8 AWG for their configuration, which runs from the Alternator breaker (presumeably in the cockpit). But that's for a 35 Amp alternator.

[Jeff R]

6 AWG should be fine. That is what Bob Nuckolls recommends for a 60 A alternator.

[FredMagare]

Phil,

I'd imagine it's a short run of wire, so it should be adequate. (I'm going with 6AWG with a 40amp alt.) Check this link for more info: http://www.aeroelectric.com/articles/wiresize.pdf

If you're still in doubt, go with 4AWG. Not only will it give you a greater margin for safety but probably some peace-of-mind, too!

[Jamie Aust]

I know this is an old post, however looking at the posted link, 6AWG is only good for 54 Amps. I was going to use 6 AWG. Should I be looking for some 4 AWG now ? Has anyone flying used 6 AWG with no problems.

[apkp777]

You can use 2 8 gauge wires identical length.

[mike647m]

I used the same red 4 AWG welding cable positive battery cable for the alternator.

[Camillo]

Jamie, maybe I do not remember correctly, but I have a B&C L60 alternator and wire it to the ANL with 6AWG. I remember that the 54 amp limit is for the 8AWG. The 6AWG can withstand continuous up to approx. 70 and more amp.. I looked at the 43.13, on the 150? column Tefzel cable.

Unless you do not squeeze your alternator to develop all the 60 amperes, the 8AWG should be fine. But provided that cable is not protected, I think 6AWG should be better.

Camillo

[shuttle]

Jamie,
Camillo beat me to it. I have the PlanePower 60A alternator and am planning on using 6AWG cable. My 6AWG is from B&C and is M22759/16 rated to 150 deg C. My planning too is also based on AC-43-13-1B.

Table 11-9 in AC-43-13-1B (Copper wire, continuous duty) gives 76Amps max for 6AWG cable rated to 150degC. Note though that this table is actually for cables in groups, harnesses or conduits at 60,000ft! At lower altitudes and with a single wire to better disipate heat, the max amps ought to be even higher. This table gives max amps of 103Amps for 4AWG and 57Amps for 8AWG, again both for 150degC rated wire.

For another datapoint, note that Table 11-3 gives a CB protection value of 80Amps for a 6AWG cable (but with wire spec of MIL-W-5088, which I am not familiar with). This table also says protect 4AWG with 100Amp CB and 8AWG with 50Amp CB.

Finally, regarding voltage drop, 4ft of 6AWG cable carrying 14V/60Amps has a voltage drop of just 0.095volts which is using up about 20% of the suggested max voltage drop of 0.5volts all the way to your endpoint device. Using 4AWG for this 4ft run you'd have a drop of 0.06volts or for 8AWG the drop is approx 0.15volts.


Hope that helps.

[hgerhardt]

Check and see what your car uses. Mine have a 140A and another a 130A alternator and both use 6 gauge. 8 gauge is fine for only 60A. Remember, how much time is the alternator actually making full output? Right after engine start, and then quickly tapers off. Save the weight. And the stress on the B+ stud.

Heinrich Gerhardt
RV-6, 331 hours with a wimpy 8ga wire and 70A alternator

[Jamie Aust]

Thanks everyone, 6 AWG it is then.