Electrical System Article from 2015

I just read an article by Jim Cavanagh from 2015 called “aircraft electrical systems in 1,000 words.” Jim mentions that we use DC in airplanes instead of AC because we can use smaller gauge wires. I think that is completely wrong. We use DC because we have to operate with a battery, which is DC. It’s easier to convert from AC (alternator or generator) to DC than vice versa, which would require an inverter. This is why we use DC in our cars too, where weight is not as critical of an issue. If we compare 12 or 24 volts DC to what we use in our houses, 120 or 240 volts AC. For the wire run lengths we use in planes, we would use much smaller gauge wire for AC, because we would need 1/10th the number of amps for the same number of watts. Granted, you can only go so small before you run into handling problems, but that is not the discussion.

Am I missing something obvious here?


  • Scott ShererScott Sherer COO Forum Moderator

    It would be very nice to have him read your post, above. It's seven years later and he may have completely forgotten about the article by now. However, I'm in agreement with you. On a related note, the larger airplanes from 50 years ago had 400Hz systems to power the avionics of the day so they had both DC and AC.

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.

    Need help? Let me know!

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