12 or 24V?
 

I feel like I should already know the answer to this question, but here goes. Are the wiring harnesses provided by Van's for the RV14 designed for 12 or 24V systems?

The wire sizes were all appropriate for 12 which means they would work for 24. I'd be very surprised if anyone is building a 24v Rv-14, but the wiring will work.

If you're contemplating building a 24v RV-14, I'd be curious to know why. My guess is that with so little weight savings in downsizing the wiring for 24v the battery needs would raise the weight. I haven't really thought about it however, seems like a lot of complications at first blush.

I think the main advantage of 24V systems in small aircraft is engine cranking power and battery endurance after a failure.

With modern starters engine cranking isn't an issue.

Arguably the default battery on the -14 doesn't have enough power for proper IFR endurance. At least two builders have gone with a full dual bus architecture to counter this, and lots of others are putting in two alternators and backup batteries for EFIS devices.