current caclulation

[prkaye]

I'm working out my avionics current load. The GTX327 says maximum power input of 20Watts. So my naive calculation of 20W/12V < 2Amps means this this device will never draw more than 2 amps. Have I done this correctly?

[RV6_flyer]

Originally Posted by prkaye

I'm working out my avionics current load. The GTX327 says maximum power input of 20Watts. So my naive calculation of 20W/12V < 2Amps means this this device will never draw more than 2 amps. Have I done this correctly?

P = IV (P = Power is Watts, I = current in Amps, V = Volts)

20 W / 12 v = 1.6666 Amps

A two (2) amp CB or fuse will work. Make sure that the wire is the correct size (or larger) for the fuse or CB.

Your calculations are correct.

[sjjonesnz]

FYI, the GTX327 installation manual calls for a 3A breaker...

[Greg Arehart]

And remember that the breaker is not designed to protect the avionics, but to protect the wiring.

greg

[Crossbow]

Originally Posted by prkaye

I'm working out my avionics current load. The GTX327 says maximum power input of 20Watts. So my naive calculation of 20W/12V < 2Amps means this this device will never draw more than 2 amps. Have I done this correctly?

Well, since you are asking for opinions, I can think of three additional things to consider:

One, as was pointed out, the 327 manual specifies a 3A breaker, so you might want to stick with that.

Second, while this might not be a factor since the wiring run will be relatively short between the 327 and the power source. However, I think it would be good practice to account for the voltage drop in the wiring as well.

Third, as was also pointed out, the fuse/breaker is there to protect the wiring, not the device.

I hope this helps!