Calculate Cable thickness depending upon current

[Vindhyachal.takniki]

1. I have bought a low cost ac-dc charger from China. It is from 220Vac/50Hz to 54.6Vdc/20V charger.
It dont have any manual or wiring diagram with it. It has five connections: Line,Netrual & earth on input. On output it has thick terminals for V+ & Ground.

2. At output 54.6Vdc/20A, wattage is 1092W. How to calculate what is the exact wire & its size I should use. I have to charge a battery, so have to make red & black wire with clips myself. But what wire size(AWG) should I buy.

3. Similarly at input, it is 220Vac/50hz. Output is 1092W, consider charger is 75% efficient (though there is no manual, I am cosindering this as worst case), power at input will be: 1092W/0.75 = 1456W.
For this which wire should I use?

Is there any calculator to calculate?


1. For dc, I found below:
http://www.solar-wind.co.uk/cable-sizing-DC-cables.html


2. For ac & dc
http://www.powerstream.com/Wire_Size.htm
But this is not for exact dc. need to select AWG first.


Got idea from these two. But any more info on this also?

[ConKbot]

For the mains, you have the wattage figured out correctly, and you're looking at 6-7A if it was a resistive load. But with 75 percent efficiency I'm guessing the PFC was skimped on, so figure a PF of 0.6, so 7A/0.6=11.6A I'd run 14AWG or 1.75/2.0 mm2 wire for that.

As far as the DC output, on low voltage high current outputs, usually voltage loss is an issue before wire heating. If you allow a 1V drop, (About 2 percent in this case)  you need to keep your wires under 50 miliohms (1V/20A) so 25 milliohms each for red and black.  Use a chart to figure out your minimum wire size (i.e. http://www.powerstream.com/Wire_Size.htm ), and then use resistance to figure out how big of a cable you need for longer runs. I.e. A 14 awg cable would hit 0.025 ohms at around 3 meters, so use it for anything under 3m.  10AWG/5.25mm2 would work for about 7.5 meters.

For mains, generally I use 18AWG for everything under 10A, 14 AWG for under 15A and 12AWG for under 20. Your mains cord has to be beefy enough to not burst into flames when its overloaded and waiting for the breaker to trip. As you can see on that table 18 AWG is fine with 16A so the usual US/EU breakers will protect the lead fine.  If you live on an island where numpties decided a 32A outlet for all household appliances is reasonable then a fused plug is advised.