Originally Posted by John Linck
Conductor size over such short distances makes very little difference at these low amperages. Just use #12 wire and you will be fine. Line losses pale in comparison to poor orientation, shading losses or lack of LED lights
Got to thinking about my statements above. They apply to most 12 volt circuits in your trailer, but not to a large inverter if you have one. These 1000-3000 watt beasts can really suck the battery
amps. Most Scamp
circuits do well with 10 amp (or less) fuses. Some large inverters need 100 amps or more. Now we are talking large heavy copper wires and very short runs. Follow the manufacturer's instruction and be careful with online forum arm chair advice.
OTOH if you have a small inverter (<100 watts) for your phone/laptop charging a 10 amp fused circuit is probably enough. Remember, Volts X Amps = Watts so a 100 watt 12 volt inverter will draw as much as 8.5 amps, usually less.
Good camping, john