wgriswold wrote:
12 ga is higher than 10 ga. One chooses the gauge that is appropriate for the length and amperage of the application.
You have things backwards, wire Gauge sizes mean the OPPOSITE of what you would think they mean.
12 ga wire is a SMALLER Diameter than 10 GA wire.
SMALLER DIAMETER OF WIRE MEANS IT HANDLES LESS CURRENT.
12 ga wire handles LESS current than 10 Ga.
See chart
HERE which gives you the actual physical diameters of the wire gauges.
12 GA listed on that chart is 0.08080" in diameter.
10 GA listed on that chart is 0.10190" in diameter.
Last time I checked, .1" IS STILL LARGER than .08"..
For general use 12 Ga wire MUST be fused at no more than 20A.
10 Ga wire can be fused at no more than 30A.
If your RV has a battery fuse or breaker for 40A it MUST BE a minimum of 8 GA wire.
To be extremely clear, the ampacity above IS for INSULATED WIRE in free air.
Uninsulated wire in free air can withstand a higher current level, however that REALLY does not apply since it would really present a possible short circuit hazard if we stripped all of the insulation off of the wiring to get more ampacity..
