2/0 or 4/0 for 3000W inverter

[herman2021]

I see many wiring diagrams (e.g. explorist.life) that show 4/0 cable to the inverter when upgrading from a 2000W inverter to a 3000W inverter. 2/0 I believe can handle up to 400amps. Is 4/0 really necessary? The reason I ask is I will be temporarily using a 2000W inverter that will not be wired in to the panel and 2000W and 2/0 is overkill even for that. But the long-term plan is to wire in a 3000W inverter to the panel. Even then, I don't see myself running the AC units on the battery when boondocking. My BattleBorn GC3 270Ah battery is rated for 300amps. Just trying to figure out what would be drawing all these amps that would require 4/0 cable.

[xrated]

I'm not sure where you came up with 2/0 being able to handle 400 amps, but that is dead wrong. You are looking at a 3000 Watt inverter being fed by 12volts so doing the math on that part of it....Watts, divided by volts will equal amps....so 3000 divided by 12V = 250 amps. So for 60 degree C rated cable you would need 350 MCM size cable. For 75 C rated cable you would need 250 MCM.....and for 90 C rated cable you would need 4/0. If you buy aluminum cable instead of copper, those cable sizes are even bigger. Ignore the right half of the chart.....that is for aluminum cable

https://www.usawire-cable.com/pdf/nec-ampacities.pdf

[herman2021]

Thanks. That makes more sense. I was told 400amps by someone but he seemed a little unsure so glad I asked. I'll install 4/0 and call it a day.

[cookinwitdiesel]

Thanks. That makes more sense. I was told 400amps by someone but he seemed a little unsure so glad I asked. I'll install 4/0 and call it a day.

I used 4/0 for all of my inverter and battery cabling. That is the high draw stuff, not worth cutting corners. Other DC loads are fed by 6awg or 2awg as appropriate.