High Amperage Drain on Lead Acid Batteries 1700 watt kettle vs 400 watt coffee maker

[Mike90250]

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As for cable size as big as your wrist called a 750 MCM that cost $9 per foot.

Sir, you jest !! (good to hear your advice here) 300A @ 12V only requires 0000ga cable (0.46")

Of course, none of the inverters use heavy 300A cable inside them which is why you need a good insurance policy
And you need a gorilla to bend the cable to fit, along with the giant tool to crimp the ends onto the cable. And it's a very special inverter that has terminals of the proper size to connect that big wire to.


Here's some unnamed chart from the internet that supports my theory.

amp chart table.jpg

[Sunking]

Sir, you jest !! (good to hear your advice here) 300A @ 12V only requires 0000ga cable (0.46")

Not so much jest. While I understand the tables you posted and where it came from has little to do with any wiring you can use and comply with NEC. The tables are true for equipment manufactures chassis wiring and utility power transmission with complete disregard for voltage loss incurred at low 12 volts. That has nothing to do with residential power and lighting wiring. That comes from NEC Table 310.15(B) using 90 degree cable insulation would require a minim 350 MCM which still does not address any voltage loss at 12 volt distribution. So I may be guilty of stretching it a bit, the point is the insanity of using low voltage for high wattage loads. Not only is it incredible expensive, but extremely dangerous doing so with that much current. Joe DIY Home Owner does not have the tooling, training, or experience to terminate such sized conductors properly.

As you properly stated the first clue is something is not right is none of the 12 volt toy inverters sold can terminate a proper sized conductor or a massive surface area required. Example in any high current panels for commercial or industrial application using 350 amps would use Tongue type 2-hole terminals using Grade 5 3/8-inch hardware to secure it with proper torque.

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Here is a tip. If your application requires any wire to be larger than 6 AWG, your voltage is likely too low.

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