Small AC motors and Inverters
Disappointed that my ancient Mod Sine Wave inverter (140W cont, 200W surge) shuts down with a 120W coffee grinder. Works ok with the 400W (cont) MSW inverter built-into the truck, though a little ...
Forum Discussion
Chandalen wrote:
My chart shows 6ga single core copper as 95 amps rated. (you still should use 4ga single core for 100 amp)
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no..6ga is not rated for 100a
6ga is rated for 50amps
Where are you guys getting these numbers?
Looked around the web and most sites just talk about voltage drop.
Then found this calculator that takes into account insulation temp rating and other factors:
http://circuitwizard.bluesea.com/
It calculates the Ampacity (new to me, had to look it up on Wikipedia, but I think that's what you guys are referring to) as well as Voltage drop to determine cable and fuse size.
The wire you select must be large enough to meet both ampacity and voltage drop requirements.
So I enter 12V, 100A, 10ft (sum of + and -), 3%V drop, Fixed or Variable load (no difference in results), 105C insulation, 5 min duration and terminated at fuse.
And get 4ga recommended with the de-rated capacity of 136A.
If I knock the total cable length down to 8ft, get 6ga recommended with de-rated capacity of 102A.
So on the basis of this Circuit Wizard, and assuming (hopefully) 8ft of cable, 6ga would have a de-rated capacity of 102A and should be protected by a 100A fuse? Is this calculator wrong or am I entering data wrong or what?
And if that 100A fuse blows with my coffee grinder or hand blender, I can upgrade the cables to 8ft of 4ga and protect them with a 130A fuse (136A derated capacity according to the Circuit Wizard). Or more ...
