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Grounding to frame or battery for fridge and compressor in bed.

Shawnu22

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This is a good topic with some different ideas on what to do. I hope we can get more input from those in the know. I plan to run my Dometic CFX75 fridge, an inverter and a compressor so this is all very interesting to me. I am no electrician but I do enjoy learning things like this.
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Radio Guy

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So this is what I was asking earlier. If I were to run all the way back to the battery I'd need to double the length, which would mean 6 AWG would be the way to go. If I ran a ground to nearby frame that was 2' instead of 15' I'd need to calc 17' voltage drop.
Yes, unless mounting the fridge provides an electrical ground at the mounting point you would have a double run of wire back to the battery. Or in this case the 2' wire to the frame would share the ground current with the grounded mounting point.
 

ShadowsPapa

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That’s good to know! The max amp draw the viair lists is 23 amps. So you’re thinking I’m good keeping the 10 awg for that span of 15’ or so?
Max is usually the surge draw as in when a motor or compressor starts. The continuous draw is usually much less than that.

I had to size a high-end dual-conversion UPS for my wife's quilting and embroidery equipment - I went by the max values and then went down a bit from there. Now monitoring the whole system, one of her machines that said "max amps 5.3" pulls 1.7 when it's running full load.
Compressors are different - they will pull a fair amount after started while running - but still your max is the highest, operating it will be less than that for sure.
If it says 23 - you can count on the running pull to be under 20.
 
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Eventyr_JT

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@Radio Guy’s recommendations follow my research. I plan on running two 40A circuits to the bed near the knockout for the 120v outlet. I measured 22 feet from where my breakers will be mounted at the battery and 20 feet to the grounding terminal near the battery.
Using the wire calculator with 2% voltage drop, my wires will need to be #2 AWG. Sounds like a huge wire, but I’d rather oversize my wire than burn down my Jeep.
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