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Old 09-17-2018, 08:32 PM   #1
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wiring fridge ground to frame?

Hello. I made the mistake of putting my fridge far away from my battery and have to run 6 gauge wire and would like to avoid running it both ways. Has anyone run their DC fridge to the frame for ground, rather than the battery? It is a NovaKool 5812. Can anyone explain what the difference would be in terms of performance or protection of the appliance?

Thanks.
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Old 09-17-2018, 08:48 PM   #2
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All of my 12v grounds use the bus body and frame for returns. The battery ground terminal goes directly to the frame/body and all the ground wires from the 12v applications go directly to the frame/body wherever they are. A word of caution, however, be sure the ground attachments are kept clean, dry and secures or you will end up with high resistance shorts capable of heating conductors to the point of their ignihting.
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Old 09-17-2018, 08:52 PM   #3
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I never rely on chassis return for any important / expensive nor high current load devices.
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Old 09-17-2018, 08:58 PM   #4
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I respect your choice but would like to hear (electrically speaking) why.
Thanks, Jack
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Old 09-17-2018, 09:06 PM   #5
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the spaghetti system -- wiring and angry pixies

Here is how I look at it. When we use the frame, body, chassis as the ground framework, we are setting up the lot to have problems. We also turn the corrosion monster on.

Other things, like aeroplanes do not, to my knowledge, use the chassis as a ground network. Many times the chassis/body/frame grounds are the source of the problems with electrical systems in automobiles.

I am running grounds to terminal strips and the battery and alternator will also be grounded to the same terminal strip. This will be extra work in the short term in exchange for long term lack of problems.

I will give you an example. A ground wire starts at the drivers top in the roof runs across the roof in front to the passenger side, drops down to the skirt on the passenger side, runs to the rear along the skirt, up the passenger side at the rear, across to the drivers side along the roof, down to the skirt on the drivers side, along the drivers side skirt to the engine bay, terminal strip. all clearance, running, stop, turn, lights will use the same ground. I also have zinc pieces from the boat world, to attach to the body and will run chassis/ body ground to the planet earth. These are rubber strips about an inch wide that drag on the ground. Wires embedded in the rubber strips.

I think in the end it boils down to what is thought, by some, as a "better practice"

Kind of like a surgeon that uses a check list, and a surgeon that has a checklist but doesn't really use it, and the surgeon that does not use check lists. Mistakes will happen, some less often than others. I am sorry if I rambled on here.

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Old 09-17-2018, 09:11 PM   #6
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taking a risk

Sounds like you are all saying the same thing, i.e. you are taking a risk by running separate grounds. Probably worth it for my toilet fan, but not my $1400 fridge.

So any of you smart folks know about inline fuses? I can't find a 6 gauge/15 amp inline fuse. Can I run say a 10 gauge wire inline fuse 1 foot from battery and splice to the 6 gauge? Fridge requires 15 amp fuse, my 43 feet requires 6 gauge wire. Also some wire calculators say you have to count BOTH directions (i.e. ground wire too), but the fridge manual says only count distance to battery?

Thanks.
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Old 09-17-2018, 09:33 PM   #7
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do not use inline fuse... use a fuse block terminate wire with ring or hook terminal, to fuse block, then fuse, then wire to battery..... much larger than than the fridge wire.
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Old 09-17-2018, 09:45 PM   #8
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I have an AC/DC power center, but the DC fuse block won't take 6 gauge wire - for some reason is very tiny - too tiny to even use a ring or hook. Can I run a 10 gauge from a separate buss to the fuse panel with my 6 gauge on the other side of this buss? Fuse panel will be wired directly to battery.
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Old 09-17-2018, 10:00 PM   #9
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Not just corrosion over time, modern builds often just don't have good low-resistance paths fresh off the factory floor.

But yes even on old school frame rails, resistance can build over time.

Low amp non-critical cheap gizmos, go for it if you like.

In fact do what you like full stop, just giving my advice.
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Old 09-17-2018, 10:07 PM   #10
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short answer don't do it. I will elaborate if you wish. Time for new fuse block do not replace what you have just going to add one. did not think of this till now... use circuit breaker like this one.
Box-Style Circuit Breakers Series - Circuit Breakers from Other Products and Accessories - Littelfuse

the screw for the power wires are 10-32 for all of them up to 40 amp..... so the ring terminal for a 10-32 properly crimped will be fine for 15 amps

In my mental picture a bus bar has one big honkin cable attatched and that goes to the power feeding the bus bar. all the other cables on the bus bar are much smaller than the big honkin cable. Same set up for grounding.
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Old 09-17-2018, 10:49 PM   #11
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I don't disagree with any of that in principle. However, in practice on a converted school bus that may last say 10 years it seems to make about as much sense as using land mines to rid your property of coyotes. Sure it works but every body just remembers the guy who used land mines to rid his property of coyotes. It ain't rocket science but it sure is overkill.
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Old 09-17-2018, 11:45 PM   #12
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Oh, for grounds I use a copper plate (with some special goo) bolted to the seat rail. It all depends on how many amps. 30 amps plus, done this way should work. Use a IR temp gauge to shoot those points under full load. If you worry about line loss do a home run on the ground lead.
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Old 09-18-2018, 08:45 AM   #13
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Without question everyone here is far wiser electronically than I am...but...as best I can recall, every vehicle I have owned in the last 60 or so years (old cars, new cars, trucks, sports cars, motorcycles, RV's, buses, etc. ) used the chassis as ground.


Simple guy that I am, I will probably go that route.
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Old 09-18-2018, 12:51 PM   #14
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grounding to frame

Thank you all for your responses. Guess I will go to battery for fridge ground, manufacturer emailed me back that only distance to battery needs to be counted. Can use inline circuit breaker (they recommend don't require), but they do require a fuse. If I understand advice, if I get a buss, can run battery to this then to my power panel, and from buss directly to fridge (with breaker and fuse). They call for direct battery hookup, but then one has to use an inline fuse. I have a minimalist bus and the fridge is my biggest draw so hate to get another fuse box - why are inline ones a bad idea, provided I can get a 6/15 setup?

I don't actually have a huge wire from battery to panel, used a gauge calculator and based on expected draw only a 10 gauge was required so was going to use 8 gauge as my largest pull will be under 50 amps. Guess it couldn't hurt to go bigger though so will rethink that for both the charger and battery.

This DC stuff is the hardest to figure out yet.
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Old 09-18-2018, 02:44 PM   #15
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Take a look at ANL style fuses and holders, will probably have some options in your size range. They're available up to quite large sizes.

Edit, looks like they start at about 35a. You're going to want to size it to protect your wiring, not necessarily for the expected load. Blue Sea has a good explanation here:

https://www.bluesea.com/support/arti...t_Installation
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Old 09-18-2018, 02:52 PM   #16
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I may not be looking at the right spec's.......

What I found online says that the fridge draws 4.4 amps at 12 volts.

I am a big fan of oversize conductors but is 6 gauge really called for?
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Old 09-18-2018, 04:55 PM   #17
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Depends on distance and desired voltage drop.

I only stock three rolls so always round up.
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Old 09-19-2018, 10:36 AM   #18
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Quote:
Originally Posted by john61ct View Post
Depends on distance and desired voltage drop.

.
No doubt.

With a 4.4amp load at 13.8volts you can run 158' and stay under 2% voltage drop.

https://www.wirebarn.com/Wire-Calculator-_ep_41.html
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