Wire gauge & grounding question

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Wire gauge & grounding question

Postby greasywheats » Wed Sep 13, 2006 12:09 am

I know this is a basic topic and has been beaten to death, but if I am running 2 berth lights, a FanTastic roof vent, a couple 12 v outlets (for a small 12v heater, and maybe 2 porch lights,...can i just simplify the whole math here and wire everything with 12 ga. copper stranded leaving the converter (WFCO) and 10 ga. from the shore power inlet to the converter? Rather than using 16 ga. here, 14 ga. there, etc....
Also, can I attach my ground wire from the ground bus of the WFCO converter to a stainless steel bolt that holds the floor to the frame as an effective ground?(i am not having any AC appliances/outlets onboard)
Thanks- its late and I'm feeling like a total dunce here as i start to wire my TD up!
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Postby madjack » Wed Sep 13, 2006 12:47 am

...a couple of thoughts...first, ground problems are probably the no1 problem when it comes to 12 vdc system(or maybe cheap fixtures...anyway)...we ran a seperate set of wires for each circuit ground and positive, soldering most all connections...we used 14 ga trailer cable for all 12vdc wiring split into 2 pairs...worked nicely...
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Postby asianflava » Wed Sep 13, 2006 12:56 am

Me too, simple 2 conductor wire to all circuits. They are all grounded at the fuse block. Besides, there isn't much metal to ground to so for simplicity, you may as well just run both wires to everything.
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Postby bledsoe3 » Wed Sep 13, 2006 2:04 am

GW, to answer your question on math, you can't go wrong using the larger wire everywhere. Better too big that too small. Just a little more cost per foot.
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Postby Sonetpro » Wed Sep 13, 2006 6:29 am

I have a WFCO converter myself. The ground bar is for AC ground only. If you ground it to the frame it won't provide you a return to the battery. I ran 2 wires also and ran all the negitives (battery grounds) to a copper bar and then a 6GA to the battery.
I agree with everybody else about the 12GA and 2 wire circuit. I ran nothing but 12GA in mine. Just remember to fuse the circuit according the the smallest wire on it. So if you have 12GA running to a light but the light has 16GA leads you need to fuse it to protect the 16GA leads.
I don't know what kind of heater you have. But you need to run heavy wire to it, It's going to pull alot of current.
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Postby Dale M. » Wed Sep 13, 2006 11:25 am

I would run a pair of same sized wires to each 12volt lamp or devices (fan or what ever) or power socket. I would provide a single ground bar along with fuse panel (close to battery). ALL ground connections should terminate on dedicated ground bar. Yes ground bar needs large gauge conductor to negative side of battery just like positive side of battery to fuse panel. IF you feel the need you can "bond" ground bar to metal trailer chassis, but its not necessary if you use single ground point concept. To make things really simple get some wire (appropriate gauge) that has two conductors bonded together so all power and ground runs are consistent. I like the concept of typical electric brake cable ( comes in seveal gauges) where there is a black and white condictor inside a single sheath, similar to romex for AC wiring...

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Postby jmtk » Wed Sep 13, 2006 2:03 pm

Sonetpro wrote:If you ground it to the frame it won't provide you a return to the battery. I ran 2 wires also and ran all the negitives (battery grounds) to a copper bar and then a 6GA to the battery.

OK, time to show my complete battery/wiring ignorance. What does the return to the battery provide? My current plan was to attempt using the tow vehicle's battery from a charge line, rather than have a dedicated battery on the teardrop itself (we have pretty low power requirements). I believe there is only a positive wire for the charge line, with no return wire to the negative of the tow vehicle's battery. How does one ground properly then? I was planning on running a ground wire to the trailer chassis, but is that not adequate?

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Postby Sonetpro » Wed Sep 13, 2006 2:36 pm

Jeanette,
DC Has a positive and a negative or a return. Although most people call the Negative a ground it is not a true ground it's a return to the battery. Most vehicles use the steel framework for the return to the battery, So everybody calls it the ground.
In my post earlier I was referring to the WFCO converter. I know that the AC and the DC are separate with this converter, so Grounding to the AC grounding block would not give a return to the battery.
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Postby Chuck Craven » Wed Sep 13, 2006 5:03 pm

Looks good!
Just use fuses or DC circuit breakers on each run.
Like 10 amp fuse for the lights and the fan, 10-amp fuse for each of the12v outlets.
Add up the current draw for each circuit and fuse it just a little more than what you will fully draw, with every thing running on that circuit!
You need to protect your 12v power battery, If something would short out the battery will pump more and more current in to the short until there is fire or a meltdown of the battery. That aint nice!! :cry:

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Postby madjack » Wed Sep 13, 2006 5:19 pm

J, the white wire on the trailer to car wiring harness is the ground wire...if you wish to run the camper on the charge (or if you even run a charge wire for charging) this ground wire should be the same gauge as the charge line...without a dedicated ground wire you are left with a less than adequate ground thru the ball hitch and coupler... I would recommend wiring the trailer for a battery if for nothing else but future options
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Postby Dale M. » Wed Sep 13, 2006 6:16 pm

JMTK wrote: My current plan was to attempt using the tow vehicle's battery from a charge line, rather than have a dedicated battery on the teardrop itself (we have pretty low power requirements).
Jeanette


You mean every time you leave tear behind for a days adventure you are going to disconnect tear from tow vehicle and go adventuring and every evening when you return you are going to "hook up" tear to tow vehicle so you can have power in tear... Sounds tiresome and impractical... Put a battery in tear and connect in a way when tear is "in tow", tear battery is charged, or IF you need to charge tear batter (camping in one place for long interval) you can "connect" to mother ship (tow vehicle) for charge session...OR install charger if you have shore power.

It will make TD life a lot simpler...

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Postby jmtk » Wed Sep 13, 2006 7:44 pm

Dale M. wrote:You mean every time you leave tear behind for a days adventure you are going to disconnect tear from tow vehicle and go adventuring and every evening when you return you are going to "hook up" tear to tow vehicle so you can have power in tear... Sounds tiresome and impractical...

Yup, that's the plan. My concern was to avoid excessive weight since we have a small tow vehicle. Since we've been tent camping for eons with no power (except for a lantern that runs off of D batteries), and rarely camp where there is shore power, the hope was that our low-power habits will continue when teardrop camping. If it does turn out to be "tiresome and impractical" or our power use is more than anticipated, I do have "plan B" in mind, which is to install a battery and charge it from the tow vehicle. My wiring will be done such that it will be able to accommodate the addition of a battery.

Thanks for your comments,

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Postby Dale M. » Wed Sep 13, 2006 10:06 pm

jmtk wrote:Yup, that's the plan. My concern was to avoid excessive weight since we have a small tow vehicle. Since we've been tent camping for eons with no power (except for a lantern that runs off of D batteries), and rarely camp where there is shore power, the hope was that our low-power habits will continue when teardrop camping. If it does turn out to be "tiresome and impractical" or our power use is more than anticipated, I do have "plan B" in mind, which is to install a battery and charge it from the tow vehicle. My wiring will be done such that it will be able to accommodate the addition of a battery.

Thanks for your comments,

Jeanette


Being a life long tent camper (well not actually as a kid my parents did have a small travel trailer) I can't wait to be able to complete my TD and PUT A BATTERY IN IT... I'm tired of flashlights and no air movement...

And if your tear runs down tow vehicle battery to where tow vehicle won't start what are you going to do...

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Postby jmtk » Thu Sep 14, 2006 9:39 am

Dale M. wrote:And if your tear runs down tow vehicle battery to where tow vehicle won't start what are you going to do...
Dale

Dale,

We always have jumper cables in our vehicles (and it sounds like you're never short on friendly visitors when you have a teardrop 8) ), and if we're camping in the middle of no where, we'd unplug or hit the master switch to be sure we don't accidently run it down. I thought about this whole battery/no battery issue a lot, and we may someday decide we want a dedicated battery, but wanted to try using the car one first before adding the weight and expense. We all have different camping styles - which is one of the reasons I loved the idea of a teardrop from the start - I can customize it to exactly fit my family's needs.

Jeanette

Sorry this turned into a hijack, GW!
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grounds, guages, batt's

Postby PcHistorian » Tue Feb 07, 2012 7:47 pm

http://tnttt.com/postin ... ly&t=11230

jmtk not a hijack, we're still talking grounds. I am considering a minor battery for just the lights, that is in normal life an emergency lighting battery. About the size of a motorcycle battery, but 12vdc and considered dry cell, I think. I'd rather have a 4 amp hour lithium, at 12v dc. Then on a separate circuit do the heavy amped system. I have a "jumper system from peak that is a piece of crap for actually jumping a battery with it, but for 12vdc deep charge at higher currents it might do ok. I have a 10 amp, self resetting breaker in the old glass-metal-capped-ends socket style, but open top holder, I wanted to use. I think it was from some power windows. That will breaker the 12vdc outlets (what's a real lighter draw? LOL)
I'm using romex 3wire (I surmise 14 ga) for my 110vac and 16ga. for 12vdc lighting, 14 ga for 12vdc outlets (says it is good for up to lighter's circuits...)
What I haven't' figured out yet was the fuse type for the lights. I have the socketed kind of holders for 110v items like stereos and stuff, that use the glass with metal end cap type fuses. I'll have to stock spares for one thing. lol I've considered bayonette type crimp females to use in conjunction with the larger but new style car fuses.

One thing I will say here. The core of the wire is always based on the strength for your current flow. 20 amps needs 12 ga, whether 12vdc or 110vac. The insulation is different though depending on your voltage and usage area. You need a higher voltage insulation if you are running 110vac, instead of 12vdc. You need gas resistant insulation if it is going to be under a car's hood, plus temperature resistance like if it hits the exhaust.

one other thing while we are talking grounds. I KNOW I should never trust the ball/hitch ground to carry a stead voltage, moving or still. Same with wire connecting to the frame as a ground wire, instead of running a ground (return/-12vdc,black) wire. Especially if the connection is outside where it will get kicked, rained on, possibly salted from the road and corrosion. But one thing I learned recently, it might be better to use a stainless steel bolt with separating washer to separate copper wires from steel frame, and it is DEFINITELY a must do if you have an aluminum frame and copper wires. (go through stainless steel bolt and washers to separate copper from aluminum.)
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