As I'm starting to put in wiring, simple question on 12v grounds. Does the neg, or ground as I understand, on each light-plug-acc, have to run back to the distribution panel, or can they be grounded right into the body metal-as in the roof beams?
12V Wiring
- Thread starter limmkr
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Best is round trips, same gauge same length wire.
If low current, very close so you can see the all-steel path, you can get away with it.
High currents, or crossing different chassis components, resistance issues likely to cause problems, if not now the down the road.
If low current, very close so you can see the all-steel path, you can get away with it.
High currents, or crossing different chassis components, resistance issues likely to cause problems, if not now the down the road.
Thanks, it's all open now, so might as well. One other issue, I bought 45 ft of 14 gauge at Ace Hardware for $32! I thought wow, this is gonna cost me alot. Then I go on Amazon and find 7 100' rolls for like $50, but it says is NOT AWG. Does that matter? I read a few comments and a few said, little thin, but works fine. I see some say 16 is even ok, so I hope I'm ok using this stuff.
I only use UL1426 type 3 tinned "boat cable"
http://www.bestboatwire.com sells Pace in bulk, every bit as good as Ancor, usually lots more expensive due to branding.
Sister co to genuinedealz, which does very reasonable crimp-terminated custom lengths.
Also Berkshire wire in Western MA, call for a local distributor, and East Penn Marine.
http://www.bestboatwire.com sells Pace in bulk, every bit as good as Ancor, usually lots more expensive due to branding.
Sister co to genuinedealz, which does very reasonable crimp-terminated custom lengths.
Also Berkshire wire in Western MA, call for a local distributor, and East Penn Marine.
You can use the vehicle body as a common ground for smaller loads, but you need to make sure the body itself is grounded with a couple of bonding straps to the frame of the vehicle.
If you want the return to a battery bank that you have added, then that battery bank needs to have the negative also bonded (with heavy gauge wire) to the frame and body. Don't assume the body metal is grounded properly, even if you get an indication that it is with a meter or test light.
If its a van, (you didnt say) and its a body-on-frame design, the body is probably on rubber or neoprene type body mounts. You need to bypass this with a couple of bonding straps.
Uni-body types like minivans might also need to be bonded, depending on the factory wiring harness. For safety, assume it also needs to be grounded to any subframe you can see under there.
For a just a couple of LEDs or power ports, its much easier to run a separate ground return for each item.
If you want the return to a battery bank that you have added, then that battery bank needs to have the negative also bonded (with heavy gauge wire) to the frame and body. Don't assume the body metal is grounded properly, even if you get an indication that it is with a meter or test light.
If its a van, (you didnt say) and its a body-on-frame design, the body is probably on rubber or neoprene type body mounts. You need to bypass this with a couple of bonding straps.
Uni-body types like minivans might also need to be bonded, depending on the factory wiring harness. For safety, assume it also needs to be grounded to any subframe you can see under there.
For a just a couple of LEDs or power ports, its much easier to run a separate ground return for each item.
regis101
Well-known member
I used 10awg marine wire throughout
For my 20amp system. Purchased via Amazon.
I chose to run both ways and not use the vehicle as a ground. I prefer to keep the entire secondary system separate from vehicle electrics
For my 20amp system. Purchased via Amazon.
I chose to run both ways and not use the vehicle as a ground. I prefer to keep the entire secondary system separate from vehicle electrics
Wow regis101, are you talking for your 12V? The RV guy suggested 12 AWG for a 110v 15 and 20amp wiring, I figured that was over kill for 12v. I will keep it all separate as well. Thanks for the battery grounding tip. I think I missed that in my diagram!
Trebor English
Well-known member
limmkr said:
With 20 amp current, 120 volt or 12 volt, you need 12 AWG. With 12 volt circuits the currents are generally about 10 times as much as with 120 volt circuits. That makes voltage drop due to cable resistance a problem that isn't normally noticed with 120 volt circuits.
regis101
Well-known member
The wiring sticky at the top can offer info. The 20a Renogy kit I bought came with #8 tray cable and #10 panel cables. Go figure. My past experience with DC voltages is fine strand cables and larger gauge. YMMV
Plus with larger gauge per given amperage can help control surges and spikes and shorts but that's just me
Plus with larger gauge per given amperage can help control surges and spikes and shorts but that's just me
Yes, low voltage **always** means much heavier gauge wiring.
> I had the Rv guy tell me not to use tin type.
Maybe he meant to use copper, "tinned" just means copper treated against corrosion. Marine grade, as spec'd above, is the good stuff if you want it to last.
Sure you can just use it where you think moisture and road gunk will be a problem, but just getting a few different gauges in bulk cuts down on the premium, and feeling secure is IMO worth it.
If you don't need much then you probably won't be investing in proper crimpers either, so best to just have genuinedealz do them to order for you.
> I had the Rv guy tell me not to use tin type.
Maybe he meant to use copper, "tinned" just means copper treated against corrosion. Marine grade, as spec'd above, is the good stuff if you want it to last.
Sure you can just use it where you think moisture and road gunk will be a problem, but just getting a few different gauges in bulk cuts down on the premium, and feeling secure is IMO worth it.
If you don't need much then you probably won't be investing in proper crimpers either, so best to just have genuinedealz do them to order for you.
highdesertranger
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for 12v use only auto or marine wire, marine is better. DO NOT USE HOUSEHOLD WIRE. for 120v use marine stranded wire do not use solid wire for anything. highdesertranger
regis101 said:
This is good practice but the vehicle electrical system on modern era vehicles is already separated from body and chassis ground on most, but not all, components.
So essentially, if you do choose to use the body and frame as the ground return in your secondary system, you are still separated from most of the vehicle systems.
Spaceman Spiff
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limmkr said:
With 110 AC you spec your wire for ampacity (the maximum amps a wire gauge can safely carry). With 12V DC you spec your wire for voltage drop. Voltage drop is not a very big issue with AC, one is more worried about heating the wire to melting point (and starting a fire) by pushing too many amps through it.
Always use automotive or marine wire. Stranded wire is more flexible, is more resistant to breakage due to vibration, and the wire insulation is made to withstand abrasion, heat and chemicals found in automobiles. Marine wire is additionally tinned for corrosion resistance.
-- Spiff
Scott7022
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The confusion is the difference between best practices and general practice. Don't worry about it. When discussing electrical systems you can get caught up in the language and examples and lexicon. I read a great thread on Expedition Forums about this term voltage drop. Three very intelligent and professional engineer types. It would have gotten killed on this forum as it got very heated. Each was looking at complex systems, far more than here and coming at the solutions from different directions. It was like watching Bob, from Bob's solar page debate with someone as smart as Sternwake here and another top notch professional from the marine industry.
First and foremost, wire is cheap. I know it doesn't look that way now. But after everything is in and built and happy day camping, saving a a dime or two will cost you a C note or three. If/when you have an issue. House wire is designed for foundation houses and those only move in California. Solid wires break when they wiggle and they can break quickly with the right frequency wiggle. Jiggly, Wiggly Club=Good, Van/RV= Not Good. Yes some RV's do it. Because it is cheaper and they won't have to fix it. You will.
Second. Think of wire like a water hose. From power BUCKET you have high pressure low volume or Low pressure high volume. Pressure is voltage and volume is amperage. Each of these hoses have to be different is sizes. High pressure low volume smaller and low pressure high volume larger. 120 is high pressure and 12 volt is low pressure. I hope that helps.
Stranded copper wire is the best and will last the life of your truck/rig. Read, done right, you will only do it and spend money on it one time.
The links John posted are good for cheap know quality wire. You can go the Amazon route and save some bucks but you really don't know what your getting from bulk international distributors and for most builds the savings is negligible. This is from a risk/reward viewpoint.
The BlueSea marine website has all sorts of calculators for sizing wire. Sizing wire is important. Failure in this area will start fires, smoke, and kill you. No dramatic sparks and jiggling electrocution. Just a wire that gets hot and smolders, doesn't pull enough current to trip a breaker, and gasses you with toxic materials as you dream.
Grounding. Grounding back is a good idea if anything on the circuits have a speaker. The differences in resistance can introduce a hum, or ground loop. This ground loop is like a ghost and it can effect all sorts of equipment you may plug into the build once it is done. This happens when the measured Ohms of resistance have a difference between the battery ground and circuit ground. Usually it has to be a significant difference. But Usually sucks as a word for design application. Upgrading factory grounds are good. Like a yard of cable (big wire 1 gauge). Then ten feet of four gauge from your circuit ground to the same ground bolt the battery uses. Not an expensive outlay. Personally I use the same gauge cable from the circuit that I used on the battery but this is unnecessary and probably stupid.
Everything running on 12 volt should be checked on the wire size calculator. So other than your inverter find the biggest gauge wire you'll need. Buy two spools of stranded marine grade (red and Black) as it is cheaper in bulk and use that gauge wire for everything 12 volt. If you need to add an extra cigarette plug for the new ARB later you'll be fine. If you use different sizes then you have to remember find, tap and... PITA!!!
120v should be limited in our types of builds and if you have left over 12 volt wire going bigger to an outlet is not a problem. The only issue will be the new style of receptacles that have cut and push connections. Not good for an RV but probably the reason the guy said 12/2. Without seeing the bunny it is difficult to get on the same page to cook it, right? Make sure the Battery to the inverter connection CABLES are oversized. It should be as short a distance as you can design so no big expense. If you change your batteries later you won't have to replace these cables. Not to confuse you but when Lithium gets cheap and Hybrid inverters do as well you can leave the original cables you bought and just upgrade the other stuff. So if it calls for twenty inches of 1 gauge cable put in 3 gauge, the difference in cost between 1 and 3 for twenty inches is nothing. Then later if you upgrade a little Honda 1000 plugged into your shore power will let you run the big A/C (with a soft start) as the Hybrid Inverter can switch and pull current from the battery bank and help out the little red Honda until it cycles off the compressor and then charge the batteries. In an oversimplified example. But I don't want to get yelled at for telling someone what to do by just saying spend 29 bucks on 3 gauge instead of 19 bucks on 1 gauge.
If you are confused that is fine. This stuff does get close to rocket science. I am trying to keep it lite so don't think I am being condescending. I've recently pissed off a couple of sensitive types so just being careful. If you need more help or specific help ask away here or PM and I will help you. I will also show you the models and certification standards and links as I have the websites saved as I went back and forth for two years designing what I needed.
First and foremost, wire is cheap. I know it doesn't look that way now. But after everything is in and built and happy day camping, saving a a dime or two will cost you a C note or three. If/when you have an issue. House wire is designed for foundation houses and those only move in California. Solid wires break when they wiggle and they can break quickly with the right frequency wiggle. Jiggly, Wiggly Club=Good, Van/RV= Not Good. Yes some RV's do it. Because it is cheaper and they won't have to fix it. You will.
Second. Think of wire like a water hose. From power BUCKET you have high pressure low volume or Low pressure high volume. Pressure is voltage and volume is amperage. Each of these hoses have to be different is sizes. High pressure low volume smaller and low pressure high volume larger. 120 is high pressure and 12 volt is low pressure. I hope that helps.
Stranded copper wire is the best and will last the life of your truck/rig. Read, done right, you will only do it and spend money on it one time.
The links John posted are good for cheap know quality wire. You can go the Amazon route and save some bucks but you really don't know what your getting from bulk international distributors and for most builds the savings is negligible. This is from a risk/reward viewpoint.
The BlueSea marine website has all sorts of calculators for sizing wire. Sizing wire is important. Failure in this area will start fires, smoke, and kill you. No dramatic sparks and jiggling electrocution. Just a wire that gets hot and smolders, doesn't pull enough current to trip a breaker, and gasses you with toxic materials as you dream.
Grounding. Grounding back is a good idea if anything on the circuits have a speaker. The differences in resistance can introduce a hum, or ground loop. This ground loop is like a ghost and it can effect all sorts of equipment you may plug into the build once it is done. This happens when the measured Ohms of resistance have a difference between the battery ground and circuit ground. Usually it has to be a significant difference. But Usually sucks as a word for design application. Upgrading factory grounds are good. Like a yard of cable (big wire 1 gauge). Then ten feet of four gauge from your circuit ground to the same ground bolt the battery uses. Not an expensive outlay. Personally I use the same gauge cable from the circuit that I used on the battery but this is unnecessary and probably stupid.
Everything running on 12 volt should be checked on the wire size calculator. So other than your inverter find the biggest gauge wire you'll need. Buy two spools of stranded marine grade (red and Black) as it is cheaper in bulk and use that gauge wire for everything 12 volt. If you need to add an extra cigarette plug for the new ARB later you'll be fine. If you use different sizes then you have to remember find, tap and... PITA!!!
120v should be limited in our types of builds and if you have left over 12 volt wire going bigger to an outlet is not a problem. The only issue will be the new style of receptacles that have cut and push connections. Not good for an RV but probably the reason the guy said 12/2. Without seeing the bunny it is difficult to get on the same page to cook it, right? Make sure the Battery to the inverter connection CABLES are oversized. It should be as short a distance as you can design so no big expense. If you change your batteries later you won't have to replace these cables. Not to confuse you but when Lithium gets cheap and Hybrid inverters do as well you can leave the original cables you bought and just upgrade the other stuff. So if it calls for twenty inches of 1 gauge cable put in 3 gauge, the difference in cost between 1 and 3 for twenty inches is nothing. Then later if you upgrade a little Honda 1000 plugged into your shore power will let you run the big A/C (with a soft start) as the Hybrid Inverter can switch and pull current from the battery bank and help out the little red Honda until it cycles off the compressor and then charge the batteries. In an oversimplified example. But I don't want to get yelled at for telling someone what to do by just saying spend 29 bucks on 3 gauge instead of 19 bucks on 1 gauge.
If you are confused that is fine. This stuff does get close to rocket science. I am trying to keep it lite so don't think I am being condescending. I've recently pissed off a couple of sensitive types so just being careful. If you need more help or specific help ask away here or PM and I will help you. I will also show you the models and certification standards and links as I have the websites saved as I went back and forth for two years designing what I needed.
Simplified. Solid wire from Home Depot type stores should not be used in a vehicle. The stranded wire they sell is also not easy to work with. Go premium with marine grade from a USA supplier. Genuinedealz.com or BayMarineSupply.com are the ones with the best prices and quality stuff. Automotive grade will work better than BigBoxStore. But automotive is sometimes SAE sizes, I recomend AWG sizes.
Yes Alan at Bay Marine in San Digo is a trustworthy supplier, low pricing like PKSYS but personal touch service and advice.
I wasn't aware he sold bulk wire.
Buy from his website or otherwise directly, rather than cutting his margin via his Amazon or eBay shops.
I wasn't aware he sold bulk wire.
Buy from his website or otherwise directly, rather than cutting his margin via his Amazon or eBay shops.
I used jacketed trailer cable (also called jacketed brake cable) for the lighter duty 12v runs in my builds. You can buy it in 2 conductor up to 7 conductor.
It's tough, resistant to oil, grease, acid, weather, abrasion, etc.
And easy to work with.
It's tough, resistant to oil, grease, acid, weather, abrasion, etc.
And easy to work with.
Scott7022 , your 2nd point about water bucket as POWER is one of the best I've ever heard. ... I've only been derailed by trying to FULLY understand amps vs volts for almost 60 years! Just when I think I got it, I don't.
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