Again, I'm confused?????

[BPFox]

The nice thing about this forum it we get to present different ideas. The bottom line here is that there is more than one way to do things right. I guess a lot would depend on the layout of a given trailer. Based on what I have read here there are plenty of different ideas on how to lay things out and what works best. For me, most of my electrical is going to be in the back of the trailer as that is where the need is. I will be running two inverters, one in the back that will be hard wired to the batteries. The other one will be in the front of the trailer to run the "entertainment center". This device will need a standard 12v outlet. Since I will need to run two 12 ga wires to the front (one positive and one negative) and those wires will run right past my cabin lights, why not switch the negative wire to 10 ga and eliminate two wires. Running multiple negative wires side by side just doesn't make sense to me. If you folks like it, no problem, for me it's just a waste of good wire. As for problems down the road I have a very simple approach to things like this. Do it once, do it right, never worry about it again.

[Alphacarina]

I will be running two inverters, one in the back that will be hard wired to the batteries. The other one will be in the front of the trailer to run the "entertainment center". This device will need a standard 12v outlet. Since I will need to run two 12 ga wires to the front (one positive and one negative) and those wires will run right past my cabin lights, why not switch the negative wire to 10 ga and eliminate two wires. Running multiple negative wires side by side just doesn't make sense to me

So long as the wires are adequately sized, that would certainly work and it will be safe as well . . . . but it's not the way I would do it. Likely you're not really saving any money or wire either, because the difference in weight and cost of a 10 gauge wire compared to a 12 gauge wire is likely about the same as using a 12 gauge wire along with a dedicated 16 gauge wire as a ground for your cabin lights . . . . you might actually be using more copper than if you had run a dedicated wire for your cabin lights gound

Using the ground wire of a high current device (the inverter) to ground the cabin lights will have your cabin lights 'flickering' when the inverter is in use and drawing current through it's gound wire - The higher the load on the inveter, the dimmer the cabin lights and if the inverter load varies, so will the intensity of the cabin lighting. While it may be safe, it's still not the advisable way to go

Another disadvantage is that later on down the road, if you ever experience electrical problems of any kind it will be much harder to troubleshoot them because you don't have all of the connections available in one place . . . . you have ground connections scattered all over the trailer - That doesn't strike me as doing it 'right'

On a DIY project, like a teardrop trailer, the builder is free to engineer most things any way he likes and since your method is safe so far as I can tell, there's nothing wrong with you using it but I would hesitate to recommend to anyone else to just daisy chain their ground wires together without carefully examining what the loads are, which ones will be running at the same time and what the various voltage drops are likely to be.

As a general rule, you shouldn't share the ground wire of any high current device (like an inverter) with other circuits, like lighting or fans. For the average guy who can't or doesn't care to go through all of evaluation necessary, individual grounds are the safe and predictable way to go . . . . and I would never go so far as to tell anyone that they are 'unnecessary' or a waste of money or wire

But . . . . we all get to do it pretty much any way we like, so it's all good

Don

[BPFox]

I understand what you are saying, but I guess I don't consider a 375 watt inverter as a "high current device". Today I did a mock up (on the bench) to test your theory about lights dimming. Sorry, but I must report no flicker at all. Not that I'm bragging, but in 30 plus years of wiring DC circuits I have never had splice fail. (Now that I have said this, I expect a boat load of failures tomorrow!) I guess for me, I just like the clean look of no visable ground wires. I just like my wiring to be neat, clean, and functional. I do, however, appreciate other points of view. Peace.

[Alphacarina]

I understand what you are saying, but I guess I don't consider a 375 watt inverter as a "high current device". Today I did a mock up (on the bench) to test your theory about lights dimming. Sorry, but I must report no flicker at all

Operating at maximum, your inverter will draw over 30 amps from your battery - That's a fairly 'high current' device by most anyone's standard

Whether or not your lights flicker will depend on the load on the inverter - When it's drawing 25 amps, the voltage drop in a 10 foot piece of 10 gauge wire will certainly be measurable . . . . and it should be visible as well

As I said, it sounds safe . . . . buy I would still object to your advising others that their dedicated grounds are 'a waste of time'

Don

[Sonetpro]

All of my grounds go to a copper buss bar with a 6ga wire going to the battery Neg. I also have a single pair of 10ga going to the front of the cabin with 4 lights on it.
I can't imagine an entertainment center in a tear that would come close to maxing out a 375 watt inverter. I don't think my home entertainment center could do that.
The biggest power draw on my inverter is the TV/DVD and it only draws 4 amps.
BP if you work on DC circuits I am sure you have an amp meter and and have measured it so the circuit will be safe.

There is no right and wrong.
There is just your way or my way.

[BPFox]

Sonetpro you got it right. My "entertainment center" consists of a 13" TV with a built in DVD player. That whole "entertainment center" thing was kind of tongue in cheek description. Sure the inverter is capable of producing 375 watts of power, but I can't even immagine it ever doing it. As far as power inverters go, it's a pretty small one. The draw is going to be so insignificant that 10 ga wire is almost overkill. That said, I have plenty of 10 ga on hand so what the heck, I might just as well use it. As far as home runs with dedicated negatives, knock your socks off. It's all good, just offering up a different approach. In reality, there will be very few times when the "ground" is shared at all. The TV is there for the most part to "entertain" during periods of bad weather. This would happen mostly during the day when the lights won't be on. At night, if the TV is on, the lights won't need to be. If the lights are on that means somebody is reading a book. Hard to read and watch TV at the same time. Combine that with the fact that it is a pretty rare camping trip when I'm not at a campground without electric hook ups and, well, you get the idea.

Side note to Don, I never said running dedicated grounds was a waste of time. I said it was a waste of wire. No amount of time working on one's own homebuilt trailer could ever be considered a waste of time no matter how many electical wires you choose to run. Peace.

[bobhenry]

The only reason I ran individual grounds to each 12 v tap was to avoid a gross blackout. By daisey chaining all the grounds you only have to lose one connection to be totally in the dark. In the case of a direct short (AS I HAD) I only needed to remove 1 ground to isolate the problem without affecting the other circuits. My 2 cents worth.

[BPFox]

The only reason I ran individual grounds to each 12 v tap was to avoid a gross blackout. By daisey chaining all the grounds you only have to lose one connection to be totally in the dark. In the case of a direct short (AS I HAD) I only needed to remove 1 ground to isolate the problem without affecting the other circuits. My 2 cents worth.

Actually, you could take a pair of wire cutters and cut any one of my pigtails and it would have no effect on the other loads. Think of my single wire system the same way you would look at using the frame as a "ground". If one light has a bad "ground" to the frame, only that light is effected. The only difference is by using a copper wire and proper connecting methods and the system is pretty much fail safe. I don't consider this method to be "daisy chain" as the single wire is never cut or broken. Think of it this way. Instead of running negative wires from every load back to a common buss bar, I just bring the buss bar to the load. With my system each load still had a negative wire but it's only 6" long. From my perspective it's just a cleaner way to do it. Less wires to do the same job and it looks better. You never see the negative wire. It's still there doing it's job (just like the frame on your tow vehicle) you just don't have to deal with all of those extra wires coming into clutter up your electric panel. But like I said before, home runs are cool. To each his own. Peace.

PS: I love your roof grab bar idea and the "see through roof" is killer.