grounding

Thanks for the input always greatly appreciated. Electric is not my strong point so have too ask. I would hate to plug in my RV and have the closest nuclear power plant blow up. :B

My setup is exactly like Bobbo's.

Don't get too held up on the precise topology that the wiring diagrams show. It just boils down to the positive lead going to the positive DC bus and the negative to the negative, which is also the chassis ground. Where the chassis ground connection(s) are made on the negative battery line is somewhat immaterial, provided of course that the wiring is everywhere of sufficient capacity for the current that it could need to carry.

As the manual mentions, don't omit the safety ground from the chassis of the converter to the vehicle chassis. (That's there, as I understand things, in case there's a fault in the negative output line; without it, the full 45A charging current could be fed through the AC ground wire, which would be a significant overload of the ground conductor there and could lead to a fire.)

jjrbus wrote:
I find this confusing, this shows a chassis ground from the neg terminal on the converter in blue and also a chassis ground at the battery. connect neg to chassis at both ends?

There is also a chassis ground lug on the converter housing which must be kept separate, but the blue does not appear to be for that??

My RV has a chassis ground from the battery negative terminal, a chassis ground from the negative terminal on the converter, AND a chassis ground from the frame of the converter.

Think of it this way, when powered by the battery, the battery/chassis ground is current carrying for a short run.

When powered by the converter, the converter negative/chassis ground is current carrying for a short run.

If they were not both grounded to the chassis, ONE of them would have a VERY long return path causing higher voltage loss.

The converter frame/chassis ground is a safety ground.

What mine does NOT have is a wire running from the converter negative terminal directly to the battery. Mine uses the two chassis grounds for that.

I do not get overly concerned about color if I can see both ends.

Here is a copy of the owners manual. I have looked at and read too many things and confused myself. I have already run a #6 THHN wire from my 12V neg buss bar to chassis. And have a chassis ground at house battery, will that hurt anything??

The owners manual seems to support your thought that the blue is for the converter housing ground.

I have not found a installation manual online, I guess the owners manual is sufficient if you know what you are doing?

Yes the Toyota alternator is connected to the house battery with an isolator.

Thanks for any and all input greatly appreciated. Jim

That is a confusing diagram, I agree. I think the blue ground wire at the converter is the converter chassis ground lug to vehicle chassis connection. If it were from the negative output terminal, it logically ought to be black colored and "connected" rather than "arrowed" to it as is shown at the battery negative post.

Perhaps originally the bond of the 12V negative bus to the chassis was done at the 12V battery terminal (with a jumper to the chassis, and another wire to the negative bus bar). If you have an emergency start switch and/or a battery isolator that permits the house battery to charge from the engine alternator, the house battery negative must somehow or another be connected to chassis ground or those features could not work.

In regards to wire colors--while it is very nice to be able to follow some sort of a wire color coding standard for 12V wires, I personally wouldn't worry overly much about it, if only because it's a big enough pain to keep track of how much of any given gauge of wire one needs without also sorting it by desired color. For branch circuits, using one color for ground and one or more other colors for +12V would be worthwhile. (There's more than one semi-standard color scheme for 12V circuits; black=negative, white=negative, etc. As I recall on my Coachmen, for general 12V circuits, ground is generally white with a purple stripe. They were also nice in using a variety of other wire colors for the various branch circuits and uses, and seemingly being consistent about it within a single circuit.)

I find this confusing, this shows a chassis ground from the neg terminal on the converter in blue and also a chassis ground at the battery. connect neg to chassis at both ends?

There is also a chassis ground lug on the converter housing which must be kept separate, but the blue does not appear to be for that??

A two wire system, positive and negative, is required in most newer rigs as the body is non-metallic.
OPs Toyota has a fiberglass shell. He should be running two wires to all devices. He still must connect the negative battery to the frame(chassis).

NO 12V to chassis? Hmmm If all 12V neg run back to battery negative then the battery negative is grounded to the vehicle chassis so the camper is grounded. I suspect that ground is the wrong word here as it is the return wire.

Don't mean to be picky, trying to figure mine out. Jim

The last truck camper I had (Palomino Bronco) had no 12V neg to chassis. The 120V "ground" did tie into the copper propane tubing and the aluminum skin of the camper.

All 12V neg was run back to a buss bar and from there to the 12V battery.

12V neg to chassis really isn't needed and I don't believe it represents a safety hazard. It just makes hooking up stuff easier as you only need to run one wire back to the fuse panel.

My current Forest River 19RR has 12V neg to chassis, but all 12V devices run two wires back to electric closet.

The wiring in this RV had been worked on by PO, I just unhooked everything because it was dangerous. Unfused 12V circuits, loose crimps and such.

Now that I look at the picture I will bet a $1 to a donut that the #10 bare wire I connected to the buss was originally the 120V ground wire!

So what did they use for the 12V to chassis??

Any and all input greatly appreciated. Jim