12 Volt RV Ground ?.

[shadow]

How is the 12 volt house electrical system grounded in older rv`s ?. I`m not talking about the house battery that is grounded to the frame or inner fender. But does the house part of an rv have its own ground ?. I`m just wondering if its something that should be checked, cleaned, or upgraded ?.

 

[TMG51]

:huh:

I'm confused. The 12v ground would be the chassis ground and you indicated you know of that one. What other "house 12v ground" are you looking for? Maybe I misunderstood.

If you're talking about 120v components in RVs that are wired with them, that's actually somewhat of a topic of discussion, as the 120 neutral and ground wires used to be tied together but now the consensus is to float the 120 ground wire.

 

[speedhighway46]

Actually, a convenient way of thinking abt 120vac wiring in any type of moving vehicle is "floating neutrals." Search this topic as it has been discussed at length here.

In a nutshell, at no point should the neutral (usually white) EVER be tied to a ground (usually green). The point which the ground and neutral come together is at the shore power electrical connector, as it does have a true ground bonded to the earth.

Floating neutrals are a must and will eliminate any potential electrical safety hazards on the vehicle.

 

[jimindenver]

I have a line off the negative side of the converter panel going to the frame and there was the same for the battery on the tongue.

 

[Optimistic Paranoid]

Many inverters have a separate 12 volt grounding screw that they want attached to the chassis by it's own wire while the black wire goes back to the battery negative.  I'm really not sure why that is.

 

[rvpopeye]

12 volt ground in an rv is usually distributed with wires just like the positive on those interior lights, if you're replacing existing lights the neg and pos should be there connected to the old one and it won't matter which you connect to which (just don't connect them to each other!)

If you're talking about those clearance lights on the front of the cab over you're rebuilding ....
(It's a fiberglass skin right?) In that case it should be on a wire too.

 

[shadow]

Let me try and explain what I`m asking here. Ok, you have the positive wire coming from the house battery back to the inverter/fuse /breaker panel. From there the power goes out to the lights and what ever else, now when the negative side comes back into
the inverter box, are all of the negative wires attached to a single ground block that is grounded to the frame ?.

I`m not asking about anything to do with the 120 volt part of the system, just the 12 volt side of it, and I`m asking because the ground wires used by most automotive manufacturers and others are way to small in most cases and need to be upgraded for electrical systems to operate properly.

 

[TMG51]

Everything 12v should go back to the battery, and the battery gets grounded to the chassis.

There may be a ground block at your fuse box etc but that block should still go back to the battery, and the battery to the chassis.

 

[GotSmart]

I have my main components grounded to the frame, with the smaller ones grounded to the separate fuse box, which is also grounded to the frame.  Plenty of fuses.  Every component is fused.  Some on each end of a long run.

 

[Reducto]

Yes, it's worth taking a look at your house battery ground wire especially if it's an older rig with the original wiring. Make sure there is no corrosion on either end. If there is, clean it real good, sand off any rust around the contact point on the frame, apply dielectric grease or whatever they're recommending in the dielectric grease thread, and put it back in place.

If the cable looks damaged or undersized then replacing it might be a good idea.

 

[shadow]

Yes, it's worth taking a look at your house battery ground wire especially if it's an older rig with the original wiring. Make sure there is no corrosion on either end. If there is, clean it real good, sand off any rust around the contact point on the frame, apply dielectric grease or whatever they're recommending in the dielectric grease thread, and put it back in place.

If the cable looks damaged or undersized then replacing it might be a good idea.

The house battery ground and the starting battery ground are both bolted to the inner fender, not the best place in my opinion.
So I made two four gauge battery cables and went from the ground terminals on both batteries to the engine block, so that should be a good improvement right there.

That's why I wanted to know how the house 12 volt system is grounded, and maybe it could be improved as well.

 

[SternWake]

The house battery ground and the starting battery ground are both bolted to the inner fender, not the best place in my opinion.
So I made two four gauge battery cables and went from the ground terminals on both batteries to the engine block, so that should be a good improvement right there.

That's why I wanted to know how the house 12 volt system is grounded, and maybe it could be improved as well.

I don't know how or where you House system is grounded. I'd expect as short a path , or as convenient a path to frame as the manufacturer could get away with, with thinner cable than you'd like.  If you can follow the negative cable from the 12v power distribution center, should be near the house dc fuse panel, you can figure it out and improve it.  Might want to upgrade the converter too to a Iota or Progressive Dynamics, and upgrade the cabling  from it to the house battery for faster more complete battery charging when you plug in or run the generator.

Usually a vehicle will have a engine battery to firewall/fenderwell ground in addition to engine battery  to engine ground.

I have made an additional frame to alternator casing ground cable.  From this same alternator casing stud, I have 8AWG cable going to firewall, and 2awg running to my engine block, which continues onto the load/charge side of my 500Amp deltec Shunt.  I have a Bussbar attached to load/charge side of Shunt, to which all house loads are attached.

On the battery side of the  500 amp Deltec shunt I have 2awg going to house battery and 2 awg going to the engine compartment for engine battery, however there is currently no battery there.

 

[Gary68]

on the engine side,the motor mounts usually have rubber in them and the transmissions are usually aluminum with rubber in their mounts which is why your engine should have a ground or two going to the frame

some taillights have only a hot wire and the ground is the screws that mount it

so i am under the impression that anytime you can add a good ground to the frame do it,but lets see what someone with a working brain in the know knows

 

[Virgil Jones]

Maybe I'm not catching it.
Can I run the house battery, inverter, and any other main grounding wires to the interior metal supporting structure of the van walls (probably removing any paint in the way of a connection), or do I have to drill a hole in the floor of the van, run the ground cables thru it and attach the ground to the actual frame.  Isn't the body of the van attached to the frame?

 

[IGBT]

On our RV build I wired the 12V negative terminal of the battery and the ground terminal of the shore power plug to a single point, a bolt on the steel frame of the camper.   Neutral is NOT tied to ground, although the Magnum inverter has internal circuitry that does this with relays.

I use GFCI on all outlets.

You can somewhat check to see if a proposed connection point for your ground has a path to your vehicle frame using a ohmmeter or multimeter.  You would be looking for a resistance value almost exactly the same as if you held the two probe ends of the meter together.   If this connection can handle significant current is another matter and really could only be tested by using a current limited source to run a few amps through the proposed connection.

 

[highdesertranger]

Virgil yes you can ground to the sheet metal of the body. make sure your body has a good ground to the frame and to your battery sources. do not rely on the body bolts for a good ground there are rubber mounts between the frame and body. highdesertranger

 

[ccbreder]

I don't know how "they" do the ground. My main 12 volt draw is the inverter. I have 2/0 cables. Positive with a fuse from battery to inverter. Negative from inverter to buss bar. Buss bar to shunt to battery. I also have a 2/0 cable from the negative buss bar to the chassis. For the lower draw amperes, such as refrigerator and exhaust fan, I have duplex 10 AWG from the buss bars to the point of use. I also ground the negative on the fuse holders to the chassis. For very small amperes, things as LED lights, I have only one wire for positive and the ground is the chassis. There is also safety grounds from the housing of the inverter and battery charger to the chassis. Note; I have a positive buss bar as well, and the positive wires are fused where they come off the buss bar. There is also catastrophic fuse at the battery before the positive buss bar. All the fuses are sized for the wire.