Electrical Schematic

[Dee Bee]

Here is what I have designed as an electrical system for my TD




Comments welcome...

DEE

[Endo]

Dee

I see you grounded the AC but not the DC to the frame. Is a separate DC ground needed? My converter has a positive terminal, negative terminal as well as a place to ground the converter to the frame. I don't know if this will ground my whole DC system or just the converter? Should the terminal bar have a ground to the frame?

[Dee Bee]

What is the best wisdom out there for DC systems? Should the negative terminal be connected to the trailer frame?

I don't have that included in my schematic above?

What do you think is best?

I will be adding an inline fuse on the positive main near the battery, however.

DEE

[Dee Bee]

Here is a new update of my electrical layout...


Here is the larger version
http://www.nfdc.net/home/cbdb/HOLD.htm#Schematic%20Large

You can see I added the ground to frame for the DC system

This is how it all comes together in the TD...


DEE

[Woody]

Can you ground 120 vac and the 12vdc negative ground to the frame and share the "common ground" as it were without feeding back to either side? Can this be done? I thought they had to be isolated. Educate me

[Dee Bee]

Can you ground 120 vac and the 12vdc negative ground to the frame and share the "common ground" as it were without feeding back to either side? Can this be done? I thought they had to be isolated. Educate me

Woody's question is mine too. Will my schematic work?

DEE

[angib]

Why have the switch in the 12v negative line? I can see no reason why you need to isolate the battery negative terminal from the AC-DC converter negative.

Andrew

[Woody]

Actually the other questions, besides safety, I was more concerned about was how would the setup interact with a GFI installed. Since a GFI is looking for a short would the combining the two systems "grounds" would this function be defeated. Considering the 12 vdc negative side has technically electron flow make it sense a short, whereas, the ground of 120 vac does not with some exceptions. Does this make sense?.

[angib]

Woody,

A GFI (assuming it's the same thing as our ELCB, Earth Leakage Circuit Breaker, which it looks as though it is) does not sense anything to do with the ground. All it does is compare what's flowing in the hot wire with what's flowing in the neutral wire and, if there's any difference, it trips. It doesn't mind where the difference is going, it just says if there's a difference, I trip.

So connecting the 120vac ground to the 12vdc negative will not affect the GFI.

On a separate note, who has actively grounded their aluminum skin? It would seem to me to be a much bigger risk that a wiring fault or chafing makes the skin live (do you guys say 'live' as well as 'hot'?), than the frame, and I wouldn't bet my life on the skin being electrically connected to the frame, unless I'd tested it first.

Andrew

[Woody]

So what your saying is, it would be safe to combine the grounds (120vac and 12 vdc) to a common ground (trailer frame) on a dual voltage system?. I am sorry I can't quite make the "connection" on how safe this is. On the bigger RV's are they wired that way with dual systems or is there some isolation from 12 vdc chassis ground and 120 vac ground?. Now looking at an inverter providing a ground on the outlet and mounted on a nonconductive surface or for that matter a conducvtive one. Does this mean that the inverter (120 vac side) is grounded through the 12 vdc wire (chassis ground) which would make it a common ground, but not an earth ground so it is grounded to what? That might answer your electrified aluminum skin theory, the earth ground is what? You reaching for the door knob while it is raining

[Guy]

What Andrew may be speaking about is a catatrophe fuse . Please check out Rvsolarelectric.com for more info.

[mexican tear]

I have the frame tied to the green wireof the 120VAC. The white wire (neutral) also goes to ground. I was getting shocked until I tied the earth wire (green) to the frame.

The 12V has to be grounded to the frame for the trailer lights to work.

I have/have owened many big trailers ant they are all set up this way.

I had a problem with my "pig tail" and it was shocking folks. Now if the plug in place is wrong, it will just pop the circuit breaker and not shock you.

kai

[Woody]

So according to the diagram you posted, they are isolated, 12 vdc chassis ground from the batteries is not tied to the 120 vac ground (green wire) they are separate systems. One using the standard 12 vdc chassis ground, were as, the 120 vac side uses the ground through the three prong shorecord. The catrostrophic fuse looks to be fuse to protect the 12 vdc side from a dead short within the 12 vdc system

[Dee Bee]

I have the frame tied to the green wireof the 120VAC. The white wire (neutral) also goes to ground. I was getting shocked until I tied the earth wire (green) to the frame. kai

Wow I never heard of a frame connection for the white wire of the AC system. Black is the hot or line wire, white is the wire that completes the AC circuit. In my way of thinking
1) bringing the white to the frame makes the frame part of the AC circuit.
2)No wonder people were getting shocked.... the frame was energized by the white wire.
3) Bringing the green wire to the frame carried the frame current to earth ground. But I think the frame is still energized.

I am no electrrician but I can't make sense out of white-to-frame connection.

Just MHO.

DEE

[mexican tear]

The only place they are tied together (green and white) is in the breaker box. Most household breaker boxes are set up that way. If you take an ohm meter between the green and the white. It will read 0. That is the only way they are tied together.

If the frame is not grounded (green) and you reverse the hot and neutral in your cord or the campground has it reversed then it can be a shocking experience. As it was in my case.

Today I had the power hooked up from the house and the truck hooked up at the same time to check everything out. All works well

Sorry if I confused anyone.

kai