Electrical Schematic

[Dee Bee]

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

Thanks for the info but how are green and white tied together in the breaker box? I don't plan on intentionally connecting white and green together. Please clarify!

DEE

[toypusher]

Kai,

Don't you use a 3-prong plug (grounded)? If so, you can not get the hot and neutral reversed and the shore power should already have earth ground. In the sticky section here, there is a discussion about all this.

When I was trying to get a wiring drawing completed, I was told specifically NOT to tie the neutral and ground together on the AC side.

Kerry

[mexican tear]

I just went out and looked at my wiring and the white is not tied to the green. That is the way it should be. If they get together it should only the "shore" side.

I was thinking about houses and answered to quick. Thanks

Thats what great about this forum, we can get this stuff worked out and every one get it so much better than trying to do it yourself.

kai

[Dee Bee]

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

DO you think it would make sense then to place the in line fuse on the negative line as a catastrophic fuse?

Hope we can get more input here from those with electrical knowledge...

DEE

[Dee Bee]

Dee,

I think the switch for the meter should be on the 9V power source.

I'm not sure why you have a switch in the ground to the battery and converter. The ground is typically never switched so that it isn't accidently lifted.

The hot wire for the converter is not fused.

You might clarify that shore power is circuited to the line side of the GFCI receptacle and the remaining devices are circuited to the load side. You kind of show that in the diagram but it wouldn't hurt to add a note.

I don't think you need the SPDT switch just upstream of the fuse box unless the SPDT switch for the battery and converter isn't a cutoff switch. It should be a DPDT with center off if you are using the switch to toggle between the converter and the battery.

The neutral and ground wire should be routed around the circuit breaker instead of through it since the breaker only works on the hot wire (but this is being a bit nit picky).

Hope this helps,
Bruce

Bruce,

It helps a lot! Thanks for taking the time

1) I will bond (ground) AC and DC to trailer frame.
2)I had a switch on the 9 volt battery but didn't show it. I ran the meter line through a SPDT just because I had a spare one in my panel and didn't have an empty SPST.
3) I have the switch in the ground to the battery because I wasn't sure how the converter would function is the grounds were tied together. This shows my lack of knowledge... My question is this If the DC current is coming from the battery will the electrons return only to the battery, would they flow to both the battery and converter? How would this affect the battery?
4) I fused the hot wire from the battery as a catastrophic fuse. But now I have read that the catastrophic fuse should be on the negative pole between the batery and the frame. Please advise on this.
5) I did have the GFI wired as described but added info to schematic
6) The SPST upstream of the fuse box is a kill switch near the box. Not essential but convenient in my application
7) Please explain what a DPDT is compared to the function of SPDT. The SPDT between the converter and the battery positive line does toggle betwene the two sources of DC current, center possition is off. In off positiion it is also a cut off switch as the DC loads are not energized in center possition
8) AC neutral and ground are routed around the breaker but are in the breaker box

I appreciate your knowledge and your help



DEE

[Woody]

Dee Bee

I went and asked a friend who is an Electrical engineer. I asked him about the 120vac ground and the 12 vdc ground both being tied to the frame. He said if the shore power ground is bad at the hookup, you run the potential of feeding back 120 vac into the to the 12 vdc side and that would be a bad thing. He stated that an 120vac earth ground (green wire) and the negative ground of the 12 vdc side are technically different and should not be confused as the same type of "ground". When you "ground" the dc side to the frame it actually make the frame part of the dc circuit which is very different of a 120 vac earth ground. Hate to see anyone get hurt here from some bad info. Hope this helps from the earlier dicuusion we had in this thread

[toypusher]

I am still unclear on the real need to ground the 12VDC to the frame. At least in my setup, all of the circuits will have 2 wires and everything will be connected to the exact same point for the positive side on the positive side of the battery and all negative connections will be returned to the negative side of the battery. The circuits are all complete and all will be protected with circuit breakers.

Kerry

[Dee Bee]

Dee Bee

I went and asked a friend who is an Electrical engineer. I asked him about the 120vac ground and the 12 vdc ground both being tied to the frame. He said if the shore power ground is bad at the hookup, you run the potential of feeding back 120 vac into the to the 12 vdc side and that would be a bad thing. He stated that an 120vac earth ground (green wire) and the negative ground of the 12 vdc side are technically different and should not be confused as the same type of "ground". When you "ground" the dc side to the frame it actually make the frame part of the dc circuit which is very different of a 120 vac earth ground. Hate to see anyone get hurt here from some bad info. Hope this helps from the earlier dicuusion we had in this thread

Thanks

DEE

[Dee Bee]

I am still unclear on the real need to ground the 12VDC to the frame. At least in my setup, all of the circuits will have 2 wires and everything will be connected to the exact same point for the positive side on the positive side of the battery and all negative connections will be returned to the negative side of the battery. The circuits are all complete and all will be protected with circuit breakers.

Kerry

Let's ask others who can clear thisup...


DEE

[mexican tear]

If the 12V is not grounded, how are your trailer lights going to work?

kai

[exminnesotaboy]

If the 12V is not grounded, how are your trailer lights going to work?

Kai, I am not sure if you are referring to the trailer(brake, directional, etc..) or anything else(cabin lights, 12v outlets, etc..)

in my case, my 12v teardrop(cabin, galley, etc...) circuits are completely independent of my trailer lights. I have my trailer lights grounded to the frame, but I currently don't have my 12v cabin system grounded to anything other than the battery(and the battery is not grounded to the frame)

due to my lack of knowledge in the electrical field, I have read every post here regarding whether you should ground your 12dc battery to the frame - and there are people that do it and don't do it. I am still in the construction phase so I can add a battery ground if need be - so, I too, am interested if anyone has any new input on this...

[mexican tear]

Anthony
As long as you do not desire to charge the battery or use the breakaway swithch then all should be OK. I like to charge the battery while I drive and after loosing a trailer once, I always have a breakaway switch.

kai

[Geron]

There is no need to ground the Trailer battery to the chassis.

The Chassis lights are already grounded (negative side) to the Chassis which is grounded (negative side) to the TV. That's where the power for them comes from.


Geron

Edited - learning curve elevated.

[Woody]

When you complete the dc side by hooking the positive and negative (the ground) all you are doing is completing the circuit, the electron raceway. The trailer lights have nothing to do with the teardrop dc circuit and is wired separately. The ground and power for the trailer lights comes from the car thru the umbical ( the white wire is the ground on a four wire plug) again has nothing to do with the teardrop dc circuit. Exception to this is and only the time it would is if the tow vehicle is wired to charge the battery in the trailer, then they would share the chassis/ frame ground from the car and the trailer to complete that particular wired circuit. A 120 vac ground is not the same as the ground in the 12 vdc circuit, which is the negative side of the battery, and should not be confused with a green wire/bare copper- true earth ground. They are simply are not the same animal. Most people during there build have run two wires for the dc side any way so it is not necessary to attach the negative side of the battery to the frame anyway. From what I have seen everyone including myself have combined the 12vdc grounds in the area of the fuse/circuit panel anyway, then to the negative side of the battery The grounding for the 120 vac side is done via the three prong plug when pluged into a properly grounded source of 120vac power. So if you wire the trailer for 120vac and connected the grounds/bare copper wire when wiring to that circuit breaker panel, it would use the shore power connection for the ground. If the two grounds, 12vdc and 120vac. are tied together and the 120 vac has a bad ground at the shore power connection the you run the risk of 120 vac feeding into the 12vdc circuit if and when the 120 vac side has a problem or a short and that is bad and unsafe. I would wire them as independant systems and keep it that way you'll be safe

[Guy]

The negative DC ground with a catastrophe fuse is inportant when you are using an inverter in order to protect the dc charging system (if charged off the tow vehicle), the inverter, solar panels, and the battery. In order to necessitate the negative ground catastrophe fuse you would have to be using an inverter higher than 750 watts because such an inverter throws off enough amps to destroy a battery bank in double time.

Woody is quite correct, you no one should confuse the 120 VAC ground with the the 12v ground. However, in this as in any other issue regarding teardrops, one size does not fit all. Each builder must analyze their particular electrical set-up and act accordingly.