Need to wire it correctly

[Shadow Catcher]

This is an unmitigated whine
As I noted the wiring in Compass Rose (not done by me) had the white leg of the AC and the DC negative 'grounded' to the frame and the controller was messed up as a result. How did I know the there was a problem, I could hear the battery boiling and the converter was stuck on boost at 14.4 V
The cost has just made itself known.
I had to replace the battery for my back up sump pump, one cell was dead, and decided to have the AGM battery from CR checked, and against a new battery it has half the capacity. I had specified a Lifeline (Concord) battery and paid for it, and they substituted a Chinese made AGM which is now junk.

[eamarquardt]

Also, some inverters will not work with the negative terminal of the battery connected to ground. Better to just keep the dc system isolated from the ac system.

Cheers,

Gus

[Shadow Catcher]

The system is now entirely separate with nothing "grounded" to the frame (I learned that from you folks).

[afreegreek]

The system is now entirely separate with nothing "grounded" to the frame (I learned that from you folks).

electricity is something I know nothing about but I did ask our electrician about grounding my Xantrex inverter/charger to the frame as it shows in the manual.. i couldn't imagine why you need to do this since there's a rubber tire between the frame and the (earth).. he told me it's for safety so that if the trailer frame is ever energized by a stray or worn through wire it is grounded and will not electrocute you.. I think you should check with a professional to make sure you're not setting up something that my bite you in the butt later on..

none of my 12v stuff is grounded to the frame, it's all full length wire to the DC negative bus bar.. the exception to this is my running lights.. they are also full length wires but to a separate bus bar that goes on through my 7 pin connector and then grounds to the frame of my TV..

[Steve_Cox]

The system is now entirely separate with nothing "grounded" to the frame (I learned that from you folks).

[bdosborn]

The system is now entirely separate with nothing "grounded" to the frame (I learned that from you folks).

Umm well yeah, there's several codes that require the AC green wire and the battery negative terminal to be grounded to the frame in commercial trailers. But....

Bruce

[eamarquardt]

From this thread:

http://tnttt.com/viewto ... highlight=

The subject of grounding has been discussed a lot. Some of the thoughts expressed make sense and some don't.

Here is what the California electrical code says about grounding in motor homes: 551-56 A) REQUIRED BONDING All exposed metal non current carrying parts that may become energized shall be effectively bonded to the grounding terminal or enclosure of the distribution panelboard. B) BONDING CHASSIS A bonding conductor shall be connected between any distribution panelboard and and accessable terminal on the chassis.

In short: In my understanding, the 120 volt neutral neutral is not connected to the ground plane, at any point, in an RV. This prevents a reversal of hot and neutral resulting in a hot chassis. The chassis and as much of the metal of the RV as practical should be connected to the ground connection point of the distribution panel and then, via the cable connecting the RV to the campground power supply, to the campground electrical ground.

The California Electrical Code is available here:

http://www.bsc.ca.gov/default.htm

I see no reason to ground the negative side of the battery to the chassis as it is better to use dedicated wire for the return of the current from the positive post to the negative post (although the electron flow is from negative to positive) for 12 volt circuits. I see it as a plus to keep the 120 volt a/c and 12 volt dc systems completely isolated from one another. I have seen problems when the ground lead of an inverter is electrically connected to the negative terminal on a battery. It seems tough to keep all the terminology straight.

Cheers,

Gus

[bdosborn]

In short: In my understanding, the 120 volt neutral neutral is not connected to the ground plane, at any point, in an RV. This prevents a reversal of hot and neutral resulting in a hot chassis. The chassis and as much of the metal of the RV as practical should be connected to the ground connection point of the distribution panel and then, via the cable connecting the RV to the campground power supply, to the campground electrical ground.

Yup, that's is the way to do it. The green wire grounds everything. The neutral (white wire) is kept completely separate from all other grounds, just like the hot (black wire). If the black wire happens to touch metal somewhere, the fault currents are conducted to ground via the green wire, the circuit breaker trips and the fault it interrupted. No ground wire means *you* could potentially be the path to ground if a black wire touches metal.

I see no reason to ground the negative side of the battery to the chassis as it is better to use dedicated wire for the return of the current from the positive post to the negative post (although the electron flow is from negative to positive) for 12 volt circuits. I see it as a plus to keep the 120 volt a/c and 12 volt dc systems completely isolated from one another. I have seen problems when the ground lead of an inverter is electrically connected to the negative terminal on a battery. It seems tough to keep all the terminology straight.

I don't use the frame as a conductor either but I still bond the battery to the frame for the same reason as the AC side is bonded; I want a good current return path for faults to return to the battery and open the fuse. Granted, the potential for electrocution is much lower but the principle is the same. I also want my battery ground at the same potential as everything else that could potentially conduct electricity (so it doesn't conduct electricity through me). You have to have a voltage difference to conduct electricity and grounding everything together eliminates the voltage difference.

Now, is it a huge problem if you don't ground everything to code? Probably not as I've never seen a post from someone about being shocked badly. Just don't bond the neutral wire to ground. The fact that most of us are working with wood probably explains a lot. I have to bond everything because I should know better.

There's something wrong with an inverter that doesn't work when the case is grounded. Check out some installation manuals for inverters and you'll find that they all require it.

Bruce

[bdosborn]

I had to replace the battery for my back up sump pump, one cell was dead, and decided to have the AGM battery from CR checked, and against a new battery it has half the capacity. I had specified a Lifeline (Concord) battery and paid for it, and they substituted a Chinese made AGM which is now junk.

Bruce

[eamarquardt]

There's something wrong with an inverter that doesn't work when the case is grounded. Check out some installation manuals for inverters and you'll find that they all require it.

Bruce

I did some poking around and found a site (but I can't find it now, ha). The chassis of the inverter was required to be grounded. The AC and DC parts of the inverter were isolated from each other to the tune of 1500 volts. In the question and answer portion of the manual there was a brief discussion on installing the inverter in a positive ground system. The manual said there was no problem, just continue to connect the battery positive to the inverter positive, and negative to negative which supports their claim that the dc is isolated in the inverter.

I tend to agree that the inverter that I saw not work when the battery negative lead was grounded probably had a problem. I was the "third assistant" on the project and really didn't get involved, trouble shoot, and sort it out. The inverter is rarely used and the next time the trailer happens by I'll suggest we look at it and try and sort it out.

AFREEGREEK made an excellent point that when dealing with electrical stuff, it pays to by quality name brand stuff with good customer support from folks that understand their equipment and can support you when you need it. HF, Pep Boys, and a lot of other sources for this type of stuff offer little to no support and their stuff is pretty much disposable when there is a problem.

Cheers,

Gus