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Old 12-15-2012, 01:21 PM   #11
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Originally Posted by RPAspey View Post
how is the ground terminal of the outlet grounded?

also, unless your inverter batteries are isolated from the camper battery, the negative IS tied to the frame, and IS grounded when plugged into the shore power.

Here's what I'm getting at. I installed an inverter that say explicitly that the inverter is not to be grounded on the neutral side as it was already grounded thru the battery negative. Doing do would cause the inverter to self destruct. Possibly, somehow, maybe yours is similar, and when you plugged into shore power, the neutral became grounded. I dunno.

I did find out why it says not to ground the neutral side of the inverter. The inverter puts out 65 volts on both the hot leg, and the neutral. Anything plugged across would "see" 120volts. I found this out quite accidentally. I installed a flip-flop switch on the hot leg of a circuit. We wanted to be able to change from shore to inverter easily. Well, after installation, we tested the inverter part, ok. then I went to plug into the shore power, I happened to wipe off the plug end and was shocked pretty good. Here, because I didn't isolate the neutral of the switch to the inverter, the neutral side of the camper was energized 65 volts to ground. Had I actually plugged into the shore power, I'm certain the inverter would have been destroyed.

This may or may not be your case.
Any chance you can make a "visual" of what you are describing? I can assimilate better with a "pointy-Talky" better than reading about a subject.

I think you have found realrotor's issue, I just need to see it in a drawing to understand it myself.
Lou
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Old 12-15-2012, 01:47 PM   #12
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Quote:
Originally Posted by RPAspey
how is the ground terminal of the outlet grounded?

also, unless your inverter batteries are isolated from the camper battery, the negative IS tied to the frame, and IS grounded when plugged into the shore power.

Here's what I'm getting at. I installed an inverter that say explicitly that the inverter is not to be grounded on the neutral side as it was already grounded thru the battery negative. Doing do would cause the inverter to self destruct. Possibly, somehow, maybe yours is similar, and when you plugged into shore power, the neutral became grounded. I dunno.

I did find out why it says not to ground the neutral side of the inverter. The inverter puts out 65 volts on both the hot leg, and the neutral. Anything plugged across would "see" 120volts. I found this out quite accidentally. I installed a flip-flop switch on the hot leg of a circuit. We wanted to be able to change from shore to inverter easily. Well, after installation, we tested the inverter part, ok. then I went to plug into the shore power, I happened to wipe off the plug end and was shocked pretty good. Here, because I didn't isolate the neutral of the switch to the inverter, the neutral side of the camper was energized 65 volts to ground. Had I actually plugged into the shore power, I'm certain the inverter would have been destroyed.

This may or may not be your case.
The outlet ground terminal is connected to the corresponding terminal on a 3-prong plug at the other end of 10-foot cable. That plug goes into the outlet socket on the inverter.

Sunforce is very specific that the grounding lug on the inverter must be connected to the vehicle chassis.

Despite that, I think you might be on to something. Thinking back, i realized that when the inverter started smoking the first thing I did was pull the plug from the outlet. The smoking stopped. Seems odd though. There was nothing plugged into the outlet at the time.

I'm wondering whether sun force failed to consider an RV application where a separate AC source exists. Their documentation seems to refer only to vehicles, not trailers.

Maybe I should pull the ground wire.
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Old 12-15-2012, 01:55 PM   #13
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here you go, in a perfect setup, this is what you would have.

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Now say there is a device plugged into the isolated outlet fed only by the inverter. This device has a neutral that is grounded like a power strip with a shorted MOV or a miswired cord or outlet. The neutral of the inverter would be shorted to ground thru the neutral bond at the house panel. It would only cause a problem if camper was plugged in to shore power and the inverter turned on. Now the OP was on a generator. So, the generator ground is tied to what? the neutral. Some generators will do the same thing ad the inverter, put halve voltage on the neutral. not a problem normally. but tie it to an inverter that is sensitive to a grounded neutral, and you might have a problem.

of course without seeing the OP's setup its very hard to prove.

edit: Wait a minute....I mis-spoke the generator outlet ground is tied to the frame of the generator but to get a 120 volt to neutral, the neutral would have to be grounded.
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Old 12-15-2012, 02:00 PM   #14
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Has anyone used two 6 volt gel batteries instead of the one 12 volt installed in there tt?
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Old 12-15-2012, 02:21 PM   #15
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Quote:
Originally Posted by RPAspey
here you go, in a perfect setup, this is what you would have.

Now say there is a device plugged into the isolated outlet fed only by the inverter. This device has a neutral that is grounded like a power strip with a shorted MOV or a miswired cord or outlet. The neutral of the inverter would be shorted to ground thru the neutral bond at the house panel. It would only cause a problem if camper was plugged in to shore power and the inverter turned on. Now the OP was on a generator. So, the generator ground is tied to what? the neutral. Some generators will do the same thing ad the inverter, put halve voltage on the neutral. not a problem normally. but tie it to an inverter that is sensitive to a grounded neutral, and you might have a problem.

of course without seeing the OP's setup its very hard to prove.

I'm becoming more convinced that the frame ground connection is the answer.
What do you think of installing a fuse or circuit breaker in the ground wire? Would that protect against a repeat?
Or what about eliminating the ground completely?
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Old 12-15-2012, 02:30 PM   #16
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if you would plug the camper into the inverter, it should work. I have a buddy that does this with his grounded neutral sensitive inverter.

never fuse a ground.

At home, the neutral and ground shouldn't be tied together except at the main panel in the house. the neutral carries current at no potential.

With an inverter, the chassis of the inverter is grounded and is bonded to the outlet ground. the inverter neutral carries current like in a house, but it could have potential as it's not grounded.

A generator is just like the inverter.

As an aside, there was a safety meeting at work where the speaker, an expert in electrical accidents, said more people are killed by getting across a neutral circuit than contact with a hot leg. current kills, not voltage.
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Old 12-15-2012, 02:54 PM   #17
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I just went out and checked my generator. I have 90 volts neutral or phase to the ground terminal. but 123 hot to neutral. since nothing was plugged in, this doesn't surprise me.

with a heater plugged in, I get 74 volts hot and neutral to the ground of the outlet.
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Old 12-15-2012, 03:01 PM   #18
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Originally Posted by RPAspey View Post
I just went out and checked my generator. I have 90 volts neutral or phase to the ground terminal. but 123 hot to neutral. since nothing was plugged in, this doesn't surprise me.

with a heater plugged in, I get 74 volts hot and neutral to the ground of the outlet.
I am really confused. These numbers do not sound right to me.
What am I missing?
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Old 12-15-2012, 03:12 PM   #19
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my point is that, without grounding the neutral, there is potential on the neutral as well as the hot leg.

the amount of potential to ground I measured means nothing really. just that my generator is working. What really matters is hot to neutral potential.


my inverter style generator essentially no different than a normal inverter. Go ahead and measure the potential voltage from the hot and neutral to the ground on your inverter.

now if th OP has his neutral from the inverter grounded, and his generator is like most....problems.
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Old 12-15-2012, 06:46 PM   #20
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Originally Posted by RPAspey
my point is that, without grounding the neutral, there is potential on the neutral as well as the hot leg.

the amount of potential to ground I measured means nothing really. just that my generator is working. What really matters is hot to neutral potential.

my inverter style generator essentially no different than a normal inverter. Go ahead and measure the potential voltage from the hot and neutral to the ground on your inverter.

now if th OP has his neutral from the inverter grounded, and his generator is like most....problems.
Maybe a dumb question. What is neutral? Would that be the ground terminal?
Should also point out that my generator is an inverter type. AC to DC and back to AC. So with both the generator and inverter running I have two inverters running in tandem. Could that be a Bad Thing?
I have in the past connected the inverter to the camper 30 W connection with no problem.
Also, why does the manufacturer warn of shock hazard if the inverter is not grounded to the vehicle frame?
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