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Old 07-29-2016, 01:41 AM   #11
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Unless they are specified to sync their sine signal, I think there is an element of danger here.

The neutral wire in an AC circuit is intended as the return path to the current source. With a pair of non synchronized inveters you are creating the distinct possibility of some sort of bastardized 2 leg ac system, especially if you share or tie neutrals intentionally or not at any point.

An actual 2 leg common neutral system has the current out of phase, thus as one current path crosses the voltage drop threshold, the other rises, utilizing the "slack" in the current use.

This would give you a reliable 240 volts between your two legs. If you have the bastard system with the phasing wrong, you are possibly sending far more current on your return neutral than the wire is specified to load. This will fry items powered from the line, and possibly set the wiring on fire by overloading your neutral since its not a neutral anymore.

Don't do it, unless you can ensure it is being done right.
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Old 07-29-2016, 08:25 AM   #12
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have the rules of grounding AC changed?

imo, an AC ground needs to be a wired floating ground on the system. not a system grounded to the 12v vehicle. with out a ground rod, there is no place for the current to go.

i can only see the probability of this arrangement hot skinning the bus any time the ground circuit is energized.

and with the half phase of the set up, i think that means hot skin most of the time.
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Old 07-29-2016, 08:33 AM   #13
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Originally Posted by turf View Post
have the rules of grounding AC changed?

imo, an AC ground needs to be a wired floating ground on the system. not a system grounded to the 12v vehicle. with out a ground rod, there is no place for the current to go.

i can only see the probability of this arrangement hot skinning the bus any time the ground circuit is energized.

and with the half phase of the set up, i think that means hot skin most of the time.
Mike Sokol explains why this is not correct in his book RV Electrical Safety and for us he explains this starting on page 9, post 88 of this thread: http://www.skoolie.net/forums/f10/ho...ac-448-14.html

I'd read the thread from page 9 to the end.

ALL grounds go to the chassis.
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Old 07-29-2016, 09:00 AM   #14
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The suggestion from Dapplecreek to divide the bus so that each inverter handles only part is interesting. If you had just two inverters, you could use a conventional 120/240 volt breaker panel for the distribution and wire one inverter to each hot leg in that panel.

It would only add one more switch to the diagram quoted earlier. Add a switch for the second inverter, just like the one shown between the first inverter and AC panel.

The "upstream" side of the two switches, going to the shore/generator selector, could be tied together. In this way the two hot legs in the panel would be isolated when fed from inverters, but tied together when fed from other sources.
I understand. Keep the hots (black wire) from the inverters separate, but join ALL the neutrals (white wires) to the neutral bus bar in the panel and run grounds to the chassis.

One more switch, a panel and a TWO 20 amp breakers.

I think I can even draw it.
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Old 07-29-2016, 09:19 AM   #15
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Just for clarity ... we are ALL agreed, even me, that "stacking", or bonding the hots (black wire) from the inverters is a big NO-NO!

Don't do it.
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Old 07-29-2016, 10:12 AM   #16
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With that said, I'd be OK with inverters supplying separated circuits. I would require independent disconnects for the circuits when connecting to shore power. (Some savings is lost by doubling your disconnect hardware)

Quote:
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Just for clarity ... we are ALL agreed, even me, that "stacking", or bonding the hots (black wire) from the inverters is a big NO-NO!

Don't do it.
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