Having Inverter Issues (Long Post, Sorry)

[kaypsmith]

Bill, yes to your question, if you manage the ac circuit with a transfer switch by bypassing the inverter passthrough, the wiring as it was should plenty adequate. The wire size and amperage being used in the pass through mode is inadequate because not only are using current through the inverter but also more current that is required because of the converter using additional current for charging the batteries, especially while in bulk mode. That is why the factory recommends the 30 amp 230 setup. The #12 wire is adequate for 20 amp breakers up to 100 feet and of course you are less than that. I personally think that current starvation is what was killing the previous inverter after doing much study and your post regarding events leading up to the transfer switch failure. To overcome the delay problem with newer ats, I would suggest that house to inverter wiring should be to the generator side, this way the inverter to appliance will be instantaneous. There are ats's available with no time delay on either side but much more expensive, and you will be able to achieve the same result by wiring as I suggested. Good luck with the project. 

[BillAdams]

So are you saying yes, I can remove the 2 120V breakers and install a 230V breaker and use the existing wiring to create the 4 wire run to the inverter.  This would be very easy to accomplish.

[kaypsmith]

Yes, #12 will not support 30 amp load, but you can use a 20 amp 230 breaker, same theory as 50 amp = 100 amps available @ 120 volt twice, 20 amp 230 = 40 amp total @ 120 volt. The #12 wire will overheat before the breaker trips in the event that the power load ever exceeds 20 amps, thereby becoming a fire hazard. The advantage to using the 230 volt breaker does insure that you are truly receiving 230 volts to the inverter as long as the main box is receiving 230 volts, and if one side trips both sides will both become inactive. Also, doesn't matter if you hook only one safety ground to the inverter or use two, I would use both neutrals wired to the same neutral post as you already have it.

[BillAdams]

So, I looked at converting the 2 existing breakers with 4 - 20 amp 120V outputs to 2 - 20 amp 240V outputs.  In thinking about this, it was not an option as I would either have to abandon 2 20 circuits (possible but not willing to work my way through this) to use the 2 available outputs on opposite legs.

So, what now?  I could have tapped directly into the main transfer switch with some 10 gauge wire and run a true 4 wire setup to the inverter Hot 1, Hot 2, Neutral and ground connection but this would not have any kind of breaker in place other than the 50 amp breaker on the power pole.  I may come back to that option in the future but I decided to go backward and try to make the most simple, but least useful, option to see if I can keep the inverter/charger functional for more than a few months.

So, I now have a single 20 amp 3 wires setup running to the inverter.  That means that the charger and the 120V pass-through will share a max. of 20 amps.  I have turned the 150 amp battery charger down to 100 amp (standard in my 2000W inverter) but this can be turned way down or turned off entirely if necessary after a long days travel.

With only a single 3 wire input I only have a single 3 wire output but I have 3 individual circuits that this 1 output needs to power.  None of these circuits use a lot of amps so unless we are running the convection oven I doubt the 3 circuits combined would ever draw more than 20 amps.  This is based on our previous experience with these same 3 circuits that were used successfully with our old Heart 458 MSW inverter.

So while this inverter allows for 2 inputs and 2 outputs, it appears that using only 1 input limits you to the use of 1 output and that's what I have wired up.

I hope you can picture how my outputs are wired but here's my best explanation.  I have taken 2 of the 3 - 3 wire runs and twisted the 2 hots and the 2 neutrals together and placed them into the one output slot labeled L1 (line 1) and N1 (Neutral 1).  One of those 2 lines then run to a coupler that connects the 3rd circuit into this setup.  If I understand correctly what I have done, this basically ties all 3 circuits into the one output (30 amp max inverter circuit breaker but limited by the 20 amp circuit from the breaker box).

Keep in mind that the problem that seems to kill the inverter is something called A/C feedback.  If nothing I have done here should cause any A/C feedback then I should be good to go.  I still don't understand what A/C feedback means or where it might come from to cause a problem but I am hopeful that this will resolve that issue.  If it does, my next project will be to find the right way to feed 240V to the inverter and use output 1 and output 2 to power the necessary circuits PLUS the 150 amp battery charger.

[kaypsmith]

Two 20 amp 120 volt breakers = 1 20 amp 230 volt, a 20 amp 230 is two 20 amp 120 volt attached together side to side with a bus bar that attaches the two switch handles together, and insures that when attached at the breaker panel that they will be on two spades directly side by side in the breaker box, which insures that the two hots coming away from the panel are out of phase with other making this a split phase 230 volt circuit. So you are not using any more breakers, just tying them together properly. Also if you have twisted the ends of the two separate 12 gauge wires together black to black both ends, white to white both ends and ground to ground both ends, you have made a single 9 gauge three wire circuit, of course 9 gauge is not an available wire size at the store but you now have the equivalent of 9 gauge, you can now use a single 30 amp 120 volt breaker at the breaker panel, of course this practice is not to any electrical code, be it rvia or nema, but in practice will work fine.

20 amp 120 volt

20 amp 240 volt

[BillAdams]

I get the concept, just chose to go another direction for now.  Thanks for all of your help.  I will just keep the 20 amp input for now to try to eliminate where the issue might have been before jumping it with both feet.