Sine Wave Inverter Anomaly
After following this recent discussion about how to best utilize a sine wave inverter for RV use I decided to go ahead and buy the 1000 watt model mentioned in this discussion since it was on sale for just $199 at Canadian Tire, certainly the lowest price for this size in these parts. My primary use for it is to power 120 vac fans in the camper when dry camping, and based on battery reserve possibly to power our coffee machine, toaster, and my wife's hair dryer, my current limitation of course being the single G27 battery that's presently on the trailer. After musing about it for awhile I decided I'd prefer to wire the inverter "whole house" so I could power the trailer's entire 120 vac system by simply plugging the main service cable into the inverter, the limitation of course being the inverter's maximum 1000 watt rating. I decided to install the inverter on a shelf hung from the joists in the front passthrough compartment where it would be protected from the weather, ventilated, easy to reach, yet occupying otherwise unused space. 6 feet of 4 gauge for both the positive and negative input cables got me to the battery where I ran the positive through an 80 amp fuse. The 120 vac output cable was a few feet of 10 gauge main service cable I happened to have on hand, terminated with a 15 amp Leviton WetGuard connector. For anyone interested, a series of 4 pics starts here.
Time to check everything so although I KNEW everything was wired correctly I proceeded cautiously and before plugging anything in at all decided to check the inverter output with a polarity checker. UH OH ... open ground! :h Hmmm, I never expected that but then I can't say I've ever checked any inverter output with a polarity checker before ... but no question about it, both inverter output receptacles are showing an open ground and indeed if I measure between hot and ground my voltmeter is showing 0 volts rather than a nominal 120 volts as it should and as there is between the hot and neutral. After thinking about it for awhile I decided to go ahead and plug in the main service cable, reasoning the trailer itself would provide the necessary ground ... and bingo, it did. So - it all works just as it should, the inverter easily powers all the aforementioned appliances, BUT I have to wonder why this inverter's output receptacles are not grounded. The inverter does have a chassis stud so it can be grounded to the trailer chassis but that makes no difference at all - it appears the inverter's output is simply lacking ground. Unfortunately the owner's manual is really simplistic and has no schematic so I'd like to ask if those owning a sine wave inverter have ever run into this same situation with their inverter's output not being grounded? :@
Time to check everything so although I KNEW everything was wired correctly I proceeded cautiously and before plugging anything in at all decided to check the inverter output with a polarity checker. UH OH ... open ground! :h Hmmm, I never expected that but then I can't say I've ever checked any inverter output with a polarity checker before ... but no question about it, both inverter output receptacles are showing an open ground and indeed if I measure between hot and ground my voltmeter is showing 0 volts rather than a nominal 120 volts as it should and as there is between the hot and neutral. After thinking about it for awhile I decided to go ahead and plug in the main service cable, reasoning the trailer itself would provide the necessary ground ... and bingo, it did. So - it all works just as it should, the inverter easily powers all the aforementioned appliances, BUT I have to wonder why this inverter's output receptacles are not grounded. The inverter does have a chassis stud so it can be grounded to the trailer chassis but that makes no difference at all - it appears the inverter's output is simply lacking ground. Unfortunately the owner's manual is really simplistic and has no schematic so I'd like to ask if those owning a sine wave inverter have ever run into this same situation with their inverter's output not being grounded? :@
