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Running Your Gas Absorption Refrigerator on the Inverter

Yahoo Message Number: 83503
Scott,

My experience tells me that there is no way to solve your problem without considerable expense. I come to that conclusions because you seem to want to switch your refrigerator to the inverter with the flip of a switch. I would not see that convenience as being worth the risk of having two circuits sharing a breaker. That is no minor violation of the code and also stands out like a sore thumb to any inspector or adjustor.
The fact is that the code's jurisdiction ends at the receptacle except for permanently wired devices. Based on that idea I would plug an extension cord into the entertainment bay and snake it up into the outside refrigerator compartment. There in the compartment the normal 110 volt supply terminates with a receptacle that the refer plugs into. Simply open the compartment and switch the plug to the extension cord when you want to run on the inverter. Now there are no code violations because you simply plugged the refer into a different receptacle via an extension cord. Of course you should make sure that the extension can carry the load and is UL labeled to be absolutely on the safe side.
As for my actual habits I simply put the refer on automatic and never look back. It is designed to operate that way and the only time I shut off my propane is when filling the tank or traveling in restricted areas such as some tunnels. I guess that I have been lucky for 11 years.

Don Seager

2004 Allure 31046

Don Seager

Don - Thanks for sharing your knowledge and experience. I fully support the NEC and understand its value as a safety measure. No issues there. Good points about upstream protection and I fully understand.
My mods deal with the inverter sub panel. Photo here: http://muniac.smugmug.com/Travel/Country-Coach-2006-430-Allure/i-kXCvqtw/0/L/Breakers-L.jpg Applying the upstream protection idea, I have 4 circuits (3 15 amps and 1 20 amp) totalling 60 amps. Upstream from that but downstream from the inverter output is a 30 amp breaker. An interesting choice for a 2800 watt inverter given the breaker won't pop before 3600 watts of power is drawn. Upstream from the inverter's AC input is another 30 amp breaker which is downstream from that leg's (line 1) 50 amp breaker. The inverter circuit uses #10 wire so the wire is protected and so is the inverter when it's in charge mode. That is when it's AC input and AC output are connected together. But when its inverting, the 30 amp breaker is too large. I gather the fallback position is relying on what's integrated into the inverter for protection circuits. Either way I don't think there are any safety issues or hazards with how it's wired and protected. There is always some fiddling room as I'm sure your know.
In my case, it would have been great (and much simpler) to just add a 5th 15 or 20 amp circuit to the inverter sub-panel to run the frig. Physically this just isn't possible since no more spare capacity (or space) exists. I also seem to remember reading in the RVIA specs something about inverters can't have more than 4 circuits attached. So that leaves one in a bit of a pickle. The last resort being to share a circuit that is well under utilized. And that's been my approach in a nutshell.
Based on your experience and expertise, how would you have solved this problem? The problem again being, providing the frig with AC power while traveling. Here you have a perfectly capable inverter that basically isn't being used. And running an 8kWatt genset seems a bit overkill for a 450 watt load. And let's assume the propane option is out. And I have no more space for another inverter either. People with residential refrigerators also face this same dilemma. And I'm wondering how the Allure folks have handled this given their breaker panel situation. If a better, safer, simpler, more practical and cost effective solution exists I'd like to get it out on the table. As of late, what I've done is the best idea I could think of. That's not to say there isn't a better idea out there I'm just waiting for it to surface. Hopefully it can come from this discussion. I like to learn new things.

At 01:44 PM 10/26/2012, you wrote:

Re: Running Your Gas Absorption Refrigerator on the Inverter

Reply #1 –
Yahoo Message Number: 83515
Don - Thanks. You are confirming that no simple solution exists. The same conclusion I came to. I pondered the extension cord idea but quickly abandoned it as a kludge. And yes operational simplicity was a goal for me. Time needs to be logged with my solution. Initially I'm comfortable with it's safety, workability and convenience. All circuit runs are adequately protected and the switching portions are completely enclosed in metal. Codes or no codes, I'm much more comfortable with this than running a rubber extension cord around through the living space of a moving vehicle.
As for codes, it's interesting that the 240 VAC service entrance leads run without any shielding in my small storage bay. Photo here: http://muniac.smugmug.com/Personal-Stuff/Misc-Photos/i-MSpCQm3/0/L/IMG3658-L.jpg I would think this breaks every rule in the book. But I guess it's just a matter of interpretation and who's doing it.
Using propane while traveling is a concern for me as mentioned. But beyond that I'm concerned about how it corrodes the boiler tubing. Propane combustion produces moisture. Until I can get a reading on this I'll opt to use the electric heaters for now. As for your 11 year stretch of good refrigerator luck as you call it, I'd check your boiler tubing for rust. Here's mine after 5 years: http://muniac.smugmug.com/Maintenance/Bus-Repairs/i-Vw9tNGQ/0/M/IMG1176-M.jpg Safe travels.

At 02:19 PM 10/28/2012, you wrote:

Re: Running Your Gas Absorption Refrigerator on the Inverter

Reply #2 –
Yahoo Message Number: 83525
But in the RV WORLD its not truly 240VAC with 120 degrees between the phases. Its two 120 VAC circuits running side by side. Which a is a totally different situation.
TWI 2004 Intrigue 11731
 

Re: Running Your Gas Absorption Refrigerator on the Inverter

Reply #3 –
Yahoo Message Number: 83529
Actually it's 180 degrees not 120 degrees. If you measure the outside legs of the transformer you will see 240 VAC. The center tap (ground/neutral) divides the circuit into two 120 VAC feeds. Take the measurements yourself and see. It is this situation that makes a poor ground/neutral potentially damaging to equipment. RV breaker boxes don't allow direct access to the 240 VAC but the voltage is there. Make no mistakes about it. Safe travels.

At 08:33 AM 10/29/2012, you wrote: