Inverter Power Question

[glenrms]

I try not to write much because I read these forums daily and have learned more than I care to know about our ASs. So, today I had to take out all the front furnishings in my 2012 Signature so I could pull the vinyl floor to find and fix a leak by the door. The inverter is mounted along with all other 12V electrical stuff under the sofa / storage area so it is pretty much hidden unless the furniture is removed.

What I found was the 120v power cord to the inverter that isn't plugged into anything and there is no 120V outlet anywhere near there - BUT the inverter works and I have power at the inverted outlets. How can that be?

As always... thank s to all for helping me understand this.

[Rich W]

The inverter plugs in your AS probably have a blue sticker noting that they are powered only by the Inverter. When the inverter is off you cannot use them for anything. Your inverter uses your 12volt batteries to convert DC to AC power.

The plug on the inverter is probably (check owner's manual) to be used as a pass through. If it's plugged into an AC outlet and your AS is on shore power, the blue inverter plugs are now hot when the inverter is off. When you are boon docking and the inverter is on, they are also hot. When the inverter is off and you're not on shore power, all the AC plugs are cold.

[68 Overlander]

I think Rich is correct. If that is the factory WFCO 600 or 1000 Watt inverter, it has a pass through relay. If that power cord is not plugged in, it will still work but will not detect the presence of 120 VAC and stop inverting when your plugged into shore power/generator, unless they have installed an automatic transfer switch. That is most likely or the shore power would damage that inverter.
What I don't know from his post however is if Airstream wired those outlets marked for inverter to work ONLY from the inverter. I might be missing something but that doesn't make sense.

[Tn Traveler]

If the inverter has an automatic transfer switch the 120 volt outlets are powered through a hardwire connection to the inverter. It is not necessary to plug anything into the inverter. When 120 volt AC is present the switch will automatically select that as the power source. When not connected to AC it will select to invert 12 volt DC battery power to AC.

If that is the case, a notice on your panel box that AC power can still be supplied even without an AC power connection. For safety the inverter should be turned off or better to disconnect it from the batteries. Inverter power can be lethal stuff.

[Rich W]

I have the WFCO 600 inverter and the owner's manual diagram shows the pass through plug. Mine is not connected to AC and my plugs are labeled for the inverter with a blue sticker. I wondered why AS didn't add a 120vac plug for the inverter pass through, seems like a simple thing to do. I have read that others have done this so they can use the inverter plugs when on shore power. I don't think the inverter needs to be on for the pass through to work. It's one or the other.

My owner's manual says there is a built-in 10 AMP rated transfer switch. I don't see any other warnings or cautions. I just says that the change from AC to DC input will maintain a steady AC output for 'sensitive' devices.

[glenrms]

This is correct, 68. I do not have power to my inverted outlets when connected to shore power. In reading the responses, it is now starting to make sense. Thanks to everyone for helping me understand this one.

[glenrms]

Thanks Tn T. I failed to mention in my original post that there is a push-button switch and indicator light on the galley wall for turning the inverter off and on. The owner's manual simple explains what an inverter does and what outlets it affects.

[Tn Traveler]

Originally Posted by richw46

My owner's manual says there is a built-in 10 AMP rated transfer switch. I don't see any other warnings or cautions. I just says that the change from AC to DC input will maintain a steady AC output for 'sensitive' devices.

As a safety precaution a warning label should be at the main panel box. Something similar to this.

http://www.boatlabels.com/Inverter-W...-Label-140.htm

[Rich W]

Originally Posted by Tn Traveler

As a safety precaution a warning label should be at the main panel box. Something similar to this.

http://www.boatlabels.com/Inverter-W...-Label-140.htm

It's a switch on the wall above the galley. Cables go directly to the batteries, not through the main panel.

[lewster]

The main panel box has no connection related to the WFCO inverter that Airstream installs. It is an inverter-only device and is not used for any 120 VAC pass-thru since Airstream has chosen to connect it as a stand-alone system.

There is a single 12/3 ROMEX loop coming from the inverter that feeds the outlets marked with the blue labels, AND ONLY THOSE OUTLETS, which by design are not part of the 120 VAC shore power system.

The system design relies on the breaker located ON THE INVERTER for circuit protection, and no wiring runs thru your main circuit breaker panel.

Since the inverter had no shore power connection and thus no inter- connect to the rest of the 120VAC circuits on the trailer, it is totally isolated from the shore power system and can be energized from the batteries at any time.

There is no possibility of energy co-mingling as again, it is an isolated, independent system.


Lew Farber

[Rich W]

Originally Posted by lewster

The system design relies on the breaker located ON THE INVERTER for circuit protection, and no wiring runs thru your main circuit breaker panel.
Lew Farber

It also has 2 internal 35 amp ATC fuses to protect it from overload. I had to replace these after the PO had plugged in a vacuum cleaner to clean it up for sale. She thought she had fried it.

[mythbuster88]

Pass through enabled on WF-5110HP with extension chord to the unused inverter plug. Don't know why AS does not connect this.