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Discussion Starter · #1 ·
I have a WIFCO converter which gets its power from a 110 volt power cord, gets 12 volts from my battery set and has breakers for the three 110V outlets in the van, and which then can supply the 12 volts and charge my batteries when it os plugged in, it has fuses for my 12 volt stuff and gets voltage from my battery set or converts it to 12 volts if plugged in for that. Normally the 110 volt outlets are not on of course as it is not a 12-110V inverter.

I also have a 1500 watt inverter that has a pair of 110v outlets and it is fed right off the battery set.
Is there a way to feed the inverter's 110 volts into my outlets from the converter and get the convenience of having 110 volts when I turn on the inverter? I'm thinking no as it would feed the WIFCO back through the outlets. At home I have a UL approved mechanical lockout for my load center for when the generator takes over in power loss situations. It prevents the linemen from seeing my 110/220 volts fed back over the downed lines and allowes only one source- generator OR line power.
Is there a way or do I run additional circuits and label them "inverter" and the present ones "converter"? Since I have only a few and plug only one thing in at a time I have considered split wiring the recepticles and having the top be "inverter" and the bottom being "converter"
If none of this makes sense to you welcome to my World!
 

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... Since I have only a few and plug only one thing in at a time I have considered split wiring the recepticles and having the top be "inverter" and the bottom being "converter"
If none of this makes sense to you welcome to my World!
RD,

That's (almost) exactly what I did at the outlet where my microwave plugs in.

I wired a 2 outlet wall plate with the left outlet fed by shore power and the right outlet fed by my inverter. I wired the two separately instead of splitting one double outlet because even though you can wire each outlet black and white separately, the ground can not be separated. I didn't want any possible ground interaction between 120AC shore feed and the 120AC inverter feed. They are in a plastic box with a plastic plate so there is no ground path through the mounting box. Had I used metal boxes, that would provide a ground path between the two isolated outlets.

Then again, you might run an extension cord from the inverter output to the outside shore power inlet, and make sure the charger/converter is off... fuse might blow.. or, it might just work! It will work for me because I don't have any Wifco box in the van. AC inlet outside (fused) feeds directly to all the outlets inside. My van AC is essentially just one big multi ended (fused) extension cord.
 

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2014 136” HR
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When plugged to shore power, the outlets use shore power. When we turn the inverter on, we also flip two toggles so that those same outlets use inverter power. We do not use the outlets on the inverter.
 

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Discussion Starter · #6 ·
Good suggestions. Thanks all. I'll look through the choices but I'm beginning to prefer the split wiring or dual paired outlets as I won't then forget to switch it accidentally or confuse someone using the camper. Safety is #1 so I would like it foolproof and not have the automatic fail.

I have to think about the grounding- here is another area I might need help. My inverter is not grounded now but has a grounding lug which I can easily connect to the chassis, this is the bare wire (green wire) not the white current carrying negative wire that is not connected to the vehicle chassis or grounded- which it never should be in a RV. The WIFCO and the 120 volt feed to it seem to be grounded to the vehicle chassis via the bare (green wire) which I hope is correct too. If I connect the inverter ground to chassis and the 120 volt is already connected to chassis via its bare (green) wire, isn't it OK to use the receptacles with the bare (green) in common as all those go back to chassis and cannot carry current?
 

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My implementation was to make it as foolproof as possible. I also recall some posts about people having problems in some campgrounds with ground fault issues. With two separate outlets on a duplex plate, black white and green from inverter and shore power have nothing in common. In my plan, the green wire from either power source is not connected to the van chassis...why? Just in case some campground has their neutral and ground reversed. On RV forums I've read that it does happen.

Interested in KOV's switch. To isolate ground too, it should be a 3PDT or a 3PDT relay, either rated for the max current rating of the Wifco, which appears to be 30A at 120vac. For $5, I'd be interested in the current rating.
 

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Next time I go to HD I'll take a photo for you. It's been two years since I did it and I can't accurately recall all the details. I do have a Fluke to check out the line from the grid in (if I remember to use it). I very rarely stay at any campgrounds with hookups, for example, my last five week trip to CA and back I plugged into the grid 6 times other than while at RD's.
 

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Discussion Starter · #10 ·
proeddie,
I understand what you did and why and I do see where it might be a good thing. I carry one of those plug in testers for the outlet I plug into and I think we all should carry one. https://www.amazon.com/Power-Gear-5...1466938915&sr=8-16&keywords=electrical+tester which I got for about $2 at a HF. I do use it.
I'm having a hard time thinking about breaking some long held "rules" about wiring. At this time I have the choice of running an additional wire to the outlet locations and doing the double outlets either split wired or duplex, adding a DPDT or transfer switch, or continuing to plug into the inverter when I use it. The last is the default option unless I add some 110V appliance(s). I asked the question because I was thinking of adding a small hot water heater at the sink since I have found a 750 watt tiny tank that would fit. https://www.amazon.com/Invite-H-HOT...=1466939909&sr=8-8&keywords=sink+to+hot+water
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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On grounding:
In US wiring, the neutral and the ground are supposed to be at the same potential, and should be connected at one, and ONLY ONE, place - the breaker panel. When you are on shore power, the connection between ground (the rig's chassis) and the neutral should be done by the wiring in the pedestal. However, when you are on inverter power, the ground and the neutral need to be connected at the inverter since there is no other place.

If you want to make this automatic, you should get a generator transfer contactor (e.g. http://www.campingworld.com/shopping/item/trc-50-amp-automatic-transfer-switch/67274 but that may be overkill), and have the inverter side of that switch connect ground and neutral (this may already be done by the particular switch you get). Wire the inverter to the "generator" side of the switch, and then it will switch automatically.

Failing that, you could get a DPDT relay rated for the current your rig uses, and wire it up to the system such that when the inverter is powered, the relay is powered and switches to the inverter power. However, unless you are pretty knowledgeable about wiring you may not want to take that on.

You already have your stuff, but to anybody else who is thinking of setting up an inverter and doesn't already have the gear: at least consider looking at an inverter designed for this role, such as the Magnum Energy family (like I went with). The MSH-2012M may seem expensive, but you have the transfer switch, the battery charger, low voltage cut-out (both on the shore power and on the battery), load support (take less power from the pole, make up with the battery), programmable maximum current from shore power, and 2kW continuous/3kW surge output.
 

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This is the switch I used from HD. All I can say is it works! It's rated @ 20 amps/ 125 v. I connected the hot & neutral lines from the outside (grid) to the top terminals and the same from the inverter to the bottom terminals the center terminals feed the 110V receptacles in the van. You can only get 110 V from one source at a time this way. Can't say it's safe or dangerous but it's always worked for me. Just be sure you remember to check out the feed from the grid!



 

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KOV,

Good switch at a good price. I guess it probably should be rated at 30A, but I doubt you're ever using 30A anyway... just took the 30A from the WIFCO unit RD has. No load switching should work out well, (and it has for you!)

Does your shore power AC ground connect to the van chassis?... inverter ground to chassis?

A google for "portable generator grounding" (very similar to inverter grounding) brings up about 121,000 links. Some of the pro electrician sites have debates that go on for pages.... like, "how do I ground my RV generator when a good ground requires an 8' copper rod pounded into the ground?"... tough to pull out when you move to your next campsite.

My feeling is that I don't want to metal chassis of my van to be at all involved in the 120V AC happenings in the van, whether by shore or inverter power. In a lightening storm, I'll be the first to un-hook!

Wowbagger provides a lot of good info, but at a significant cost. Worth it, but expensive!
 

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I must admit I don't really remember but both probably are connected together and to the chassis. I don't know where else they would be connected if not.
I did a similar search and everyone seems to have a different opinion.
 

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Discussion Starter · #15 · (Edited)
Ed, I don't know enough to assess the risks but I have a vague concern with having the generator (or inverter) voltage float and not be referenced to the chassis, but then my home renovations have found non grounded wiring (2 wire Knob'N Tubing).

I simply followed the directions for the WFCO which gave me a large green wire that said "Chassis Ground" or something similar. I would seldom be plugged in anyway like KOV but if I was I would pull the plug out if electrical storms were forecast or showing up on my Radar app on the iPhone. The van itself being a metal enclosure will have no EMF on its interior due to an electrical strike or nearby potential and the insulating properties of the tires should protect against transients. The wires are another matter and the connection represents a danger made worse by the shallow bury or overhead service in campgrounds. I doubt the grounding inside the van will have any great effect on this as the potential of lightening is so high our 600volt cladding on normal wire will not hold it, if we get a strike on the plugged in cord we are in trouble. Unplug

During our Wind-power years we had a lot of experience with lightning. Metal Oxide Varistors can sacraficially help protect the less sensitive circuits but they require a path to a good ground.... and no, I am not driving in a rod or running a wire to ground, or being plugged in!

Wowbagger and others who have knowledge here, I have confirmed the WFCO does not have the ground (bare-green) and the white current carrying neutral connected. I cannot see how grounding the inverter changes this as it has no connection between its ground lug and its neutral (white). All I would have done is to have the van chassis, the inverter chassis and the bonding ground from the 110 plug be at the same potential which will be ZERO with respect to the actual ground if my tester is used. Is this right? Is it OK? Is it smart to do and why or not? I have read the cautions about plugging in to bad outlets.
 

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Here's part of a good series on the subject:
http://noshockzone.org/rv-electrical-safety-part-iv-–-hot-skin/

There seems to be a lot of misconceptions about "ground" - people think you have to have a ground rod to be grounded. While that's true for a building, for something mobile it is obviously not possible. In a mobile installation - be it a plane or an RV - "ground" becomes the chassis.

As for "my inverter does not connect neutral and frame": First, look at the outlets on the inverter; they should be three wire grounded outlet. Check if the ground of the outlet connects to the chassis of the inverter, and if the chassis of the inverter is connected to the negative of the 12V supply. If that's not true, then my personal suggestion would be to throw that junk away before it kills you.

Next, remember the use case for most of the cheap inverters on the market: they are not intended for permanent installations, they are intended to run one (or maybe 2) things temporarily. Many of the people on this forum are buying cheap and then using them beyond their intended purpose. Fine, but then the user needs to add in the features that were not designed into them.

If you are going to go with the simple switch approach, you might try to find a triple pole double throw break before make switch. You can then use one pole to switch neutral, one to switch hot, and one to switch ground (and have the ground and neutral tied together on the inverter side). You need to make sure the switch is break before make - that at no time does it every have both throws connected to the common - or else you can accidentally connect the inverter to the shore power, which will likely let the magic smoke out of your inverter.

Personally, were I adapting a truck stop inverter to RV use, I would use a transfer switch, or a TPDT relay, and I would bring the inverter through a GFI outlet or breaker before feeding the panel, so that if there is a fault it would get shut down quickly.
 

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Discussion Starter · #18 ·
Yea, I guess so. Now I'm so nervous about inverter grounding, fire, Hot Skin, non contact testers, Reverse Polarity Bootleg Grounds, Bonding, floating neutrals and TTDP switches I don't think I'll be able to camp and sleep at night! Who said a little knowledge is a good thing? Or is it a little knowledge is a dangerous thing? Thanks to everyone who has contributed I appreciate it...... really!
 

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Just don't stick your Leatherman in the hot side of the receptacle while taking a shower and you will be just fine - I hope!
 
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