Inverter Install

CRoots

New member
So my van (1972 Dodge B350 by Xplorer) was built with "on-shore" power, and associated outlets throughout the interior. There was no inverter in the system at all even though there is a coach battery in the back to power lights and whatnot.

I have installed an inverter on the coach battery, but want to figure out how to power the existing 120 volt circuit (use the outlets). I built a male-to-male power cord, and it worked for a while with a cheap inverter from WalMart, but it finally fried (no sure if my hacked cord had anything to do with it). But now I have a more expensive inverter and am hesitant to use the male-to-male. Any advice or other ideas?


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G35Vortec454

Adventurer
You'll need a transfer switch to isolate your inverter from the shorepower cable. The transfer switch lets you select which AC power is active. Checkout Blue Sea marine electrical panels with manual switch. Or you can get and inverter with a built-in automatic transfer feature.
 

graynomad

Photographer, traveller
male-to-male power cord
Yikes, are you aiming for a Darwin award :)

Yes you should add a transfer switch, make sure it's "break before make" or you will short the two power sources (not good). I would assume they all are but just make sure.

Some inverters will do this for you and even sync the waveforms, but it sounds like you already have one so too late for that option.

____
Rob
 

CRoots

New member
Yeah, I know the male to make isn't exactly ideal, but I was comfortable with the setup I had, and had the plugs very secure. Definitely not something I would condone or do on anything other than my own vehicle.

I guess my question though is how to integrate the inverter to the existing wiring. I don't ever use the shore power capability, I will only power the outlets with the inverter. The only power-out option on the inverter is the three prong outlet, and the system on the vehicle was not designed for an integrated inverter. So besides a male to male, and ideally not hacking the hell out of the existing wiring, how do I power the outlets with the inverter?


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G35Vortec454

Adventurer
So besides a male to male, and ideally not hacking the hell out of the existing wiring, how do I power the outlets with the inverter?

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Get a 30A-to-15A adapter and plug it into your inverter output. Then plug your shorepower 30A plug into the adapter. That simple.

DO NOT use the male-male cable again, it will electrocute/spark/short whatever gets in contact with the open prongs of the shorepower cable, wherever it is.
 
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graynomad

Photographer, traveller
The inverter has a socket right? Run what we used to call a "death lead" (plug on one end and bare wires on the other) into a junction box and connect the wires to your existing system using one of the many standard connection methods. All connections inside the j-box so nice and safe. In Oz all this stuff is available at the hardware store, dunno about the US though. You should really add an RCD and a circuit breaker as well, but few DIYers do I think.
 

verdesardog

Explorer
As one poster said above, just plug the shore power plug into the inverter. Done deal, no back voltage issues ever, no wiring changes, no installation issues.

A male to male set up would not cause an inverter to burn up, it was just probably cheap and/or under rated for your needs.
 

Big_Geek

Drop Bear
Not to be that dude, but it sounds like there has not been a large amount of research put into this endeavor. That usually ends poorly when dealing with electricity. You may want to consider the layout of your "house" electrical system along with how it will be used before making the inverter selection. Also, you need to consider house battery charging (will that be via vehicle? If so, how will you control the separation of house and drive batteries? If not, you will, indeed, need the shore power connection, external battery charger, or solar system.) How were these power outlets inside the van wired to the shore power input? Direct? If so, can you extend them to an inverter? Most of the RVs that I see have this all built into a nice little unit built by a company like WFCO (World Friendly Corporation?). It might be less expensive (and much safer in the long run) if you look into a system from them. If you can find an old RV in a scrap yard or being parted out, you may be able to pick this up (along with a few other goodies) for a song. Even new, smaller ones can be had for around $125. Plus, they mount well, provide circuit protection (fuses and/or breakers on your 120 circuits), and are usually made for direct wire to your outlets.
 
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CRoots

New member
Thanks for all the input! The "house" battery charges off the alternator and is isolated from the starter battery. I didn't state that earlier because its not an issue and not a concern in what I'm doing now.

I like the "death lead" option into the junction box, and I gave it a go and got a protective earth ground fault on the inverter. To check that my wiring was okay, I pulled all my wiring additions out and ran an extension cord straight from the inverter to the shore power plug on the outside of the van. Got the same protective earth fault.

My thoughts are that since the van was not intended to have an inverter, it was assumed that if there was AC power in the circuit, it would come from a source external to the van. Thus it would make sense that the protective earth ground would be integrated into this outside power source. So, if this is the issue, I need to figure a way to ground the inverter solidly enough that it doesn't trip the fault. Maybe use the death lead with the green wire going straight to chassis instead of the junction box??


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CRoots

New member
Just to be clear, the end result I'm looking for is basically using the existing 120 AC circuit in the van as an integrated power strip, just plug it into the inverter and away we go. I do not plan on using the shore power at any time, and obviously if it is used, the inverter will be taken out of the circuit, but again, the shore power capability might as well be ignored minus the info it gives into how the wiring was done originally.


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G35Vortec454

Adventurer
I like the "death lead" option into the junction box, and I gave it a go and got a protective earth ground fault on the inverter. To check that my wiring was okay, I pulled all my wiring additions out and ran an extension cord straight from the inverter.

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Keep the "death" part of it in mind. . . .No offense to whoever suggested it. It's not NEC code compliant. Take care. You've been warned.

With your choice, i'd take out the main fuse (or turn the CB off) leading to the shorepower cable or remove the cable completely to avoid accidents. I hope no one else will connect another male to male ( ie another code violation) in one of the other receptacles.

Edit: why wouldn't you just follow the code? Just to be different? It's not just you, your occupants, your vehicle, but other campers nearby could be endangered when your vehicle catches fire.
 
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dwh

Tail-End Charlie
I gave it a go and got a protective earth ground fault on the inverter.

Got a what?

(FYI: There IS NO "earth ground" on a vehicle unless it's plugged into a shore power that's earth grounded. Another FYI: Under no circumstances should any part of the vehicle or chassis be connected to any part of the AC electrical system. That's dangerous. (And just for the FYI record: A vehicle chassis is a bloody poor ground for a DC system (though not particularly dangerous.))

Normal Ground Fault protection is pretty simple - there are current sensors around the hot and neutral wires and as long as they balance (same out the hot as comes back on the neutral) there is no fault. If those sensors go out of balance, then current is "leaking" somewhere, and the GFI trips.

Yea, that works great most of the time, but a lot of inverters are NOT hot to neutral - many have BOTH legs hot at 60v and out of phase to each other to create 120v between them.

My guess is your truck's wiring has the neutral and ground cross-connected somewhere (prolly in the breaker box if the truck was intended for shore power only). Find the cross-connect where neutral and ground are tied together, and isolate them from each other and your suicide cord (yea, that's the proper name for it) will prolly work.


What's the name/model # of the inverter?
 
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CRoots

New member
Thanks for the advice, I'll look for the cross connected neutral and ground.

I used the "earth ground" terminology because that's what the inverter manual uses. I used it to illustrate the point that I don't have an earth ground, but I think that is what the inverter wants, and is probably part of the issue.

As far as following code...I have no idea what the code is for this particular problem. If somebody would like to enlighten me, I'm all ears, but the reality is that this project is a bit one off and I've run into small issues that I did not anticipate. I figured putting an inverter in an RV with existing 120 wiring should be straight forward, right? Not so much, but I think I've narrowed the scope of the issue to the "earth ground" problem.

Another thing that bugs me is that the male-to-male works (I know, I know), and yet the suicide cord to the junction box would not (yes, wiring was good)...if there is a crossed neutral and ground in the box, shouldn't that cause the male to male to have the same fault?

The inverter is a Samlex 1000 Watt modified sine.


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G35Vortec454

Adventurer
Plug your shorepower to your inverter, using a UL-listed or commercially /retail available 30-15A adapter (vs. not home-made). It's that simple (but it doesn't help your experimentation). Check all your fuses that theyre all good.
 

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