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rugercpl
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# Posted: 4 Dec 2015 09:23am
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I have funny way of powering my cabin but it works well. The cabin is wired similar to a home. It has a panel box, wall switches and outlets but it's off grid. The whole cabin is on one circuit so when I'm on eu2000i generator power I backfeed it into an outdoor outlet and the whole place has power. When I'm
On Solar generator power I back feed from my inverter into an indoor outlet and the whole place has power. It's a little hands-on when switching from one to the other but it takes about 60 seconds and I don't mind it at all.
So when I'm on eu2000i generator power, I recharge my battery bank by plugging in my Schumacher 15 amp battery charger into a wall socket and connecting it to the battery terminals. This has served me well for 2 years with no issues.
My question is, because the battery bank is recharged from the eu2000i but the battery charger is not directly plugged into the eu2000i, could there be some loss of recharging power since it goes through the wires and a few outlets in the house?
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MtnDon
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# Posted: 4 Dec 2015 10:21am - Edited by: MtnDon
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For all intents and purposes the charger is plugged directly into the generator. Unless your cabin wiring is substandard.
MY question back to you is what type of receptacles / cords do you use to perform that backfeed? Hopefully you use a standard extension cord with both a female and a male end and that you plug the "cabin end" of that cord into a special female INlet something like one of these....
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rugercpl
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# Posted: 4 Dec 2015 10:39am
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Thanks Don, I'm quite aware of the dangers of a suicide cord, running with scissors, texting while driving, etc. I would NEVER do any of those things!
Here's another electrical question...if I upgrade to a 25 amp charger, can I continue to do the same thing with my eu2000i? Does the eu2000i have enough power to effectively run a 25 amp charger? Do my standard household wall sockets (15 amp) that I backfeed through and plug the charger into have enough capacity to perform these functions? How about my panel box? Do I need a bigger breaker?
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MtnDon
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# Posted: 4 Dec 2015 02:19pm
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A 25 amp charger is no problem for the EU2000i, not even a cheap charger with a huge initial inrush . But like I stated in some other thread check what the battery mfg says is the maximum current recommended. Then if the batteries are in parallel multiply that maximum by the number pf parallel strings. That is the maximum size charge. Then you need to check if the Eu will operate it. There's no real way to estimate inrush... it varies. Inrush is like the start up surge found with an air a compressor or a refrigerator.
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bldginsp
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# Posted: 4 Dec 2015 03:50pm - Edited by: bldginsp
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rugercpl- What size wire do you have for your circuits? #14 or #12? You said you have a panel box, but also that the whole house is on one circuit. Usually a panel box with breakers feeds several circuits.
Maybe you are ahead of me on this, but here's the potential danger I see- the outlet that you plug the generator to carries current to the panel box via #14 wire. Essentially then, the feeders for the panel are #14. That's fine so long as the breaker ahead of those wires is 15 amp. This would be the breaker at the generator. If the generator has a 20 amp breaker and the wire is #14, you risk overheating the #14 wire to the panel.
Maybe your circuits are #12 wire, on a 20 amp breaker, which is safe. #12 on 30 amp, not safe.
Since you are charging batteries through this system you are running a fair amount of amperage through it, so there is a potential for overload if not adequately protected.
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MtnDon
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# Posted: 4 Dec 2015 04:37pm - Edited by: MtnDon
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Good point on the question of what the cabin wiring gauge is.
Quoting: bldginsp Since you are charging batteries through this system you are running a fair amount of amperage through it,
The math says it's not a big deal. IF we had a 30 amp battery charger we would be using approximately 30 amps x 14.5 volts (charge into battery voltage) = 435 watts. 435 watts / 120 VAC = 3.625 amps. Call that 4 amps. If the charger was a really inefficient unit that is still going to be relatively low AC amps... 8 amps? The inrush when first connected will be higher but that passes after several seconds. Although this is a good reason to buy a high end charger that has a better power factor. At home plugged into the grid a lousy power factor is not much to be concerned about. When power is coming from a generator it can make a difference in fuel consumption and even make the difference between being viable or not.
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rugercpl
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# Posted: 4 Dec 2015 07:06pm
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I'll have to check on the wire gauges and breaker amperage.
I think they are to code for standard home wiring. The previous owner probably was going to hook the cabin up to the grid or at least make it grid-ready.
Assuming it's safe to switch to a 25amp charger such as a Stanley BC2509 from my Schumacher 15A, it's anyone's guess as to how much eu2000i runtime to recharge my bank I could potentially save. I'm intrigued because another person here said he cut his charge time down from 12 hours to 4. That's a fairly substantial savings in fuel, noise, and wear/tear on the eu2000i.
Thanks for sharing your knowledge!
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Bzzzzzt
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# Posted: 6 Dec 2015 10:03am
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Quoting: bldginsp If the generator has a 20 amp breaker and the wire is #14, you risk overheating the #14 wire to the panel.
While you are technically correct, you should check table 310-16 (they've moved it in the last code update) and you will see that THHN #14 wire (which is standard in romex) is actually rated at 20 amps but there is a note that requires you to protect it with a fuse or breaker at 15 amps. While I would certainly advise everyone to go about it the correct way of doing it, I don't think the Honda 2000W generator of which he speaks is going to overload his wiring. At 120V that's only 16.67 amps.
All that having been said, doing it correctly is better and should be done if at all possible. I used #12 for my cabin and had the exact same setup with generator/battery solar. I made a "pigtail" that would either plug into the generator directly or plug into the inverter. Sort of a poor mans transfer switch. I have since switched to on grid power and because I wired my cabin thusly it has made the transition smoothly.
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bldginsp
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# Posted: 6 Dec 2015 02:40pm
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Good points Don and Bzzzzzt. It's probably not a problem as is, but systems tend to expand and diversify over time, in which case the scenario can change with the flick of the switch of a hair dryer. So long as you know what you have and what the capacities are, you can keep it safe.
While backfeeding to a sub panel works, it's really easy to run larger feeders to it and connect the generator to that. Then you are set up when you get another power source.
One other thing to always be aware of- be sure you have a ground path to the generator, and that the generator bonds ground and neutral. Some generators don't, most small ones do (all?). When you have any kind of transfer switch, be sure the bond of ground to neutral remains intact at the power source, never in the sub panel.
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Bzzzzzt
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# Posted: 6 Dec 2015 10:40pm
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One note about bonding ground and neutral, I learned the hard way NOT to do it behind an inverter. They should be completely separate if plugging a panel into an inverter. If they are bonded together you will release the magic smoke inside the inverter.
Good luck making heads or tails out of all this shop talk, rugercpl. LOL
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bldginsp
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# Posted: 6 Dec 2015 11:09pm
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Bzzzzzt- now that's interesting. I don't know much about inverters, but if ground and neutral are not bonded somewhere the breaker can't open in a ground fault.
Also, if bonding neutral to ground will fry an inverter, then with a setup with both generator and inverter with a transfer switch you could fry the inverter via the connection of the ground and neutral at the generator. That is, if the transfer switch is the type that does not switch the neutral (the more common setup). Bizarre.
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Julie2Oregon
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# Posted: 6 Dec 2015 11:34pm
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Can't you hardwire your solar generator to your breaker/electric panel and use a transfer switch to your other generator to charge your batts? That's what I'm planning to do. Tentatively, this system, to which I will add a few more panels and sub in lithium batts. This company lets you customize.
http://www.bepreparedsolar.com/solar-generator-for-well-pumps-10k-watt-240v-p/240v.ht m
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MtnDon
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# Posted: 6 Dec 2015 11:51pm - Edited by: MtnDon
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That is absolutely correct about the magic smoke loss with portable inverters connected to a service panel that has the N-G bond inside the panel.
IMO, a transfer switch should always switch the hot and neutral conductors in a "break before make" order. It makes everything simpler if you always use a TS with two poles (for 120 VAC).
Inverters designed for RV use such as the mobile series from Outback and Magnum have internal switching that includes making and breaking the bond.
The RV accessory transfer switches I have seen all switch hot and neutral (120 VAC).
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Bzzzzzt
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# Posted: 6 Dec 2015 11:54pm
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Quoting: bldginsp if ground and neutral are not bonded somewhere the breaker can't open in a ground fault.
In my situation I had a panel that was bonded as such and worked just fine with a generator and a cheapo harbor freight inverter. After I let that one get rained on and it blew up I bought a better quality inverter and it fried the instant I plugged the panel pigtail in. Took me a lit of research and headscratching to figure that one out because, like you, I thought they HAD to be bonded. I think it was actually MtnDon that turned me on to info that enlightened me on the subject. Anyhow, I took out the jumper and it worked fine. Since then I took all of that out and had power run in from the local utility. WAY easier. That stuff I am a master with..... Literally! LOL
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toyota_mdt_tech
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# Posted: 7 Dec 2015 02:16am - Edited by: toyota_mdt_tech
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I can confirm a bonded ground/neutral will in fact, release the smoke on a nice inverter. Xantrex 2000 (1000 continuous) to be specific.
Good thing it was new and under warranty from Costco. I changed the wiring around. I don't use a transfer switch, I use a plug. Its in my enclosed cargo trailer and I plug the cord into the one shore outlet inside the cabinet to power up all inside outlets and if I want to use inverter, unplug it from the single shore power outlet and I plug the cord into the inverter outlets directly. Not fancy, but will not release the smoke. 
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bldginsp
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# Posted: 7 Dec 2015 08:45am
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Ok, I'm lost- why would a portable inverter, which already has a N/G bond inside of it, fry if there is another such bond past the inverter?
Do the installation instructions caution against this?
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Bzzzzzt
Member
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# Posted: 7 Dec 2015 09:45am
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I checked mine with a meter and there is NOT a bond between them on the inverter. Seems like there should be, but nope.
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MtnDon
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# Posted: 7 Dec 2015 10:24am - Edited by: MtnDon
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Quoting: bldginsp Do the installation instructions caution against this?
Not in mine. But apparently some may. According to a search this AM.
More in a minute
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MtnDon
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# Posted: 7 Dec 2015 10:51am - Edited by: MtnDon
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Apparently this is more complicated than I thought. Apparently there are some portable inverters that do have an internal bond. And there are some portable inverters that do not. However, those will still blow up if connected to a service panel that has a neutral - ground bond. Why?
Some portable inverters use what is called a half voltage system. They output half the voltage (60 volts) on the black (hot) wire. The other half (60 volts) is output on the white (neutral) wire. When we plug something into the built in receptacle it sees 120 volts and it works.
When we connect the receptacle to a service panel that incorporates the neutral-ground bond we have a direct short circuit to ground. Does that short to ground occurs because we have conscientiously installed a ground rod to earth? It would seem if the cabin system had no earth ground the inverter might not blow up. THAT MAY BE THE CAUSE BUT I DO NOT MEAN ANYONE SHOULD TRY TO SOLVE THE INVERTER SMOKING ISSUE BY NOT GROUNDING TO EARTH. Rather it probably means that we should not use equipment in manners they were not designed for.
My pure sine wave Xantrex and Samlex inverters do have an internal bond. My modified sine wave unit does not have a bond. I just checked. Maybe it makes a difference if the inverter is a cheaper mod sine wave or a more expensive pure sine wave? Just wondering?
~~~~~~~~~~~~~
Some info I copied from Samlex.....
"In some inverters designed for portable use, the two current carrying conductors connected to the "Line/Live/Hot" slot and the "Neutral / Return / Cold" slot of the receptacle ( for example, 15 A NEMA5-15R) are isolated from the metal chassis of the inverter. In these inverters, none of the two poles can be called Neutral as both these poles are isolated from the chassis of the inverter. Both the Line and Neutral slots of the receptacle will be at an elevated voltage with respect to the chassis - normally around 60 VAC (Half of the voltage between the two current carrying conductors). Hence, do not touch the neutral slot of the receptacle!
These types of inverters are designed to be connected directly to the AC loads. These are not designed to be permanently installed into household or recreational vehicle AC distribution wiring. As this type of connection / installation can not be classified as a permanent installation, the NEC requirement of grounded distribution system doesn't strictly apply.
The UL standard for this type of inverters- UL458 does not have a requirement for a bonded neutral on the output of inverters. As long as the installation requirement of grounding the chassis of the inverter has been accomplished, loads that are plugged in will have their chassis held at the same ground potential as the chassis of the inverter and the house or RV. The only difference is that the neutral slot of the receptacle has approximately 60V on it instead of the usual 0V. The impact of this is minimal, since parts of wiring and equipment that are connected to the neutral side of the circuit are required by safety standards to be treated as if they were at 120VAC, since there are many receptacles that are wired backwards or 2-prong plugs that are not polarized. Therefore, a voltage of approximately 60VAC of the Neutral slot is not accessible to the user, and any shock hazard presented is mitigated by lack of access. The main safety agencies, CSA, UL, and ETL, have all approved inverters with this half-voltage on the neutral scheme."
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bldginsp
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# Posted: 7 Dec 2015 03:15pm
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Thanks for the info Don. I wasn't aware of the 60/60 split on some inverters. But I question whether the frying is because of a short to earth. The bond at the service causes the grounds to be charged with 60 volts, which goes to the ground rod to earth, but then how does it get to the black 60 volt wire to complete the short?
Here's a guess- the hot ground system energizes the frame of the inverter. The manual you reproduced tells us that the frame is isolated from both black and white hots, but with the whole frame energized, arcing could happen anywhere. So I'm guessing that's how the short circuit is completed.
Earth is a lousy conductor so I can't see a short with a path through the earth as a viable scenario. But even if so, the black is isolated from earth.
Post if you come up with more. I wonder if the folks at Arizona Wind and Sun could enlighten us. Or- am I missing something here?
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Julie2Oregon
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# Posted: 7 Dec 2015 05:19pm
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Interesting. The company from which I plan to order my solar generator equipment designates some packages that can be connected to the breaker panel but most cannot. Among those designated as "tie-in" systems that CAN be connected, there are a few with modified sine wave inverters.
Does an inverter beijng modified sine wave reflect that build quality of the inverter? Should I absolutely stay away from modified sine wave?
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rugercpl
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# Posted: 7 Dec 2015 05:59pm
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Quoting: bldginsp While backfeeding to a sub panel works, it's really easy to run larger feeders to it and connect the generator to that.
I have a large feeder that hooks direct to my eu2000i (companion model) via a 30amp cord set and receptacle. It's wired directly to the panel box. I don't use it since it's a little less convenient putting the eu2000i under the house than it is backfeeding right outside my door into a dedicated inlet.
Wow i opened a can of worms here. I really got lucky I guess that everything just works....no smoke, no flames, no overloads. Maybe i should leave well-enough alone 
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MtnDon
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# Posted: 7 Dec 2015 06:23pm - Edited by: MtnDon
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Quoting: Julie2Oregon Does an inverter beijng modified sine wave reflect that build quality of the inverter? Should I absolutely stay away from modified sine wave?
My beliefs are that if you plan to run anything with a motor or electronics that are meant to be run on 120 VAC grid tie power as a more or less permanent setup , then you should use a pure sine wave inverter. The reasons center around the fact that motors run cooler and are more efficient when on pure sine wave like the power grid supplies. The magnetron tube in a microwave operates much more quietly and much more efficiently on pure sine wave. A friend who has been living off grid since 1992 and designing and selling systems has told me that he has seen fewer problems with all things electronic when the inverter is a pure sine wave. He will not advise his clients to us anything but pure sine wave any more.
So that sort of leaves incandescent bulbs as being okay along with things that use resistance elements for heating... space heaters etc. And most of those should not be used very much in an off grid situation
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Julie2Oregon
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# Posted: 7 Dec 2015 08:17pm
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Thanks, MtnDon! I'll stay away from modified sine wave. Glad I asked! All I'd previously seen was that the only difference was in video quality and such with electronics!
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Bzzzzzt
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# Posted: 7 Dec 2015 09:10pm
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Quoting: bldginsp Earth is a lousy conductor
I can personally disagree with that statement. I wired a church in Russellville, Arkansas several years back and they were having trouble with their sound equipment and so they wanted us to drive a ground rod just for it and run a #8 wire to the new ground rod. I accomplished this by breaking into a conduit that fed an outdoor receptacle and driving the ground rod next to that plug and pulling the #8 unbroken all the way from the sound equipment rack to the new ground rod. This rod was approximately 75-80' away from the main service. Just for kicks I took a good ohm meter and checked between the ground wire existing at the receptacle and the new ground rod. 0 ohms resistance. I'm sure the soil content and moisture in the ground play into it but it surprised me, to say the least.
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Bzzzzzt
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# Posted: 7 Dec 2015 09:13pm
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Quoting: rugercpl no smoke, no flames, no overloads. Maybe i should leave well-enough alone
It would be my professional opinion as an electrician that if it ain't broke don't fix it.
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bldginsp
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# Posted: 7 Dec 2015 10:43pm
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Bzzzzzt- correction- earth is often a lousy conductor, depending on conditions. I wonder if you could get enough short circuit current through the earth to fry an inverter. But that wouldn't be a short, it would be a ground fault. Still the issue is whether enough current could pass thru the earth on its way to the inverter to allow the inverter components to heat up enough to burn.
Oh, and don't breath the fumes.
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Bzzzzzt
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# Posted: 7 Dec 2015 11:14pm
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I Think the main problem only exists with these inverters when there is a direct bond between neutral and ground after the inverter. For instance, most panels have a green screw that you CAN install to bond the neutral bar to the ground. If this connection is actually made it would actually make 60v go directly to the ground lug on the inverter thus releasing the aforementioned magic smoke. NEC says that the neutral and ground can only be bonded at the first disconnect and should be separate thereafter. I dont think I can really articulate it better than Don did earlier in this thread.
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MtnDon
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# Posted: 8 Dec 2015 12:01am
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Quoting: Bzzzzzt ...most panels have a green screw that you CAN install to bond the neutral bar to the ground. If this connection is actually made it would actually make 60v go directly to the ground .....
That is exactly what I was meaning.
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Don_P
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# Posted: 8 Dec 2015 12:09am
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Give me a takeaway lesson.
Is it;
If I ohm the receptacle on an inverter and it is not bonded, I cannot get continuity between either slot and ground.
Then a panel cannot have a bond between neutral and ground, Nor can anything downstream of that inverter.
?
At my electrical skill level I've learned to buy cheap meters and need to go get another. Can I read if it's the half volt system by checking either slot to ground for 60 volts...or will I simply realize that it was a half voltage setup?
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