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Old 10-16-2022, 02:10 PM   #21
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The manual for it shows Hot 1 - Neutral - Hot 2. How they may be isolated from each other inside would determine if you can or can't hook up 240VAC where it's 240 to neutral, vs. 120VACph1 - N - 120VAC "antiphase1".


I should add, yes, 120VAC in domestic US wiring is a 240VAC to 240VAC transformer, isolated secondary from primary, secondary center tapped -- and to that center tap all neutrals go. Also grounded to earth at that one center tap point of entry-into-house side wiring.

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Old 10-16-2022, 02:43 PM   #22
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aha, yes i skim because you folks are light years ahead of me.

i do find 30a only campgrounds, and i too have a 50a hookup. it happens. the same campgrounds also prohibit my 12k gen operation.

i can run on my 15a without cooking.
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Old 10-16-2022, 07:58 PM   #23
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The 240 VAC power that comes into your house has four connections:
L1 - 120 VAC
Neutral - a common connection between L2, L2

L2 - 120 VAC 180 degrees out of phase with L1
Ground - connection to earth ground at some point


A connection between L1 and L2 will provide 240 volts.


In my "new Crown" I have wired the outside power connection using a standard connector used for 50 amp service provided at RV parks. This power connection goes into an off the shelf Siemans electrical panel. L1 connects through a one side of a ganged 50 amp circuit breaker that is connected to one of two bus bars in the panel, and L2 connects through the other side of the ganged 50 amp circuit breaker that connects to the second bus bar in the panel. Opposite the ganged 50 amp circuit breaker is a second ganged 30 amp circuit breaker. That 30 amp ganged breaker connects to L1 and L2 from the 6.5 Kw Onan generator under the floor of the bus. These two ganged circuit breaker are mechanically linked together so that turning the ganged breaker for the outside power on forces the ganged breaker for the generator off. This same mechanical linkage will also turn off the outside power breaker when the generator breaker is turned on. All of this provides a safe way to switch between outside or generator power.


My understanding of 30 amp services provided at RV parks is that they are 120 VAC service. There is 3 pins on the plug that goes to a 30 amp service.


Those pins are:
Hot - 120 VAC
Neutral
Ground


When using a 30 amp to 50 amp adapter cable:


The ground pin of the 30 amp plug connects to the ground socket of the 50 amp socket.


The Hot 120 VAC pin of the 30 amp plug connects to both Li and L2 sockets of the 50 amp socket.


The neutral pin of the 30 amp plug connects to the neutral socket of the 50 amp socket.


Basically this means that both L1 and L2 are tied together when a 50 amp wired RV is connected up to a 30 amp service. All 120 VAC circuits works normally. No 240 VAC circuits will have power.


I used my ohmmeter with an off the shelf 30 amp to 50 amp adapter cable to make this determination, although I had previously known about this.


If you have an inverter that OUTPUTS 240 VAC to your bus this would be no problem as long as you NEVER EVER try to connect your inverter to outside 30 amp power. You should NEVER have both your inverter and outside OR generator power connected together.


My electrical panel has a second set of bus bars with circuit breakers installed (my modification) and connected to each other through circuit breakers. The second bus bars connect through ganged 30 amp breakers that provide power to both L1 and L2 when either the outside or generator power is selected. The second set of ganged mechanically linked breakers in the second set of bus bars also connect to the inverter, which is a 120 VAC output. Because the inverter can only be on-line when the power from outside or generator is disconnected it is safe to connect the Hot wire from the inverter to both L1 and L2 in the lower half of the panel (through circuit breaker).


I hope this answers your questions about 240 VAC - 120 VAC power.


In Europe they use 220 VAC 50 Hz power, meaning an outlet has 220 VAC between hot and neutral. Asia is that way also.
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Old 10-16-2022, 08:26 PM   #24
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So, the main breaker box does have the neutrals going to ground there, sub-panels should not. Main breaker box is where house wiring neutrals go to ground.



Just saw this. I may have gotten the wrong manual before.


If you have the manual "Off Grid Solar Inverter Split Phase 4KW-12KW" and the SPF 8000T DVM or SPF 8000T DVM-MPV inverters, it only has Hot 1 and Hot 2 and a Ground connection for incoming AC. No neutral involved. Any 120VA to 240VAC wired transformer will do this from the 30A 120VAC RV connection, you don't need a center tapped (with neutral) secondary to feed the inverter.


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Old 10-16-2022, 08:32 PM   #25
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I am confused. Why would an inverter have a 240 VAC input? Is this inverter designed to backfeed the grid? If so, it seems like the wrong one to use in a RV or skoolie.
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Old 10-16-2022, 08:34 PM   #26
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It is described as having 240VAC input to run the battery chargers and to power it's split phase 120VAC/240VAC outputs and if wired so, 120VAC output.


What I don't like is I don't see an output wiring pattern for split phase 120VAC -- L1, N, & L2.
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Old 10-17-2022, 05:50 PM   #27
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Quote:
Originally Posted by Clouse House View Post
The all in one solar/charger/inverter I purchased is 240v splitphase input only. I'm only now realizing that it leaves me without the option of 30a shore power.
Growatt 8kW Split Phase SPF 8000T is the unit btw. Overkill I know, but it comes with two internal mppt controllers, and since I plan on running two different spec'd panel arrays, I thought it would be perfect for me.

Although we do plan on boondocking most of the time and I have a splitphase generator picked out as well, I'm concerned with the occasional camping site.

How often do you find that a campsite only offers 30a instead of offering 50a?
Do you think it would be worth me investing in an autotransformer as well so I can take 30a 120v and make it into 240v splitphase?

It also leaves you with no 50A shore power. I think that was mentioned in this thread but the point may have gotten lost. No properly wired park pedestal provides split phase power-what we commonly refer to as 240VAC, where there are two hot wires (180 degrees out of phase) and a neutral.

All power at RV Pedestals, whether 15, 30 or 50 amp, comes in one form only: 120VAC utilizing half of that split phase. No 240VAC appliance will run on RV Park power.

50 Amp dogbones do not give you two sides of that split phase, they are internally wired so they look like they provide split phase but they just make use of the one side of that split phase. That information is out there, but it's buried, and half the crap written on this topic on the web is just plain bad information.

No bus conversion should be wired for 240VAC panels or appliances. No RVs are wired that way. And by the way certain older 240VAC appliances are wicked dangerous regardless of whether your panel ground is properly isolated because they use ground for the return path.

https://www.skoolie.net/forums/f49/5...tml#post478371

If you MUST use 240VAC, you will NOT get that power from an RV Pedestal. You CAN get it from a generator.

It might be worth considering whether your initial investment into the 240VAC inverter is leading you down a path you ultimately may regret.
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Old 10-17-2022, 06:51 PM   #28
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Rucker, the input to the inverter has no neutral connection. The ground will be floating with respect to either Hot. If a 1:2 ratio transformer with the 2V side isolated is connected to the Hot1 and Hot2, because that is not referenced to a neutral, the inverter won't "know". A transformer will let them connect to 120VAC.


It's certainly worth asking the manufacturer.
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Old 10-17-2022, 09:21 PM   #29
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I do not wish to start a war of words with anyone about the 50 amp service one could connect to at an RV park. I think there are possibly a number of RV parks that have electrical grids that are not built to code. To satisfy my curiosity, I did a search on the net about 50 amp service at RV parks and found the following url that addresses this:


https://www.etrailer.com/faq-30-amp-...-adapters.aspx


Their description of a 50 amp service matches what I thought they are. If you connect up to a 50 amp service that has only L1 or L2 then potentially only 1/2 of your circuits will be live.


I have a device called a model 44290 surge guard that one plugs into a 50 amp service that detects and indicates correct or incorrect electrical power and protects against electrical surges.


Note that it detects if L1 and L2 are present, as well as open neutral, open ground, reverse polarity, etc.


I would look at the inverter in question to determine if it is UL listed and how many wires to connect to input power.
That's all I have to say on this matter.
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Old 10-18-2022, 01:26 PM   #30
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I do not wish to start a war of words with anyone about the 50 amp service one could connect to at an RV park.
Thanks Flattracker. It's not a contest, We're all just trying to get it right. Your interest in the topic and contributions are appreciated, and your post is an important correction to what I wrote.

Quote:
I think there are possibly a number of RV parks that have electrical grids that are not built to code. To satisfy my curiosity, I did a search on the net about 50 amp service at RV parks and found the following url that addresses this:


https://www.etrailer.com/faq-30-amp-...-adapters.aspx


Their description of a 50 amp service matches what I thought they are. If you connect up to a 50 amp service that has only L1 or L2 then potentially only 1/2 of your circuits will be live.
Thanks for this. That article helped. I still thought the point about phases on the two hot legs was fuzzy, so I dug in on the research (again) and I was definitely incorrect about the phase of each leg of power at the 240 Volt receptacle on an RV Pedestal. I was wrong!

Here's a link to the most definitive discussion I've found--I'm I was definitely mistaken when I said RV Pedestals have same phase legs! Thanks Flattracker for speaking up and carrying this discussion forward in the right direction.

Here's what appears to be the definitive wiring for 50 amp RV Pedestal: exactly the same as residential wiring, and NOT as I stated previously, same phase on each leg.
https://manuals.heartlandowners.org/...r%20System.pdf
And here is a wiring diagram for an RV Pedestal that similarly confirms the two hot legs for the 50 amp receptacle are 180 degrees out of phase-that is, just like a residential 240VAC receptacle:
50, 30, 20 amp Direct Burial RV Pedestal Electrical Box - RV Park Supplies

Where the same phase is on both legs it is either a miswiring of the pedestal, or the result of using a 3050 or 5030 dogbone.

So my previous statements about NOT wiring 240 appliances into a bus matter only in the event you plan on using (in particular) a 3050 dogbone. If you stick to places where there is a 50 amp service, you're fine; otherwise your 240 VAC devices will not work correctly. Things like the control panel or a drum motor of a dryer may work because the electronics are usually fed by one leg of power, but the high-draw components like heater elements or compressor motors will not.

One other point on this: it may be very corner-case, but if you wired in the old style three-hole 240VAC receptacle like a NEMA 10-30 (like old dryer receptacle), any device that uses that plug may also use the ground wire for their neutral, which can in turn electrify the bus chassis. No bueno. I think this point is important for bus converters because repurposing materials for a skoolie is intrinsic to the ethic, and repurposing an older appliances, especially one that comes with a big price tag new, might be more common in the community.
Quote:


I have a device called a model 44290 surge guard that one plugs into a 50 amp service that detects and indicates correct or incorrect electrical power and protects against electrical surges.


Note that it detects if L1 and L2 are present, as well as open neutral, open ground, reverse polarity, etc.
Nice product all around.

I took a look at the specifications and I didn't see anything that checks for same phase on both legs, so I'm not sure it would pick up this condition specifically where a pedestal is miswired and uses only one leg of the feed for both poles.

Fortunately, it's a simple check: use a voltmeter to measure the voltage between the two hot pins on the pedestal. It should read 240VAC. If you get a reading of zero volts, check each pin to the common and if you get 120 on both, the pins are likely wired to the same phase.

Quote:


I would look at the inverter in question to determine if it is UL listed and how many wires to connect to input power.
That's all I have to say on this matter.
I understand you may be reluctant to make an opposing statement, but I appreciate this post.

Hope this helps, and thanks again Flattracker for clarifying the record.
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Old 10-18-2022, 01:31 PM   #31
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Quote:
Originally Posted by TaliaDPerkins View Post
Rucker, the input to the inverter has no neutral connection. The ground will be floating with respect to either Hot. If a 1:2 ratio transformer with the 2V side isolated is connected to the Hot1 and Hot2, because that is not referenced to a neutral, the inverter won't "know". A transformer will let them connect to 120VAC.


It's certainly worth asking the manufacturer.
Thanks for this clarification.
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Old 10-18-2022, 01:31 PM   #32
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Quote:
Originally Posted by Rucker View Post
Fortunately, it's a simple check: use a voltmeter to measure the voltage between the two hot pins on the pedestal. It should read 240VAC. If you get a reading of zero volts, check each pin to the common and if you get 120 on both, the pins are likely wired to the same phase.

That is 100% correct.


The input and output wiring for their inverter is above. It has no neutral connection for incoming 240VAC.
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Old 10-19-2022, 03:27 PM   #33
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Why combine the inverter and charger? If you already have a charge controller for your solar panels, then why charge your batteries with your inverter charger by a different set of rules than the ones used by your charge controller? An inexpensive AC-DC power supply can use the same charge controller as your panels. That way the batteries are always being charged by the same set of rules. If you have separate units, and one fails, you only need to replace one thing. Combination units are much more expensive.
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Old 10-19-2022, 03:58 PM   #34
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So here's my setup:
  • 2 x 2000w Solar arrays feeding Growatt inverters (1 array on the bus, another on a pedestal)
  • 240V/50A RV plug
  • 120v/60A Lithium Battery Charger

In fall and spring, I use almost exclusively solar. In the dead of winter or dead of summer, I usually plug into the 50A RV plug to supplement the use of my heater/air conditioning. I have a dual zone 240v mini-spit in mine. Finally, if I need to supplement the solar without access to a 240v/50A plug, I can use the 120v battery charger in any household 15A outlet or in my generator (a 3500W Predator from Harbor Freight).

This has been working out for me for the last year just fine! Hope that helps!
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Old 10-20-2022, 10:26 AM   #35
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Quote:
Originally Posted by Clouse House View Post
The all in one solar/charger/inverter I purchased is 240v splitphase input only. I'm only now realizing that it leaves me without the option of 30a shore power.
Growatt 8kW Split Phase SPF 8000T is the unit btw. Overkill I know, but it comes with two internal mppt controllers, and since I plan on running two different spec'd panel arrays, I thought it would be perfect for me.

Although we do plan on boondocking most of the time and I have a splitphase generator picked out as well, I'm concerned with the occasional camping site.

How often do you find that a campsite only offers 30a instead of offering 50a?
Do you think it would be worth me investing in an autotransformer as well so I can take 30a 120v and make it into 240v splitphase?
Most campgrounds have 30A service, but not all have 50A service. You can make an adapter for your shore power cord that connects the two hot legs of your 50A connector and plugs into your 30A socket. Not a problem when you have a location with only 30A service.
A lot of state parks only have 30A service.
Another route you can take is in your service distribution panel. We have both 220 split single phase inverter and a single 110v inverter in our redundant system. If the primary inverter fails we can switch to the backup. When we do that, there is one breaker in the panel the is normally in the off position. It ties both hot legs together and converts the panel from split 110 to single 110.
If you do it this way be sure to paint the special breaker red so you remember to turn it off when you are on your split inverter.
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Old 08-11-2023, 11:21 PM   #36
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Solved 30A 120V primary to 120V/240V split pase secondary.

Quote:
Originally Posted by Clouse House View Post
I'll look on eBay but, neither of those items do as needed. If the charger only works with 240v split phase and the only available hookup is 120v. Then I need a separate device that can charge my battery off of 120v like fo4imtippin suggested. Or a transformer that goes from 120v to 240v split phase like Victron makes, and after researching more over the past 24hrs I'm kind of leaning towards going with the Victron unit.

The two links you provided go from 600V to 240v split phase or 240v split phase to 120v. But I did not think to check eBay for a deal on a 120v to 240v split phase transformer so thank you for that. Maybe I can find one cheaper than the Victron unit.
Spent a bunch of time calling and emailing different distributors of transformers. When I found any that had the capacity that we needed in our rig, they were more expensive than the Victron 32A Autotransformer.

32A is per leg of the secondary. They do make a 100A Autotransformer as well. The good news is that you can do a 30A shore power 120V to split phase 120v/240v

It is important to know that no just any transformer configuration will do.

There is a difference between split phase and single phase 240V. Single phase 240 cannot be split into two 120V legs. With split phase, each of the 120V legs are 180 degrees out of phase with each other.

We did accomplish this with a Victron autotransformer as the input of our EG4 Hybrid Inverter/MPPT Solar controller. It works great. The EG4 behaves as if it is grid tied and does the backup UPS function without a flicker of the lights.
We are running air conditioning and cooking with induction as well as refrigerators and deep freeze.

I have included a diagram for use with a Hybrid inverter and for use without an inverter for those who want split phase with their 30A shore hook up but don't have solar.
Attached Thumbnails
120-120 240 split phase.jpg   120-120 240 split phase service panel.jpg  
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