split phase Image

split phase

Dual Multiplus 12/3000 in Split Phase Running on Single Phase

Hi folks,

I'm new to the forum but have been looking for an answer. I have two Multiplus 12/3000 inverters with a Venus GX (and additional Victron solar items as well) in a motorhome. These were all purchased in last 90 days or so, so fairly new hardware. The motorhome is wired in split phase and everything works 100% of the time when i'm on a 50amp standard USA RV service. My setup also cuts over to my QD1000 generator flawlessly and everything works fine.

My issue is when i'm plugged into a 30amp single phase plug. When I am, I understand normal operation "should" be that my master inverter will invert and charge the battery and my slave inverter will simply invert. This is a Victron limitation on single phase power as i understand it which is fine. My question is. When i'm plugged into a single phase 30amp plug, neither the master nor slave inverter will recognize the AC input. The input shows in the Venus panel as there on both legs (single phase on both legs because of the 50a to 30a dogbone adapter that pairs the single phase 120v to both legs) but the units will not initiate a charge, its basically like i never plugged anything in at all. See attached screenshot. Any advice on what setting may be causing this to occur? I'm fine with only one inverter charging, i just need to understand why thats not happening..



Any helps or advise would be greatly appreciated.

epm96 asked
sv-k answered ·

3 Answers

Using AutoTransformer to create 120v/240v split phase from single phase 120v input

I have a use-case for the AutoTransformer that is different from what I see generally discussed. I want to use it in my RV to take in 120v 60 Hz from either my Onan Generator (2 separate 120v legs that are SAME phase) or the shore power inlet (30/15 Amp which are 120v 60Hz single phase). I have those 2 inputs going to an automatic transfer switch so whichever one is "on" will pass through to the AutoTransformer. I would like for the AutoTransformer to step up the voltage from 120v single phase to 120v/240v split phase. I will then pass that split phase into the input side of my dual inverters (one inverter for each 120v leg) so that when I have a single leg input, I still get both inverters charging instead of one side passing through voltage and the other rejecting the phase and inverting to make the "correct" phase.

So, my question is, how should this be wired up to the inverter. It has labeled "input" and "output" sides but the "input" side only has 240v Line and Neutral labeled connectors. The "output" side has 120v Line 1, Neutral, 120v Line 2 connectors.

My intuition tells me to disregard the input/output labeling and connect my source 120v power with:

source 120v Line > AutoTransformer "output" Neutral

source Neutral > AutoTransformer "output" 120v Line 1

Then my output would be the 240v wave form stepped up via transformer as measured between the "input" Neutral and "input 240v Line connectors. I would need to carry over the neutral from the other side to provide 120v/240v split phase.

It is this last part I am unsure of and need some guidance on.


Diagram attached of my planned whole system that hopefully makes clear what I am trying to achieve.


cookinwitdiesel asked
natebert commented ·

2 Answers

Multi+ Duplicating Watts readings on a 230v Split Phase with Autotransformer

Hi Victron,

I live in Central America where we use the US Split phase grid system, I have a ESS system with:

- 1ea Multiplus 48/5K/ 230v

- 48v Lifepo4 Bank 450ah

- SmartSolar MPPT 250/100 rev2

- AutoTransformer 32amps

Note: the system does not feed to the grid.

I have setup my system as per Auto-transformer manual advice for Split Phase systems as below:


I have noticed from the beginning of my setup a drastic Watts measure change when Grid goes out and I already read your article here https://www.victronenergy.com/live/ccgx:ccgx_faq including the Q6.

But My case is in my opinion more drastic reading difference.

This is a normal Watts reading with Grid power:

- My home consumption says: 1016W

- Battery charge current: 48.6Amps (2452W)


Right after I open or disconnect the Grid:

- Home Power consumption: 480W (Half reading). I confirm No changes in the Real home Load equipment.

- Battery Charge Current: 58.8A (2971W) Yes the MPPT generation increases in that moment 100W but that does not justify the 500W (10Amps) Battery Charge increment. Looks like the increment in charging is due to the decrease in Loads need by the Multi+


The behavior is telling me that for some reason having a 230V Multi connected to 2 Live power lines (L1=120v + L2=120v), the Multi is duplicating the reading in the ACin/ACout side and direct affecting the battery charge performance. Since this 230v Multi+ is designed to connect L1=230v + Neutral. I think this Multi+ is not properly reading 2 live phases L1 + L2 correctly, instead it is duplicating the reading.

I have done other testing with a 3rd party watts reading and the reading is half lower than Multiplus AC Loads reading and that make me think my suspicious is correct. Can Victron staff please confirm my situation here?

I know that an option here is to get the Carlo Gavazzi meter for better reading, but I will like to ask if Victron can do a Firmware adjustment for customers that use their 230v Multis in US market before expending more money.

@mvader (Victron Energy)

Thanks a lot

Yusef Neblett asked
edgardogarcia answered ·

7 Answers

Multiplus design review - pseudo split-phase operation



Hi Everyone, I've found a few variations of this already answered but I there were some pieces I'm still not clear on. The topics were very old so I thoguth best to ask it again.

I have an RV with 50A / 240V service. Everything in the RV is 120V, the 50A service feeds each side of my panel with one leg of the shore power. In the event a 30A service is the only thing available, a 50A to 30A adapter will simply bond the two hot legs and feed them from the same 30A leg. In this case, I just need to be cautious about power consumption.

I'd like to install a couple MultiPlus 3000/24 inverters in a configuration where I have one feeding each side of my panel. I realize this isnt the best utilization of unused capacity but from what I'm able to deduct, it will yield the most flexibility with shore power configurations.

Attached are two drawings depicting a 30A and 50A situation. Both pictures also show a future 3rd and 4th inverter to increase capacity.

My questions are:

  1. If I leave inverter 1 & 2 as independent units, will they care or recognize the power coming in to each is in phase or 180* out of phase from each other? They shouldnt, right?
  2. If I add Inverter 3 & 4, would I just team then to 1 & 3 respectively?
  3. Are there any concerns with multiple inverters working independently of eachother over-charging LiFePo4 batteries?
  4. Any other considerations I may have missed?

Thanks guys!

ssybert asked
ssybert edited ·

3 Answers

Autotransformer voltage outputs are different

I am having an issue with the Autotransformer output voltages - 114V on L1 and 120V on L2 (with no load)

120V current is supplied by a Quattro 48V / 10000 / 140-100/100 to the 100A Autotransformer. I'm using the AT to provide a split-phase 120/240v supply to the 50A main break panel in my RV

I have wired the AT connections according to the diagram #3 shown on the system schematics page from the Victron website: (https://www.victronenergy.com/upload/documents/AT-3-split-phase-120V-to-120-240V-with-Quattro-120V.pdf)

The Ground Relay in the Quattro is set to ON and is correctly grounding the Neutral to earth.

Here are the voltages I read at the terminals:


The problem I have with this is that the voltage on L1 decreases a lot with load, and when occurs equipment will pull more current to compensate for the lower voltage.

Here is a pic of my RV control panel, showing the disparity in voltage between L1 and L2. Even though there are 2 air conditioners on Line2 it has only dropped 2 volts - Line1 dropped from 114v to 105v. This can't be good.


Questions: 1) - Is this method of wiring correct, and 2) what is causing the voltage discrepancy?


Aug-31: Editing this in an attempt to make the question visible again. I'm thinking of sending this AutoTransformer back to Victron as it is not performing to expectations. I have seen voltages as low as 96 volts on L1, at which point my UPS shuts down my computer, and various other circuits shut down. Not happy...

I'd appreciate a comment from anyone who has had experience with an AutoTransformer.


Pete MacLachlan asked
irwinr answered ·

5 Answers

Quattro's in Split Phase connected to 120v input

Below are the details of my installation:

Product Quattro 48/5000/70-2x100 120V

Firmware version 424

Product id 2753

VE.Bus connection VE.Bus

Hardware configuration Two units configured as 120v/240v split-phase

I went with this configuration for my Motorhome RV based on the advice of Victron that when connected to 30 amp RV service (Which is only 120v) the inverters would support this by having only the master inverter connect to the 120v source and the secondary inverter would remain in "inverter only" mode. I tested this out on some 120v outlets and found that it worked fine at the time. 50 amp service is no problem because 50 amp RV service is 240v split phase which allows both inverters to connect to the AC source.

However I recently tried to plug into a 120v outlet because my motorhome is in the shop (No sun for solar charging) and my batteries were getting low and desperately needed to be charged. I plugged into a 120v outlet at the shop and the lights on both inverters just flashed back and forth at me. No warnings or errors were displayed on my Color Control GX. I didn't have my laptop with me to connect directly to the inverters to see if that offered any more insight.

I haven't made any configuration changes to my knowledge that would affect the inverters phase split configuration, so I'm a little puzzled about what the issue might be. It's been so long since I set this up I don't even remember where in the configuration you can configure it to allow only a single inverter to connect to a 120v source when in a 240v split phase configuration.

The motorhome is still in the shop so I'm hoping I can get some ideas of exactly where to look to identify/fix before I go back and try again to get the batteries charged.

irwinr asked

0 Answers

Search Mode for four Multiplus II in parallel + split phase (2+2 configuration)


I am looking at purchasing four multiplus II 48/3000/35-50 120v to put in a 2+2 configuration -- 2 parallel unites on each phase of a 240v split phase. I'm primarily going this route over a larger 230v Quattro + autotransformer due to the significantly lower zero load draw (52w for 4x mutiplus II vs 110w for a 15kva Quattro).

With low power consumption in mind, I can't find a clear answer to whether or not parallel / split phase muliplus II units can be configured to go into search mode under zero load conditions. This would bring my standby power draw down to 12w which would be excellent.

I know the manuals state AES mode does not work in a non-standalone configuration, but what about Search mode?

yld asked
yld edited ·

2 Answers

Split-phase boat power system with MultiPlus-II 2x120 and Autotransformer

TL;DR: I want to build a system that can take in split-phase 120/240VAC, single-phase 120VAC, or 12VDC, and always output split-phase 120/240VAC. I have a potential solution in mind using MultiPlus-II 2x120 + Autotransformer. Will it work? Are there better options?


I have a boat with a split-phase 120/240VAC system. Normally the two phases come from either 120/240VAC shore power, or from a split-phase generator. I'm considering an inverter setup that would allow me to create both legs from the inverter, and am imagining the following system:

Connect a MultiPlus-II 2x120 to the split-phase system. When the generator is on (or split-phase shore power is connected), it will pass through both legs. When single leg shore power is connected, or no input is provided, it will yield only single phase 120VAC.

I want to then connect the output of the MultiPlus to an autotransformer, such that:

  • When the generator or split-phase shore power is being passed through, the autotransformer balanced loads between the two legs.
  • When only single phase 120VAC is available, the autotransformer will convert it split-phase, creating the second leg.

Is such a configuration viable? Is it possible to wire the autotransformer in a way that achieves both of these purposes?

An alternative is just to use an 240VAC inverter with an autotransformers, but that seems to have the problem that it won't work when only single-phase 120VAC is available from shore power. Is there a workaround for that other than installing another transformer?

EDIT: Added diagram for clarity.

resistor asked
Kevin Windrem commented ·

1 Answer

I'm wanting to install a system on my boat that has 240v split phase panel

I would like to install an inverter on my boat to use while underway and at anchor so I don't have to run my generator all the time. My boat has a 240v split phase panel. The only appliances running on the 240v side(using both legs) are my A/C units, my clothes dryer, and my water heater. I THINK I can use the Victron Multiplus ii 2x 120v to power the two legs for use with 120v breakers and turn off the 240v breakers while underway but if I'm understanding the Multiplus correctly I would have issues still while on shore power with pass through because of the two phase side of things.

Am I understanding this correctly and one multplus would not work? If I used two would I really need the 2x 120v considering that would make 4 120 volt legs when I only need two and is there a better alternative if I am using two inverters communicating with each other to make split phase?

skot0123 asked
basil katakuzinos commented ·

1 Answer

Split Phase dual Multiplus with generator

Hi all,

I could use a little help planning my setup. I have a pretty standard US configuration in my RV 120v/240v split phase. My mini split AC is 240v so I need 240v. I have a 12.5kw Onan that says 120v/240v 1 phase *picture attached*. I would like to put in an inverter system but I'm pretty confused about what functionality is possible.

Ideally I would like everything to passthrough the inverters. Generator, 50A 240v split phase shore power, 30A-15A 120v single phase all passing through the inverters so I can utilize the charger and power assist features of the multiplus's.

My current understanding is that I will need 2 Multi's and 2 autotransformers. One autoT to balance the genset and one to balance the inverters but I'm not sure exactly how to hook them up. Where my understanding really stops is at the single phase input. How do I add the ability to charge from 120v hookups without a separate bank of chargers?

Thanks for any help!


exmoso asked
exmoso commented ·

1 Answer

Autotransformer step down split phase to single phase

With the 100amp autotransformer, stepping down 240 split phase to single phase… 2 questions… is the single phase output capable of 100amps if the 240 in is 2 legs of 50amp? Also, if I drop a phase (RV setup, say using a 30 amp adapter which only brings in 1 leg of 120) does it effect anything or will it still just put out it’s 1 leg?

whynotrv asked
whynotrv commented ·

1 Answer

Multiplus II 5000va Split Phase 220v On-Grid Setup

I am seeking feedback on whether a 220v single phase Multiplus II 5000va is able to synchronize and work "on grid" with a 220v-240v split phase grid (L1+L2+G. NO NEUTRAL). There are no 110v loads or panelboards, all are 220v loads connected Line-Line.

The intention is to use the Multiplus synchronized with the grid together with an energy meter/export control to allow backflow of power to other loads and the utility.

I have successfully used a multiplus1 5000va with 220v split-phase generator through the input however this was off-grid, not synchronized, using the genset input to power the loads and charge the battery.

A picture of the grid service is below.

Appreciate any comments or feedback!


raftoda asked
shaneyake commented ·

1 Answer

EM24 RS485 on 120/240V split phase loses its settings

We set the EM24 meter to mode E (application E?), split phase 120/240V. ESS mode operates fine (i.e. the inverters feed power upstream without feeding power into the grid), but the meter loses its settings, but after a few seconds, it looks as if the Venus changes the settings of the EM24 to three phase and the system starts to behave erratically.

Roberto Kruse asked
Roberto Kruse answered ·

1 Answer

Can two 100A autotransformers be connected in parallel for a 200A split phase output?

Hi VE Experts,
Can two 100A autotransformers be connected in parallel for a 200A split phase output? The system will have two Quattro 15000 240V units. This is for a 240/120V, 50Hz system so we cannot use two 120V Quatto units in parallel as the 120V is only for 60Hz output.



lalith asked
lalith commented ·

1 Answer

Wiring diagram for Quattro split phase with autotransformer?

We have an off-grid system with two 48/10000 Quattro inverter/chargers configured for split phase, with a battery bank and solar chargers. We also have a generator feeding the Quattros on AC input 1 when the batteries are low and the sun is not shining. We have a few 110 appliances that consume significant load, causing the legs to become unbalanced.

I'd like to add a 100 amp Victron autotransformer between the Quattros and the breaker panel so that we can balance the legs, especially when the generator is running.

The autotransformer manual has a wiring diagram for balancing two inverters in split phase, but it's not very specific -- it's more conceptual than "connect this to that". The manual also says "split phase output balancing may require some more attention", but never goes into more detail on how to do it. Does anyone have a more specific wiring diagram for balancing two Quattros with the 100 amp autotransformer?

Also, the Quattros open the ground relay when the generator is running. I've wired that up to the autotransformer so that it will drive the autotransformer ground relay. However when the Quattro is powered by the generator the ground relay is opened, which I don't think I want to happen -- the autotransformer ground relay should always be closed, as far as I can tell. Does anyone have any tips for forcing the autotransfomer ground relay to always stay closed?

half-moon-bar-lodge asked
GARY WILLETT commented ·

1 Answer

Autotransformer wiring for balancing loads, split phase 120/240

My AC source is split phase120/240. It supplies two hot wires and a ground, no neutral. I am using a Victron transformer because I am splitting the two phases into two separate battery chargers for my RV, but I need the loads on the two hot wires to remain balanced. My question is, would it be correct to connect the two hots AND the ground into the autotransformer, and then use the two 120 lines, the new neutral (created by AT), and ground coming from the autotransformer to connect to my loads (battery chargers)? Any potential issues with that set up?

brianv asked
wkirby answered ·

1 Answer

Autotransformer output capacity

I am confused as to what the actual output of the autotransformer 32 and 100 amp is. I see that the neutral caps out at 32 amps on both. So does that mean that the total output of either autotransformers is 3840VA in split phase 120/240? It doesnt make sense because if you are connecting let's say two 120v 5000VA Quattros to the AT to create balanced split phase current, you basically lose a bunch of output capacity. Or is the 100 amp version able to output 100 amps total between the two 120 lines?

brianv asked
wkirby answered ·

2 Answers

24v DC supply shuts down when inverter state of charge gets low


Help would be much appreciated.

We have a Quattro 5000 120 in our camper.

Sockets etc are ran off the victron but a separate mains control is used for lights and water pump.

I think the victron dictates what happens with this also.

The victron is at 65% power and this mains control just died. So sockets and fridge etc working but not the lights or water pump which are obviously important.

Does anyone know if a switch or relay may have kicked this mains off (Maybe a 24v mains)?

How can it be reset? I am a novice but I guess there is split power switch or setting that has kicked the 24v (I think the lights and water pump are 24v).

When we first got the vehicle the victron was badly set up and the 24 v power was killed when the battery’s were below 90%.

This was reduced to 20 or 30 but maybe it has reset somehow?

I need to be able to get the lights and water work pump working but have no clue how to get the victron to enable them again.

Please help. Many thanks

stepheng asked
seb71 answered ·

1 Answer

Split phase with two 120v Quattros and 5500 onan genset 30 amp each leg in an Rv configuration

I have two quattros I am going to setup as primary and Secondary/slave. I believe my 5500 watt onan is split phase 180 degrees out for 120/240.

Do I need a transfer switch if the genset is connected to ac-1 input on both quattros?

I would like to wire the quattros with each leg from genset to each Quattro along with each leg from shore power to each Quattro.

just want to make sure the transfer switches in the quattros can handle the transfer between shore and genset without an external transfer switch…

thx for any input

Geoffrey Schwark asked
Kevin Windrem commented ·

2 Answers

Split Phase System Configuration Advice

Need some advice on my setup please. The system consist of the following:

2- 48v 3kVA Quatros

50 amp 120/240 Split Phase Shore Power

7,500 Watt 60 Amp 120v Single Phase Generator

Cerbo and a bunch of solar ect...

The system is configured in 120/240 split phase with the shore power L1 going to the master Quatro AC-2 input and L2 going to the slave Quatro AC-2 input. The generator simply goes to AC-1 input on the master Quatro with nothing connected to the slave Quatro AC-1 input. This setup works fine but its a little lacking when running the generator when the batteries are low. I never see much more than 3,000 watts from the generator and the batteries don't see much of a charge when the slave Quatro has a load on it. This causes the generator to run hours on end not charging the batteries. Spending 12K on a new 240v split phase generator is out of the question. We need to keep the split phase for the 240v appliances onboard. Will a Victron auto transformer between the generator and inverters work for me? Or maybe two transformers so I can stack the inverters.. One after the shore power, 240v to 120v to stacked Quatros and then another transformer to get split phase off the Quatros. Any advice would be great thank you.


burnscraft asked
Kevin Windrem answered ·

1 Answer

Suitability of 2 x multiplus 3kVA in split phase configuration to run 1 HP pump

I've asked this question through a dealer channel but no response from Victron for over a week so hoping I can get an answer here.

I have a 115/230V 1600w jet pump in an off-grid application. I'm considering using two Multiplus 3kVA units in a split phase configuration to run the pump at 230V.

The concern is whether the Multiplus system can handle the inrush current of the pump.

The pump starts and runs fine with my 5kW 240V generator, and using a clamp meter I measure 34.5A of inrush. That's 8280W of surge.

According to the Multiplus specs, a 3kVA unit can handle 6000W of surge. With two units in a split phase configuration that provides 12000W of surge.

It appears there is suitable headroom to do this but I'd like some assurance before moving forward.

Is my math correct? The other unknown is how long of a surge the Multiplus unit can handle.

And if it does handle it, will a warning be generated every time the pump starts?

Thanks for any advice!

adombek asked

0 Answers

US-spec split phase 240V appliances on Victron single phase inverter

I’d like to run US split phase 240V appliances (such as induction cooktop or oven) directly from a Victron single phase inverter. These are 3-wire appliances, expecting two hots and a ground but no neutral. Will an autotransformer be required or from the perspective of the appliances is single phase and split phase the same thing.

banana asked
Barry Timm commented ·

2 Answers

split phase 240v INPUT to Quattro 230v

I have a 230v boat. with a Quattro 5K inverter charger. If I am in the us and have 240v split phase shore power, can it be safely connected to the Quattro using shore L1 (120v) and L2 (120v) which is 240v between them. Connected to Quattro input 1 L1 and Neutral?

I know that I can safely do this with all systems onboard using Shore L1 and L2 to Boat L1 and N without having the Quattro inline. What I am not clear on yet is if having the Quattro inline is an issue?

Theoretically, the Quattro shouldn't care.

I would appreciate a definitive answer on this. Would be an expensive experiment if it went wrong!

mixman1 asked
Kevin Windrem edited ·

2 Answers

240v AC single phase to 120/240 split phase


I have 240v AC input 50hz (European) input and I need to have split phase 120/240v 60hz for a clothes dryer. (as per diagram 14-50R plug)

Would this transformer work for this application.

****This dryer as most North American units uses 120v ac for timer etc. and 240v ac for the heater element****



luminavanman asked

0 Answers

Single Quattro for one side of split phase

Would it be feasible to add a single Quattro or Multiplus (not the 2x120v) to provide one half of a 240V split phase (North America 120/240V residential power) while taking the other phase directly from my main panel and passing it through along side?

I’d like backup/UPS for the equipment but would move lighting to the non-inverter phase. I’d also like to add a 30A 240V that wouldn’t be powered during utility outages (for car charger or brewing setup, I guess this is the trickiest part, and I could skip it).

Is there a reason it would be inadvisable to use an inverter on only one phase? If it’s okay, what extra considerations should I make?

owenfi asked

0 Answers

ET112 Energy Meters Two for Two phase

Can we use two ET112 Meter to measure grid input on a 2 phase site? We have them in stock already. We have set them up but we cant seem to assign one to L1 and one to L2 because they seem to be locked in a 1 phase convention.

David asked
markus answered ·

1 Answer

Onan 8000 generator single phase (two circuits) connection to 2 Multiplus chargers?

For my RV application, I have a transfer switch with both shore power (50A) and generator power (Onan 8kw) as input. The shore power is normal 2-phase 240V, while the generator output is 2 30A single phase circuits.

I don't need 240V in my RV - everything is 120v. Is there any reason I cannot connect each leg of the transfer switch output to a separate Multiplus inverter/charger? When on shore power, the 2xMultiplus inputs will be 180 degrees out of phase. While on generator power, they will be in phase.

At this point, I am not planning any passthrough loads - all loads will come from the inverters.

oceanos asked

0 Answers

MultiPlus 120V Shore power, 240V Load?

I am looking at using two Victron MultiPlus (24/3000/70-50 120V PMP243021102) inverters to supply 240V Split Phase power. Can I get a 240V Split Phase output (120V from each inverter and 240V across both inverters) when my input (Generator or shore power) is only 120V single phase?

davem asked

0 Answers

L2 On Grid showing Negative power (2x Quattros Split Phase + AT)

SOLVED - (See comment below) I am having a strange issue on my new Victron Quattro setup. I am seeing a negative number on my grid current. The AC loads side is also incorrect. I am running 2 Quattros and an Autotransformer wired exactly per this guide: https://www.victronenergy.com/upload/documents/AT-4-stacked-inverter-2x120V-to-120-240V-with-2xQuattro-120V-REV-B.pdf

Any suggestions? I have connected the GND Relay, changed the dip switch and have confirmed it is switching the relay on the AT. Ground Relay is disabled in both Quattros

Everything works perfectly when Inverting. The AT is balancing L1 and L2 perfectly. This strange issue is only showing up on shore power.

The attached photo is with the main breaker off after the AT (No Loads)


jetwire asked
jetwire edited ·

1 Answer

Using a Quattro 48/10000 230V with Autotransformer in US residential 240V split phase

I was originally asking about design consideration between using one large inverter or two smaller inverters. Then got onto a bit of the design using one large inverter, but that wasn't really pertinent to the Subject for tha thread.


So I'm re-asking the one-inverter-autotransformer question here in a dedicated thread. Has anyone set up a 230V Quattro with Autotransformer in a US residential setup ?

I'm envisioning a setup as follows :

  • Main panel : 100A breaker to Quattro AC1-in
  • Main panel : 100A breaker to sub-panel 100A breaker with interlock
  • Quattro AC1-out to Autotransformer
  • Autotransformer AC-out 120-0-120 hot-neutral-hot to sub-panel 100A breaker with interlock

The interlocked breakers are a back-feed setup for the sub-panel. Only ONE breaker can be on, the other must be off. So the sub-panel is fed by EITHER the 100A from the main panel, OR the AC-out from the Autotransformer. For example


In the US, there can be only neutral/ground bonding point, it must in the main service panel. So the GND relay in the Quattro should be disabled, and the GND relay in the Autotransformer should also be disabled. This way, regardless of whether the sub-panel is fed from the main panel or from the Autotransformer, the neutral/ground bond will only be in the main panel.

The created neutral from the Autotransformer is connected to the neutral bar in the sub-panel, which connects to the neutral bar in the main panel, where the final neutral/ground bond is made.

During an outage, power to the Quattro comes from a 240V generator, using only the L1/L2 hot legs. The neutral is not connected, so it acts just like the connection from the main panel.

Does this all make sense ? Is it correct for a US residential install ?



halfwalker asked
henry-cabrera answered ·

3 Answers

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