Use RV inverter as generator for house

[jameshowison]

House has a generator inlet with interlock switch.

RV has a 3000W Victron inverter with sufficient batteries/wiring to provide sustained 25amp of 120v.

What do I need on the RV to enable connection to the generator inlet, to provide emergency power to the house?

Two issues:

1. AC panel in PV is full, I don’t want to rewire it. All outlets are GFCI protected.

2. RV inverter produces 120v AC. House generator interlock is 240v. I don’t need to power any 240v loads in the house. But I would like to power both sides of the panel with 120.

For the 120 to 240v my understanding is that I can provide same phase 120v to both hot pins on a SS2-50r 240v generator cable. 240v stuff will be off, but would see 0v differential between the hot pins. Currently I’m doing this with a SS2-50r (female) to TT-30p (male) “dog bone” adapter from Amazon Flameweld Generator Adapter Cord https://a.co/d/ckNy1Lp

I plugged that into a house outlet (using a regular outlet 120v 5-15p to TT-30r) and confirmed that 120v on both hot pins (to neutral and ground) but 0v between the hot pins.

However when plugging into the RV I only have GFCI 15amp outlets. With the generator inlet still off, if I connect the 15 amp outlet to the generator inlet, the GFCI instantly trips.

I don’t know whether that is caused by the 120 to both hots or the house having a ground to neutral bond. My understanding is that the Victron does not connect ground and neutral, unless the RV is being charged from the incoming shore power connection (which I don’t have connected to the house at present!)

At the RV end, I think I want the equivalent of an RV park pedestal. Ie a TT-30 outlet protected by its own circuit breaker (here I’d probably use a 25amp to reduce overloads on the inverter when the house was connected). I’m thinking of wiring that between the inverter and the RV panel, using a DIN railed mounted circuits breaker).

Basically that would give a non-GFCI outlet from the inverter for the generator cable to plug into.

Sorry for wall of text!

 

[hwy17]

RV inverter produces 120v AC. House generator interlock is 240v. I don’t need to power any 240v loads in the house. But I would like to power both sides of the panel with 120.

There is a potential problem there if you have any MWBC's, feeding both legs of an MWBC with 120v in phase can overload the neutral.

They have been more or less popular across different time periods and areas. Usually found in the kitchen. Almost always fed by the red and black wire of a 12/3 or 14/3 romex cable. The breaker handles are supposed to be tied nowadays, but that's not always the case.

 

[jameshowison]

There is a potential problem there if you have any MWBC's, feeding both legs of an MWBC with 120v in phase can overload the neutral.

They have been more or less popular across different time periods and areas. Usually found in the kitchen. Almost always fed by the red and black wire of a 12/3 or 14/3 romex cable. The breaker handles are supposed to be tied nowadays, but that's not always the case.

Thanks. Confirmed we do not have any of these. House was completely re-wired a few years ago.

 

[justinm001]

Use the 2nd output on your inverter and put the same outlet your RV uses (50 or 30a) then put the plug on your house. When in normal operation you run the power from house to inverter but if powers out you just flip the cable and plug from rv to house. If you have an rv genny this makes it even better.

I have this setup but have split phase (or will) so get 240v in and out.

Also 30a isn't much power so I'd wire up your disconnect to just 1 leg of your panel and move your breakers so only important loads are every other half.

You then can set a rule to turn off the 2nd output on the MP when battery is below 20% or so just so you have a bit of power left for the rv

 

[FloaterBoater]

Use the 2nd output on your inverter and put the same outlet your RV uses (50 or 30a) then put the plug on your house. When in normal operation you run the power from house to inverter but if powers out you just flip the cable and plug from rv to house. If you have an rv genny this makes it even better.

I have this setup but have split phase (or will) so get 240v in and out.

Also 30a isn't much power so I'd wire up your disconnect to just 1 leg of your panel and move your breakers so only important loads are every other half.

You then can set a rule to turn off the 2nd output on the MP when battery is below 20% or so just so you have a bit of power left for the rv

I'm not an expert in North American electrics, but wouldn't you'd also need to isolate the house from the grid when using the inverter in this way to prevent back feeding current and creating a safety risk to technicians working on the lines?

 

[jameshowison]

I'm not an expert in North American electrics, but wouldn't you'd also need to isolate the house from the grid when using the inverter in this way to prevent back feeding current and creating a safety risk to technicians working on the lines?

Yes, the generator interlock does this. The breaker for the generator inlet can’t be in the on position without turning off the main breaker to the grid. That’s all code compliant

 

[richard cabesa]

We don't live in an area that has frequent storm related power outages. Mostly SCE power down situation due to wind and wildfire concerns. I have a big enough battery bank and solar in the RV to run my two refrigerators. I can light the gas stove with a lighter. Battery powered lights

I skip the complexity of any direct tie in and just run a couple of cords for the refers to the RV when needed.

just another option

 

[jameshowison]

Use the 2nd output on your inverter and put the same outlet your RV uses (50 or 30a) then put the plug on your house. When in normal operation you run the power from house to inverter but if powers out you just flip the cable and plug from rv to house. If you have an rv genny this makes it even better.

I have this setup but have split phase (or will) so get 240v in and out.

Also 30a isn't much power so I'd wire up your disconnect to just 1 leg of your panel and move your breakers so only important loads are every other half.

You then can set a rule to turn off the 2nd output on the MP when battery is below 20% or so just so you have a bit of power left for the rv

I like the idea of flipping the cable! Would need a locking 30amp to locking 50amp, but that’s easy to get. And TT-30 female on the side of the RV somewhere.

I don’t think I can use the second AC out in the Victron because AC-out-2 is always disconnected when grid power is not available on AC-in (which is definitely won’t be in a power outage at the house . At least that’s what the manual and some threads on Victron community say.

I’m still mystified by the GFCI outlets flipping as soon as connected to the generator inlet (even without the inlet circuit breaker turned on). Anyone know why that is happening?

 

[justinm001]

I like the idea of flipping the cable! Would need a locking 30amp to locking 50amp, but that’s easy to get. And TT-30 female on the side of the RV somewhere.

I don’t think I can use the second AC out in the Victron because AC-out-2 is always disconnected when grid power is not available on AC-in (which is definitely won’t be in a power outage at the house . At least that’s what the manual and some threads on Victron community say.

I’m still mystified by the GFCI outlets flipping as soon as connected to the generator inlet (even without the inlet circuit breaker turned on). Anyone know why that is happening?

Out2 is off by default unless shore is connected. Use veconfig and virtual relay to turn on out2 all the time or on when SoC is above x%

GFCI doesn't work on panels because of the ground. I believe they trip when the hot wattage doesn't equal the neutral wattage so it blows. Using a panel with neutral and ground bonded causes the neutral and ground to share the load.

 

[zanydroid]

AFCI will most likely flip too unless they are the type where neutral does not flow through the breaker. Most do have neutral flowing through, but not all. They do all need to be powered by neutral though

 

[HarryN]

I am not certain, but I think if you use an auto transformer, it can take in the 120 vac output of your inverter and convert it to split phase 240 vac for your panel.

Another possible alternative is to have the critical loads moved to one side of the panel and have the other not powered.

As a practical matter, with a V 3000, it is a 2400 watt real world inverter. We are talking about running the refrigerator and 1 kitchen appliance at a time. Perhaps map out what outlets and lights will actually work if just one side of the panel is active and see if that will be sufficient.

 

[Vigo]

Given the limited inverter output i also think that just rearranging all critical loads to one leg and leaving the other dead is probably the simplest approach.

You could also do the autotransformer idea but again, given the limited output of the inverter I'd probably skip that mess because not many 240 appliances would run on that size of inverter to begin with.

 

[HarryN]

As far as the GFCI tripping - it might be that there is a G-N bond in the RV and you have it also connected to the service panel which has it's own G-N bond?

Another possibility to look for could be that maybe there are two GFCIs in series? One in the RV and another in the house. AFAIK this will not work.

Sometime extension cords have leakage as well - perhaps try another cord that is a high end / commercial grade, 20 or 30 amp rated cord. McMaster sells them and you can for instance a 10 awg version and the ends you want on them.

 

[Bigbillsd]

I have mine setup using a Magnum MS2812. I have an L14-30R mounted just outside the Inverter bay in a covered box, its in a small area that is behind a door, but open to the road below so I don't need to leave one of my bay doors open to allow cords out. I also have a quick connect mounted in that same area to hook in my 400w solar suitcase if needed. I mounted a 100' SO cord with an angled L14-30 plug on the spool it came on to the inside garage wall right next to the Genny Inlet. My Magnum manual had complete instructions including drawings. I only have 120 volts from the Inverter & Genny, but on two legs, so I turn off all double breakers in the panel except the incoming Genny breaker that feeds both sides of the panels. I am able to run both my fridge and chest freezer, as their combined load when running the compressor at the same time is <200 watts. Leaves plenty of room to run lights, TV
s, Fans and even the natural gas furnace... I have not tested the mobile AC, I will have to check its power consumption if I wanted to try it. My RV roof has 1300w of solar flat mounted to help keep my 700 AH of LiFePo4 charged, plus a 7500w diesel genny with a that 150 gallon tank if needed and that 400w suitcase mentioned earlier. We have very few blackouts in San Diego, so that is why I just added a few parts to my existing RV solar & Inverter system as emergency power.

 

[rustythorn]

Given the limited inverter output i also think that just rearranging all critical loads to one leg and leaving the other dead is probably the simplest approach.

You could also do the autotransformer idea but again, given the limited output of the inverter I'd probably skip that mess because not many 240 appliances would run on that size of inverter to begin with.

i would agree but since it is a victron and since they might still have a generator then they could hook up the inverter to the whole house 240 with an autotransformer but turn the generator on if they need an extra boost of power, depending on the victron model and the power of the generator they could increase their 3000 watts to 10000 watts

 

[Marine359]

Easiest is single phase to a 15 amp generator receptacle on the house. Just completed this install. From inlet on house, ran 12/2 romex to an outlet I installed near mains. i connect my powerstation ac charge cord to this outlet. I can then feed this circuit with a small generator, or an extension cord from my RV. Powerstation is 2Kw, and RV LFP is 2Kw. RV feeds the powerstation, which is connected to a transfer switch panel carrying only critical loads. Trying to do 240 split phase is electrically complicated and expensive. If the project is just for home backup, most people can live without 240v for a few days. It really only takes 7Kw to run a typical house for 24 hours (only critical loads).

 

[justinm001]

Easiest is single phase to a 15 amp generator receptacle on the house. Just completed this install. From inlet on house, ran 12/2 romex to an outlet I installed near mains. i connect my powerstation ac charge cord to this outlet. I can then feed this circuit with a small generator, or an extension cord from my RV. Powerstation is 2Kw, and RV LFP is 2Kw. RV feeds the powerstation, which is connected to a transfer switch panel carrying only critical loads. Trying to do 240 split phase is electrically complicated and expensive. If the project is just for home backup, most people can live without 240v for a few days. It really only takes 7Kw to run a typical house for 24 hours (only critical loads).

If just 15a I'd think running extension cords from outside through a window would be best since just emergency temporary.

 

[Marine359]

Yah agreed, if you don’t mind extension cords running all over your house. I suppose that’s tolerable for a one day outage, but running the basement furnace is another matter. I dunno, I’m lazy. New setup allows me to just go flip a couple of switches to keep our house running for a day with no extension cords. Call me old and lazy.

 

[Checkthisout]

Just put a jumper in your 120/240 cord between the two hots and run like 10 gauge extension cord and plug into the RV's exterior outlet.

Done.