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Subpanel is 99% 120V except by Dryer that is 240V. Is it still okay to connect the Inverter AC-OUT 120V into both L1/L2 ?

No Hazzard.
It just won't work on 120v.

I think it will work, just no heat.
Motor and controls get 120V and operate as before.

If this is 120V backup for a house that normally gets 120/240V, would be a reasonable thing to do.

If you want it to work on 120V, could rewire dryer for 120V. Either keep existing 30A 120/240V plug or change to 120V plug.

For maximum WAF (wife acceptance factor) with 120V backup, add a switch or relay to the dryer so heating element switches between 120V and 240V.

Usually it's a 3 wire romex. Black, red,white, and bare.
Black and red are circuits on L1 and L2, white wire is the neutral for both. (Shared neutral)
Since you will be combining L1 and L2, a multi-wire branch circuit neutral would have to carry twice the current.

If there had been a MWBC, could be fixed by connecting red and black both to the same 20A breaker. Then white isn't asked to carry more than 20A, no problem.
 
I think it will work, just no heat.
Motor and controls get 120V and operate as before.

If this is 120V backup for a house that normally gets 120/240V, would be a reasonable thing to do.

If you want it to work on 120V, could rewire dryer for 120V. Either keep existing 30A 120/240V plug or change to 120V plug.

For maximum WAF (wife acceptance factor) with 120V backup, add a switch or relay to the dryer so heating element switches between 120V and 240V.
The dryer outlet is not even being used.
They have a gas dryer.
If there had been a MWBC, could be fixed by connecting red and black both to the same 20A breaker. Then white isn't asked to carry more than 20A, no problem.
Correct
 
Thank you everyone... you guys are experts.
So, for now have 2 homeworkes:
  1. Learn my usage on the sub-panel so I can know exactly what Im using and have a good idea what would be best size of my solar system
  2. Learn more about permits that I will need :-( that will be probably the bore part and hope I can find a company that will work with me to get everything 100% legal
Thank one more time everyone
 
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Perfect! Get yourself one of these:


61amKmEgcDL._AC_SL1500_.jpg


:devilish:
 
@usphisics On your emporia go to menu/notifications/ add alert. There add an alert for mains consumption of slightly lower than the rated surge of the inverter your looking at for 3 sec. (Or rated constant for 30sec)
It will send you an alert if that sub panel exceeds the surge (constant) watts of the inverter
 
@usphisics On your emporia go to menu/notifications/ add alert. There add an alert for mains consumption of slightly lower than the rated surge of the inverter your looking at for 3 sec. (Or rated constant for 30sec)
It will send you an alert if that sub panel exceeds the surge (constant) watts of the inverter
Thank you…. I just created one alert. But that is nice to be able to see 18 breakers/appliances usage.
Most part of the time the load is less than 500wh but once wife and kids get home they start to turn on stuffs on and then it goes closer to 1kWh.
So far the biggest load are microwave, kettle, air fryer and suffs like that. That is when I can have peaks over 2kWh.
So far per day it is between 10kWh and 12kWh. Weekend probably will be more, lets see….
But it is really nice to be able to see where and understand my loads, so it will for sure change my mind set about the size of my future system.
 
I didn't see this mentioned in the thread, but, If you are connecting one leg to both sides of the bus, doesn't that mean you are loading up one circuit of your 240V 2 phase inverter? If this does not apply, let me know and I will delete this comment.
It's a single phase 120v inverter.
 
I don't see any multi-wire branch circuits. So, you are good to go.
@timselectric sorry to bother you again but I was reading about the MWBC and I think I got the basic concept about it and as you said before it looks like that I don't have it between my sub panel and the house BUT going back and looking between the main-panel and the sub-panel, would not that be the case? I mean that is a MWBC, right? L1 and L2 sharing the Neutral wire..... So having that in mind (if Im right) I keep thinking what would be the current flow if I set up the system as I was thinking....
  • Turn off the break that connects the main and sub panels, so L1/L2 between them would not have current but Neutral would stay connected/shared between them all the time, right ?
  • Now on sub-panel I have a source of power ON. Like my solar system. And as the original ideal was, I connect my 120V wire into both L1 and L2 so I can have current in both side of my sub-panel, it would be 120V single phase as we already discuss about it (again not split phase).
  • Now I go home and turn on something, like TV or light, whatever. The current flow would comes from the source to power what ever it needs and comes back to the source via neutral wire, right ?
So the last step is where I have questions...... Will the current travels back to the source JUST USING neutral wire/bus bar from the sub-panel OR it would somehow travel to the main-panel for some reason. Sorry, again super newbie/ignorant person here :cry:
On my heat I have that the current would do the shortest path back to the source, so it would not have current flowing back to the main-panel at all even it and sub-panel still having a shared neutral BUT again, just to be safe I prefer to ask/bother you, sorry... LOL
 
@timselectric sorry to bother you again but I was reading about the MWBC and I think I got the basic concept about it and as you said before it looks like that I don't have it between my sub panel and the house BUT going back and looking between the main-panel and the sub-panel, would not that be the case? I mean that is a MWBC, right? L1 and L2 sharing the Neutral wire..... So having that in mind (if Im right) I keep thinking what would be the current flow if I set up the system as I was thinking....
  • Turn off the break that connects the main and sub panels, so L1/L2 between them would not have current but Neutral would stay connected/shared between them all the time, right ?
  • Now on sub-panel I have a source of power ON. Like my solar system. And as the original ideal was, I connect my 120V wire into both L1 and L2 so I can have current in both side of my sub-panel, it would be 120V single phase as we already discuss about it (again not split phase).
  • Now I go home and turn on something, like TV or light, whatever. The current flow would comes from the source to power what ever it needs and comes back to the source via neutral wire, right ?
So the last step is where I have questions...... Will the current travels back to the source JUST USING neutral wire/bus bar from the sub-panel OR it would somehow travel to the main-panel for some reason. Sorry, again super newbie/ignorant person here :cry:
On my heat I have that the current would do the shortest path back to the source, so it would not have current flowing back to the main-panel at all even it and sub-panel still having a shared neutral BUT again, just to be safe I prefer to ask/bother you, sorry... LOL
It won't travel to the main panel.
Shortest path is correct.

And panel feeders are not in the category of a multi-wire branch circuit. Just an FYI.
 
It won't travel to the main panel.
Shortest path is correct.

And panel feeders are not in the category of a multi-wire branch circuit. Just an FYI.
Thank you sir...... this post started as a question about a 240V dryer outlet and became a really good and nice class about panels....
Thank you again....
 
And panel feeders are not in the category of a multi-wire branch circuit. Just an FYI.

But aren't they subject to the same issue, loss of neutral applies incorrect voltage to 120V load?

(Also, if you connected a really large 120V generator feeding L1 + L2 then N could be overloaded, but any reasonable generator of such size would be split phase, so not going to happen.)
 
But aren't they subject to the same issue, loss of neutral applies incorrect voltage to 120V load?
Loss of any split-phase neutral is an issue. (For 120v loads)
But it's not a code violation.
(Also, if you connected a really large 120V generator feeding L1 + L2 then N could be overloaded, but any reasonable generator of such size would be split phase, so not going to happen.)
Correct on both statements.
 
Hi @Hank Waconda , not if I understood what you said. But here is what I have today in my main panel.
View attachment 147436
View attachment 147437
It is a 240V split phase for the generator breaker with the interlock. It is to be use by a Wen GN625i.
https://generatorbible.com/generators/wen/gn625i/

So it is a invert generator and I hook up it using its 240V 30A (L14-30R) receptacle into my main panel today and it is able to run everything, except the furnace, in my house. Even the AC heat pump with a easy started it can run.
But again, the idea is to isolate the sub-panel L1/L2 wires but as you guys said the neutral will be shared, is that okay or something else to take into consideration ?

Here is my sub-panel.
View attachment 147441
And you can see it doesnt have a Top Main breaker. The idea is (if possible) move the 2 top right breakers (kitchen GFCI outlets) to the botton and add a 240v breaker for the Solar system 120v AC output but connecting both L1/L2 as that was the idea. And of course the Solar system breaker and the Top Main one MUST have a Interlock.



Thank you....
In the subpanel, only the 2 20A breakers in the bottom left could have a shared neutral. The reason is that none of the AFCI breakers above are for shared neutrals (they take 2 slots and cost a fortune, asked me why I know ;-).

To find out if those 2 breakers share a neutral, follow the wires from them to wherever they enter the panel. If they come from the same Romex cable, you're out of luck: they have s shared neutral. If not, you should be fine in this regard.
 
If they come from the same Romex cable, you're out of luck: they have s shared neutral. If not, you should be fine in this regard.

Simple solution in that case - put both hots in one breaker.
The two circuits are then limited to 20A total, but you can drive the panel single phase and not overload neutral.
 
Simple solution in that case - put both hots in one breaker.
The two circuits are then limited to 20A total, but you can drive the panel single phase and not overload neutral.
Clever! After that, adding an AFCI/GFCI combination outlet to the first outlet, if any, inside the house for each circuit would probably be enough protection.
 
AFCI/GFCI outlet could protect itself, but likely not work for daisy chained outlets because it would see only one hot leg but combined neutral currents. You can use a single pole AFCI/GFCI breaker.

Was the issue related to AFCI/GFCI? I assumed it was feeding single phase to a split-phase panel.
 
First of all, I'm super new on this solar/inverter world. So, please, easy....
Here is my scenario that Im pretty sure that a lot of people may have something similar.
  • Main panel receives 240V split phase from grip.
  • Everything in the main panel has a 2 pole breaker (240v split phase)
    • Generator 30amps breaker (it has an Interlock)
    • AC heat pump breaker
    • Furnace heater breaker
    • Sub-panel breaker
  • At the sub-panel 99% of all breakers are 120V (15amp or 20amp) EXCEPT by the Dryer that is 240V that I DONT USE AT ALL as I have a gas dryer, but the breaker/outlet everything is there just in case I (my wife) need it.
When I started to study about this solar/inverter world I came with the idea to not touch in the main panel (at least for now) and just connect the sub-panel into the solar system. So still using the grid/generator for the AC/Furnace and using another Interlock in the sub-panel to be able to totally disconnect it from the main panel and at the same time safely allowed connect it into the solar system. Or even in case of a main failure in the solar system be able go back and reconnect the sub-panel into main panel 100%.
So far so good until I start to think which would be the a good inverter to my design. First thing that came to my mind is that I would need to have a 240v split phase inverter. In my mind it is simple. 240V split phase comes from the main panel, so in order to replace it I also need a 240v split phase. So I started to research by reliable 240V inverters, like the ones from Schneider as they look to be bullet proof beasts. But then I red in this forum someone talking about have 240v split phase VS really have 240v split phase loads and as I said before, on my sub-panel 99% of the breakers/loads are single 120V phase EXECEPT by a 2 pole breaker for the dryer THAT I DONT USE AT ALL (at least now).
So we go back to the title of this post. It looks like that I could use a nice 120V single phase interver to connect into my sub-panel and have both L1 and L2 legs connected. So this way I will have 120v single phase (not 240v split phase) into both legs.
  • IS IT RIGHT ? 120v connect into both L1/L2 legs of my subpanel
  • If so how I would do with that dryer breaker ? Is it okay to leave it there ?
  • If I lease it there what happens if in the future someone goes and connect a dryer into it while the solar system is the one that is providing power to the sub-panel ? Is it safe or even legal ?
Sorry my long post but as I said... Im totally newbie and just trying to learn as much it is possible.....

Thank you everyone......
L2 must be 180 degrees off from L1. What you have suggested will not work
 
(some) dryers can be rewired to run off 120V. Apparently newer GE use 240V for controls and motor, but the ones I have didn't. That could let you do all 120V.

If you do connect L1 an L2 in parallel, and branch circuits with shared neutral and separate 20A breakers on red & black wires could but 40A through neutral, no bueno!

Examine your circuits to see if any 3 + ground cables go to two separate breakers. Or a 2-pole could have been used this way. Understand what is connected to any 3 + ground cables.
 

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