i am trying to get a better understanding of this...

if you disconnect your grid service permanently and hook a 120v inverter 2500 watt up to your panel ,you will have to use a single pole breaker and only one buss will be active. There is also an important issue
with the neutral bond to ground thing.... you would have to disconnect it ...that part is confusing

120v inverters are more common and cheaper and I dont need any 240v.
Now if you have multi branch circuits you will lose some outlets . But you could pull out the 240v circuits and use the free slots to move the mbc 2nd wire to the active buss with its own breaker though it wont have a neutral....
and as long as you dont exceed the amp rating for the 2 wires together it should be okay..
does this sound about right??

 

The problem with a MWBC is that it only works with 240vac. If you convert your panel to 120vac only and move the second circuit so that they are both on the same leg..... you can overload the neutral. If you had a 20A MWBC and you put both breakers on the same leg.... you could potentially draw 40A thru the neutral.

 

Where are you proposing to obtain your electricity if you disconnect from the grid? Your post didn't address that.

 

obviously from batteries....
PJ I see the problem..
btw what is the issue with neutral bonded to ground ???

 

I believe with an inverter in use like you are proposing..... you will need the neutral and ground to be bonded to supply ground to the receptacle.

I'd have to look this up to be sure unless someone else knows the answer.

 

But where will you obtain the electricity to charge the batteries? They will only last a few hours at most.

 

Nothing is "obvious". That is why we ask questions.

 

solar...............................

 

If you take the red and black wires of a multiwire branch circuit entering the panel and connect both of them to a short length (pigtail) of wire and connect the pigtail to one 15 amp (20 amp for 12 gauge) breaker then you won't overload the neutral.

The above is not technically correct but it is safe.

Now if you withdrew the MWBC cable from the panel and ran it into a 4x4 junction box and ran a 2 conductor cable from the junction box to the panel, then you could make a legally correct hookup. Connect the black wire of the MWBC to the (2 wire) feed black and a pigtail and connect the red wire to an ordinary switch mounted in the junction box. Now you have unswitched hot and switched hot and shared neutral in the former MWBC cable and all on the same non-MWBC 120 volt branch circuit and that is legal. (Some limitations apply such as pertaining to bathrooms or kitchens.)

Then at some later date you decide you don't want the switch any more so you open up the junction box, unhook the two wires from the switch, and connect the two wires to each other.

 

Doing the above would add the two loads together and could cause the breaker to trip from overload.

 

The OP has two off the wall posts here about his proposed grid-tied inverter that he has not elaborated on one bit.

To the OP... combine your two thread for the sake of clarity and explain fully what your intentions are. They are not clear from both of the threads... personally, I suggest hiring an electrician to solve your backup power needs.

 

What exactly does this existing service currently serve? Is this a residential service to a home? 2500 watts will not be much power, maybe two 120 volt circuits at maximum output.

 

A cabin doesnt need 200 amps. Not everybody is a watt hog.
I will figure out the rest myself.