Microwave kicking out inverter breaker on shore power

[Enerloss]

We have a 2008 Berk that we picked up last fall and it came with a Magnum 1200 watt inverter. The microwave is an Amana that is rated at 1500 watts. Why FR would only put a 1200 watt inverter in with a microwave that draws 1500 watts escapes logic IMHO but that's another issue. So I realize using the microwave without shore/genie power is a no-no.
When we're on shore or generator power and try to use the microwave on full power it kicks the breaker out at the inverter. Not right away, but after 20-30 seconds. The inverter is not turned on.
I'm a backyard mechanic and only have a basic knowledge of electricity but I would think I should be able to use the microwave on shore or genie power without kicking out the inverter? I thought at first the issue was the microwave but why would the inverter even be in the circuit while on shore/genie power? Do I have 3 way switch problems?
FYI. The inverter is new last spring c/w with 4 new Trojan house batteries.
Love to hear your thoughts because the Boss is not a happy camper.

[N6ZCM]

Originally Posted by Enerloss

We have a 2008 Berk that we picked up last fall and it came with a Magnum 1200 watt inverter. The microwave is an Amana that is rated at 1500 watts. Why FR would only put a 1200 watt inverter in with a microwave that draws 1500 watts escapes logic IMHO but that's another issue. So I realize using the microwave without shore/genie power is a no-no.
When we're on shore or generator power and try to use the microwave on full power it kicks the breaker out at the inverter. Not right away, but after 20-30 seconds. The inverter is not turned on.
I'm a backyard mechanic and only have a basic knowledge of electricity but I would think I should be able to use the microwave on shore or genie power without kicking out the inverter? I thought at first the issue was the microwave but why would the inverter even be in the circuit while on shore/genie power? Do I have 3 way switch problems?
FYI. The inverter is new last spring c/w with 4 new Trojan house batteries.
Love to hear your thoughts because the Boss is not a happy camper.

How does a breaker trip at the inverter, when the inverter is OFF? Sure it is OFF?

Unless it has a built in transfer switch... regardless of running on Generator or shore power the inverter is still not large enough to run the microwave!

There must be a transfer switch to take the Inverter off line and switch shore power to the RV

[Enerloss]

When I said it was off I meant we had not turned the inverter on at the control panel inside the unit (as if we were at a stop and using batteries for the house). There is a transfer switch which I called the 3 way switch, my mistake.
I would think so too that the inverter should be out of the circuit, at least for internal house power, when we're on shore/genie power. The inverter is also the battery charger so in my mind it should be charging batteries but not powering equipment inside the house. Everything else works fine.

[N6ZCM]

Originally Posted by Enerloss

When I said it was off I meant we had not turned the inverter on at the control panel inside the unit (as if we were at a stop and using batteries for the house). There is a transfer switch which I called the 3 way switch, my mistake.
I would think so too that the inverter should be out of the circuit, at least for internal house power, when we're on shore/genie power. The inverter is also the battery charger so in my mind it should be charging batteries but not powering equipment inside the house. Everything else works fine.

Sounds like you need to turn the switch before operating any AC product inside, that being said... maybe some things are on the inverter some not. i.e. Fridge, microwave, T.V. but A/C is not.

Maybe post some pics of your setup would help.

If the inverter has a built in transfer switch, possible it is set to be always ON, does not transfer shore power to the appliances, where AUTO would select Shore power when detects voltage, and back to Inverter when there is no AC detected.

[dreamin533]

Enerloss, which model of Berkshire do you have? I own a 2008 Berkshire 360QS and live in Kingston, just down the road from you. We had a similar problem with the magnum inverter except ours had an issue with the internal switch. If we turned it off inside the coach we couldn't tell whether it was on or off and in the process drained our batteries down to around 8.5 volts. The batteries were okay but the inverter was toast ( don't trust magnum as a result). I removed the inverter and just put in a PD charger. I also had to have the auto transfer switch replaced under warranty. If you have any questions email me with a phone number and we can discuss issues. Where did you buy your Berkshire?

[turbocc]

If the micro is capable of being powered by the inverter, then it has to have a transfer switch to take it off the inverter when on shore/ genie power. Otherwise you are using the inverter pass-thru function which in your case is only 1200 watts. 1500 watts will not pass-thru a 1200 watt inverter. Will trip the inverter breaker. These facts aside, major problem with 1500 watt micro and a 1200 watt inverter. Square peg round hole.

[zuckerburg]

Originally Posted by Enerloss

We have a 2008 Berk that we picked up last fall and it came with a Magnum 1200 watt inverter. The microwave is an Amana that is rated at 1500 watts. Why FR would only put a 1200 watt inverter in with a microwave that draws 1500 watts escapes logic IMHO but that's another issue. So I realize using the microwave without shore/genie power is a no-no.

When we're on shore or generator power and try to use the microwave on full power it kicks the breaker out at the inverter. Not right away, but after 20-30 seconds. The inverter is not turned on.

I'm a backyard mechanic and only have a basic knowledge of electricity but I would think I should be able to use the microwave on shore or genie power without kicking out the inverter? I thought at first the issue was the microwave but why would the inverter even be in the circuit while on shore/genie power? Do I have 3 way switch problems?

FYI. The inverter is new last spring c/w with 4 new Trojan house batteries.

Love to hear your thoughts because the Boss is not a happy camper.

I have a 2011 RB Berkshire. Your micro should not be wired to the inverter. Mine isn’t. As to how or why this is connected on yours is I can guess. Either the previous owner did some rewiring or they mucked it up at the factory. Either way you will need to fix it or just don’t use the microwave when on inverter. The nice thing is your clock will work but don’t use the microwave.

[turbocc]

Bottom line, a 1500 w micro should never be run through a 1200 w inverter. Period.

[zuckerburg]

Originally Posted by turbocc

Bottom line, a 1500 w micro should never be run through a 1200 w inverter. Period.

I agree. What I was saying was no other Berkshire I have ever seen has the microwave wired through the inverter.

[Oscarvan]

The way the I/C is wired on MY unit is pretty tricky. It took me a while to get my head around it, but I finally figured it out. There is an in depth description on my blog:

https://dragonship.blog/modification...breaker-panel/

Please read it carefully as it clarifies many of the misconceptions and inaccuracies voiced above.

So yes, my microwave runs through the inverter.... even though it has it's own breaker...... the right side of my panel is a de facto sub panel, and EVERYTHING there comes through the 30A inverter breaker first. I can also power my microwave (NOT THE SAME THING) with my inverter when there is no shore power.

Now, all that said I believe that the older Berks had less that was capable of being powered by, or with shore power available, running THROUGH (as in passing through unaffected) the inverter. I believe that the Microwave was NOT in the older units. (Again, it IS in my 2017) I don't know whether the sub circuit breakers in the older units are in the main panel or on the I/C itself.

So, to find the true answer to this problem you have to take the cover off the 120V breaker panel, and you have to figure out what is or is not wired through (and capable of being powered by, if no 120V) the inverter.

So to the original post.... the wattage of the microwave versus that of the inverter only matters when inverting. When NOT inverting the circuits that can normally be powered by the inverter still pass through the inverter, but unaffected. NOT subject to the wattage rating of the inverter, only subject to the AC breakers in their circuit.

And yes, there appears to be a mismatch there. Now, if the microwave is NOT capable of being powered by and thus does not run through the inverter (remember mine DOES and CAN be powered by the 2000W inverter that I have) it should not be popping the inverter breaker. This leads me to believe that it is wired like the newer units. In this case it is possible that someone replaced the microwave with a heavier unit (and knew not to run it full power), or the inverter/charger with a lighter unit.....OR someone changed the wiring around to the newer schematic, but did not match the units in question.

It is also possible that what the OP thinks is the inverter breaker is in fact a sub breaker for one of the circuits fed through the I/C which COULD be popping due to a bad breaker.

There are a lot of possibilities here. Again.....tracing the schematic and figuring out what runs where is the ONLY way to know what's going on.

[Enerloss]

I was just saying to my wife on the weekend that I am going to have to trace the wiring back to the panel and figure out a way to re-wire it. Thank you Oscarvan; your post makes my life so much easier.

[Oscarvan]

You're welcome. If you end up scratching your head post here, pictures help. I'll try to help you figure it out.

[Enerloss]

Success!!
Once I poked around inside the breaker panel your info helped me a lot to understand what was happening. Moved the microwave power to the laundry/dryer breaker as we do not have a washer. Washer breaker is 20 amp as is the microwave breaker.
Once again, thank you.
Glenn

[turbocc]

I must take exception with "pass-thru inverter unaffected". Anything that passes thru the inverter will also need to be powered by the inverter in inverter mode. The only way it would not would be some type of relay to remove the micro from pass thru when inverter is turned to invert. Sounds too complicated for an RV manufacturer to do that, but......

[Oscarvan]

Originally Posted by Enerloss

Success!!
Once I poked around inside the breaker panel your info helped me a lot to understand what was happening. Moved the microwave power to the laundry/dryer breaker as we do not have a washer. Washer breaker is 20 amp as is the microwave breaker.
Once again, thank you.
Glenn

[Oscarvan]

Originally Posted by turbocc

I must take exception with "pass-thru inverter unaffected". Anything that passes thru the inverter will also need to be powered by the inverter in inverter mode. The only way it would not would be some type of relay to remove the micro from pass thru when inverter is turned to invert. Sounds too complicated for an RV manufacturer to do that, but......

Not sure I understand your point. Yes, when there is no AC these circuits are powered by the inverter. When there's AC available, generator or shore no matter, the inverter does not do anything to the circuits involved and passes the current through. That would be unaffected.