Question on inverter/charger AC backfeed

[JaimeTheLimey]

Hi all. New member here about to pickup a Grand Design this weekend and I'm already planning out upgrades to make the rig 100% usable off grid.
I'm versed in electrical but the whole inverter/charger thing is new to me and I have concerns with the split phase nature of them.
Can someone correct me if I'm wrong, but if you run one leg of the 50A service to the inverter and the second leg directly to the panel, when the inverter is running wouldn't you be backfeeding the second leg.
Seems that unless you kick off the breaker to that leg your shore power connection will be hot. My old Lance 5th wheel only has a male connection so that would be a major concern.
Any input your have is appreciated. Thanks.

[Veebyes]

MrWizard wrote:
No need for open leg
Use a 50 > 30 > 20 adapter's
Plug into the inverter If the inverter is the hard wired type
Wire with short cord to a 30a or 50a adapter
Using an outlet and plugging in shore cord is foolproof
You can NEVER be cross connected for a dangerous n situation

Another way to do it. There are always multiple ways around a problem. No matter what though turn the circuit breakers off to the converter, water heater & fridge. Battery bank killers.

[MrWizard]

No need for open leg
Use a 50 > 30 > 20 adapter's
Plug into the inverter If the inverter is the hard wired type
Wire with short cord to a 30a or 50a adapter
Using an outlet and plugging in shore cord is foolproof
You can NEVER be cross connected for a dangerous n situation

[Veebyes]

I am not a tech but have had some inverter experience on the water & on land.

Backfeeding is not good. It involves a loud bang & smoke as the inverter is destroyed.

These days I like doing things manually. I have a 1500w pure sine wave inverter going to the automatic transfer switch & a converter/charger.

Part of the drill for dry camping is to turn the breaker powering the converter/charger off, along with the water heater, microwave & fridge breakers. For shore power the inverter is turned off, i.e. not in the automatic mode.

[librty02]

larry cad wrote:

theoldwizard1 wrote:

pianotuna wrote:
Hi Larry,

My inverter powers a 30 amp female plug. I plug the shore power cord into that inverter powered outlet.

Best non-automatic transfer switch you can have ! Simple and not too expensive.

Had to think about it for a minute, but now I understand exactly that.

This is fairly common just plug the shore power cord into an inverter. You just have to watch how many watts you pull at a time not to overload the inverter...and drain your batteries quickly...the biggest thing is turning off the breaker for the converter in the rig. With the breaker on you would be using your batteries to charge your batteries and that will drain them very quickly...it would be a never ending cycle ha!

[2oldman]

pianotuna wrote:
Are you saying you wish to run the RV as an uninterruptible power supply?

Just the DTV. My MW clock will stay on time if I make the manual switch fast enough.

My old Prosine 2.0 had a fast enough switch to keep the older DTV SD receiver on, but the HD ones are really sensitive.

[pianotuna]

2oldman,

Are you saying you wish to run the RV as an uninterruptible power supply?

In fact, because I do have an inverter/charger that does load support, that is how my unit could be run.

It also means that if running on the generator, and fuel is needed I can continue powering the RV.

I use a patch panel approach for those times when shore power "hates" the Magnum (gfci some don't like Magnum).

My apologies as this is off the topic which is back feeding--which any thinking person would agree is a lousy and dangerous practice.

[2oldman]

theoldwizard1 wrote:
Best non-automatic transfer switch you can have

Unless you have sensitive equipment like a DTV receiver which will shut down and take 7 minutes to reboot in the middle of recording your favorite show.

I use a 3pdt manual knife switch, but, my receiver is hard-wired to my inverter which is never off.

[larry_cad]

theoldwizard1 wrote:

pianotuna wrote:
Hi Larry,

My inverter powers a 30 amp female plug. I plug the shore power cord into that inverter powered outlet.

Best non-automatic transfer switch you can have ! Simple and not too expensive.

Had to think about it for a minute, but now I understand exactly that.

[theoldwizard1]

pianotuna wrote:
Hi Larry,

My inverter powers a 30 amp female plug. I plug the shore power cord into that inverter powered outlet.

Best non-automatic transfer switch you can have ! Simple and not too expensive.

[larry_cad]

pianotuna wrote:
Hi Larry,

My inverter powers a 30 amp female plug. I plug the shore power cord into that inverter powered outlet.

larry cad wrote:

pianotuna wrote:
I simply plug the shore power cord into an outlet powered by the inverter.

HUH??

:h

Interesting concept. I've never seen that done.

[pianotuna]

Hi,

Victron, Outback, and Magnum all make units that have transfer switches.

JaimeTheLimey wrote:
The only make I know of who has a full 50A passthrough is Go Power but I've read mixed reviews on them.

[pianotuna]

Hi Larry,

My inverter powers a 30 amp female plug. I plug the shore power cord into that inverter powered outlet.

larry cad wrote:

pianotuna wrote:
I simply plug the shore power cord into an outlet powered by the inverter.

HUH??

:h

[time2roll]

JaimeTheLimey wrote:
I should clarify that my plan is to have the inverter wired into the panel so I can run anything on shore power or battery bank/solar.
I suppose you should just switch off the second leg breaker but it sort of squashes the whole automatic switching thing. The only make I know of who has a full 50A passthrough is Go Power but I've read mixed reviews on them.

Get a stand alone inverter and a separate 50 amp transfer switch.

I like GoPower but I have read posts of trouble with the all in one unit. My 2000w sine wave (inverter only) has been great.

[theoldwizard1]

JaimeTheLimey wrote:
Can someone correct me if I'm wrong, but if you run one leg of the 50A service to the inverter and the second leg directly to the panel, when the inverter is running wouldn't you be backfeeding the second leg.

In theory, no ... BUT SHARING NEUTRAL BETWEEN 2 POWER SOURCES IS SOMETHING I WOULD NOT WANT TO DO !

Also, if you have any 240 loads, you are going to get "wild and crazy" voltages and frequencies !


The good news is that most modern inverter chargers include an automatic transfer switch and they will shutdown the inverter as soon as they see "shore power". Unless you do some unusual wiring, your scenario can not happen.

BFL13 wrote:
Inverter/chargers have installation manuals. It is common to have an inverter/charger with a 50a RV. Just do what the manual says and you will be fine.

What he said !