Generator Wiring to Chassis Question '94 Brave

[Cupcake]

Hi, I have a question about the 110V Alternating Current wiring of a 1994 Winnebago Brave and the Generator (Onan Emerald Plus "BGE"). The generator has two circuit breaker switches on it's side, each providing a 110V line. Both lines go to a single junction box and connect to two separate 110V chassis wires. Based on the chassis wiring diagram, It seems like one line and breaker supply power to the shoreline plug receptical, which then powers (througn the shoreline plug) all AC components in the RV, including the roof air conditioning. The diagram shows the other generator breaker and line going directlhy to the roof Air Conditioner Selector Switch. But turning this breaker off or on doesn't seem to effect anything.

Does anyone know what the second generator breaker is suppose to protect or control? What should stop working if I turn if off? I'm wondering if I have a chassis wiring issue.

Thanks,

John

 

[Cupcake]

Hi. It just occurred to me that maybe the second breaker and line is just to supply extra power to the Roof Air Conditioner for the surge when it is starting. Is that it? Thanks.

 

[Gary RV_Wizard]

As you observed, the secondary generator output is used to directly feed one of the roof a/c units. It has nothing to do with start-up surge. An RV with a 30A main power panel doesn't have enough amperage available to reliably supply two a/c units simultaneously. Many coaches with this limitation have some extra features to help cope. One is an a/c selector switch, enabling the owner to choose which of the two a/c units receives power from the main 30A panel. That allows you to use the front a/c during the day and switch power to the rear a/c for overnight use. For coaches that have a larger generator (at least 40A/5000 watt capacity), another feature is the secondary generator feed, which allows you to utilize the generators extra amps to power a second a/c. In systems that have the dual a/c selector switch, this feed may be wired to power which ever a/c unit is NOT currently powered by the main panel. The only thing that secondary generator breaker affects is whichever a/c that secondary feeder is powering, usually the rear a/c. Therefore it is effective only when using both a/c units and the shore cord plugged to the generator outlet (i.e. when using the generator for power). If you look at the section of the wiring diagram that shows what is beyond the dual air selector you should be able to see how that works.

Do you have the owner manual for the coach? It should describe the use of the a/c selector switch or switches. If not, download a copy from the Winnebago site Owner Resources at https://www.winnebago.com/Files/Files/Winnebago/Resources/OperatorManuals/Operator1994/94Brave.pdf

 

[Cupcake]

As you observed, the secondary generator output is used to directly feed one of the roof a/c units. It has nothing to do with start-up surge. An RV with a 30A main power panel doesn't have enough amperage available to reliably supply two a/c units simultaneously. Many coaches with this limitation have some extra features to help cope. One is an a/c selector switch, enabling the owner to choose which of the two a/c units receives power from the main 30A panel. That allows you to use the front a/c during the day and switch power to the rear a/c for overnight use. For coaches that have a larger generator (at least 40A/5000 watt capacity), another feature is the secondary generator feed, which allows you to utilize the generators extra amps to power a second a/c. In systems that have the dual a/c selector switch, this feed may be wired to power which ever a/c unit is NOT currently powered by the main panel. The only thing that secondary generator breaker affects is whichever a/c that secondary feeder is powering, usually the rear a/c. Therefore it is effective only when using both a/c units and the shore cord plugged to the generator outlet (i.e. when using the generator for power). If you look at the section of the wiring diagram that shows what is beyond the dual air selector you should be able to see how that works.

Do you have the owner manual for the coach? It should describe the use of the a/c selector switch or switches. If not, download a copy from the Winnebago site Owner Resources at https://www.winnebago.com/Files/Files/Winnebago/Resources/OperatorManuals/Operator1994/94Brave.pdf

Thank you for that very complete response. The generator is 40amp/5000 watt. So if I understand correctly I should be able to run both roof air conditions at the same time when powered by the generator. When powered by the shore line to external service I can only run one at a time. (I do have a manual but didn’t see anything addressed but the selector switch; I’ll look again and check the link). Thanks again.

 

[Tulecreeper]

Thank you for that very complete response. The generator is 40amp/5000 watt. So if I understand correctly I should be able to run both roof air conditions at the same time when powered by the generator. When powered by the shore line to external service I can only run one at a time. (I do have a manual but didn’t see anything addressed but the selector switch; I’ll look again and check the link). Thanks again.

That is correct, if you have a 30A supply it can only power one A/C unit at a time. A 5000w generator should be able to run them both simultaneously, but you will still need to monitor the usage of your other high-amp items, like a microwave or blow dryer.

 

[Cupcake]

That is correct, if you have a 30A supply it can only power one A/C unit at a time. A 5000w generator should be able to run them both simultaneously, but you will still need to monitor the usage of your other high-amp items, like a microwave or blow dryer.

Thanks. Theoretically, what do you think happens if I plug in the shore line to an external supply, select and run the front air conditioner, and at the same time try to run the rear Air conditioner with the generator?

 

[Tulecreeper]

Thanks. Theoretically, what do you think happens if I plug in the shore line to an external supply, select and run the front air conditioner, and at the same time try to run the rear Air conditioner with the generator?

I think that's how it is supposed to work.

I'd have to see your control panel, but I believe if you have a dual A/C selector switch you can set it to have your shore power provide power to (for example) the entire coach and A/C #1. Then, if you power up the generator the only thing it will provide power for is A/C #2. In that scenario, you still need to watch your usage of anything else that is on the same circuit as your shore power and A/C #1 because you still only have 30 amps to work with and A/C #1 is using most of them. Which means you still can't run a microwave and/or blow dryer while A/C #1 is running.

I think in your case, the selector switch (depending on which direction to have it flipped) will allow you to run either the entire coach and A/C #1...or, the entire coach and A/C #2 from shore power and it automatically switches the generator to the other A/C unit. If that is so, then in my opinion they installed a generator that is way too big for simply supplying power to a single A/C unit.

Gary...??

 

[Gary RV_Wizard]

Thanks. Theoretically, what do you think happens if I plug in the shore line to an external supply, select and run the front air conditioner, and at the same time try to run the rear Air conditioner with the generator?

I don't know if your set-up will do that. Would have to examine the full wiring diagram to determine that. The typical use would be to run both on generator, but it's theoretically possible to wire so that mixed sources will work. The Winnie manual is of no help on this.

 

[Cupcake]

Thank you.

 

[johnhicks]

I have a similar setup with an Onan 6500 gen.

On shore power, the switch is front or rear. On gen, the switch is to be set to front, getting power via the transfer switch. The rear a/c gets power directly from the gen, no switch or transfer switch involved, just a breaker on the gen. The gen has two outputs, 30a for house and 20a for the rear a/c. That's how you can run both a/c units on gen.

If the transfer switch defaults to shore power, it might be possible to backfeed or release the magic smoke by having the switch set to rear with the gen running and shore power comes on.

 

[jubileee]

On a couple of 30 amp nineties units we’ve had, I just wired 120 ac male/female plug in the generator box into the line going to the rear ac with male plug towards the ac.
Then to run rear air at campground, just unplug line and plug in good extension cord to the 20 amp receptacle.at post.
To run both off generator, just plug line back together.

 

[John Canfield]

The male plug was hot?

 

[Cupcake]

On a couple of 30 amp nineties units we’ve had, I just wired 120 ac male/female plug in the generator box into the line going to the rear ac with male plug towards the ac.
Then to run rear air at campground, just unplug line and plug in good extension cord to the 20 amp receptacle.at post.
To run both off generator, just plug line back together.

Neat. So you essential created a second shoreline, for 20 Amp service, dedicated to the rear AC.

 

[Tulecreeper]

The male plug was hot?

That was also my question.

 

[Ray-IN]

You can look up and download all the wiring schematics for your particular Winnebago MH from: Wiring Diagrams