[Bill]

I’d flip the breaker on the campground’s pedestal off before I did that. That should isolate you from the shore power. Unplug if you wish.

Why are you doing this? Do you remain at the campground for a long period of time?

[Harry]

That should be fine. The way your transfer switch is set up; generator should take priority, then shore power. What I WOULD do is turn off all the a/c units and anything else you have drawing a load before turning on the generator as to make sure you dont damage the transfer switch.

We were at Disney this last May and had 3 airs running along with the dryer, lights, TVs , etc. and tripped the breaker at the pole when my wife decided to plug in her straightener while blow drying her hair. I had to unload everthing and turn the generator on so we could continue using all the power needed. Rather than having to explain power and consumption to her knowing it would only end with her telling me, “Thats why I have a bus, so I can do all this,” I just ran the generator until we were ready to go then switched back to shore power.

Long story short, I dont see a problem with running the gen while plugged in, just unload everything before you switch back and fourth.

[Per]

Most transfer switches automatically are biased towards the best power source with inverter power being the default. As soon as shore power is present the transfer switch sends power into the coach. If the generator is run, even if you are still connected to shore power the transfer switch will automatically send generator power into the coach, and disconnect shore power.

The information about shutting down loads before starting the generator or connecting to shore power is not only good advice, it should be the practice. While it is unlikely one failure to remove loads from the system will damage anything, continued failure to remove loads is ultimately going to daamge the relay contacts and eventually require repair or replacement of parts or the entire transfer switch.

Some of our coaches can automatically start the generator if shore power is disconnected such as a tripped breaker or power failure, meaning when the generator starts all the devices that were on when power was lost will still be on and the transfer switch is going to switch under load. But those are isolated incidents and should be avoided.

[Bill]

Good advise, unload the A/C’s before switching either way.

[Archived]

It is important to understand that under no circumstances should two sources of power be supplied to the coach at the same time. A proper transfer switch whether it is manual and requires the turning of a knob to select the power source, or automatic and switches when it senses power is required.

The best assurance there will never accidently be two sources of power applied to the coach at the same time is to shut one off before turning the other one on.

In the context of this discussion the transfer switch is not only selecting the best source of power, it is safely disconnecting one power supply before allowing the other to come on line.

[Archived]

Just to clarify Jon,

If I’m using 30AMP service and want to do laundry while running an A/C, or if I’m on 50AMP service and want to run all four A/Cs plus do laundry, if I turn the generator on, I should first shut down the 30AMP or 50AMP 110V service coming in from short power, despite my transfer switch automatically switching my shore power to generator power?

I guess this doesn’t apply running the generator when running down the road and your alternator is charging your batteries/running some of the devices in the bus while driving?

[Gerard]

Tim,

The way your transfer switch is intended to work is to sense the presence of power and switch to allow that power into the coach, with generator being a higher priority than shore power. There is a time delay between when power is applied to the transfer switch, before the actual switching occurs.

So if you are on shore power and want to use generator power you don’t have to do anything except start the generator. At least that is how things are supposed to work. But we all know that stuff breaks. In 27 years I have never had an issue with my manual switch or my automatic transfer switches so while I have a lot of confidence they will all do their job as intended, I want to do what is often called soft starts.

If I am on one power source (shore power for example) and want to switch to generator power I will shut down my loads. That includes the A/Cs, and anything else drawing a lot of power when I want to make the switch. Then I will shut off the shore power circuit breaker at the pole and start the generator. I have never done that except when shore power has failed or tripped the breaker so I can’t remember shutting it off because it has already been off. If I have to have 30 amp power, I just run my generator. We are past the point where we want to “rough” it.

A soft start where you are not switching under load is a good practice for everything. Using circuit breakers as switches to turn devices on and off is bad because circuit breakers are not designed to be switches and their life is shortened. So unloading the circuits before turning on breakers or changing sources is just a good practice although there are going to be instances where we cannot always do that.

The problem is if a coach should somehow get two sources of power into the coach at one time such as shore and generator power you can have phase issues. When coaches have a pair of inverters linked they automatically sync the phases so you get 60 HZ, but there is no means of doing that if you have other power sources supplying power.

[Dick]

I’m still wondering why Steve the OP wants to do what he proposed at the beginning of this thread. Why not leave the coach plugged into shore power?

[Tim]

Dick, After sitting in an R.V. park for 3 or 4 months I just wanted to exercise the generator under load for an hour. Thats all.

[Archived]

Got it!

[Brett]

Ahhhhh. I didn’t realize you were in the park that long. Now it makes sense to me. Thanks for clarifying.

[Tim]

Tim,

Even if not sitting at a park for a long time, you do want to execersie equipment. Folks who have roof AC’s, typically only use 3 on a daily basis so in order to run all 4 you must use Gen. And to exercise the GEN, you need to load it up.

So it’s just an exercise maybe once a month.

[glen]

We manage to run our generator more than once a month while traveling, since we usually boondock every few weeks while traveling.

I’ll be changing the oil/filter when we return to the farm in September …