Plugged in and Generator

I know that you can start the generator while plugged in, but as a precaution I never do. The transfer switch can glitch and cause an issue. When I had my Monaco Diplomat, I started the generator while on shore power one day while working on the coach. Something hung up and blew the circuit breaker on the generator. I never did it again, just not worth taking a chance on the switch over occurring like it should, unnecessarily.

2oldman wrote:
Please enlighten us.. why would you be doing that?

We have done that.
Sometimes where we are parked only has a 15A outlet. If I need to run the microwave, I will run the generator. Because the generator provides higher amperage than the 15A, the EMS switches to the generator for power. We have done this dozens of times, but only when plugged into 15A shore power. We never start our generator under load, but the EMS takes care of that too: it turns on each major appliance one by one over the course of about two minutes so as not to overwhelm the generator (WH, AC1, AC2, fridge, fans) in case they were left on.


We have also run the engine when the generator is on with no problems.

my start stop switch in the dash shorted and the generator was running when I came back from fishing , shore power was plugged in, the dash switch would not shut the gen set off had to roll the generator out to access the switch on the gen set to shut it off. after a new switch from American coach have not had any problem for the last 5000 miles

mtrumpet wrote:

dougrainer wrote:
With Transfer switches, it is NEVER a good idea to transfer power under any load. Regardless of Shore Power or Genset. The reason is, there are contac points in a transfer switch and transferring under load will cause those points to arc and slowly build up deposits on those points until one day they fail to make contac even tho they close. The best way to transfer is to turn the MAIN breaker OFF at your inside Breaker panel and then either connect to Shore or allow the Genset to transfer, then turn the breakers ON. There is NO system out there that if wired to code will cause a problem (hazard), by turning the genset on when connected to shore power. Or Vice/Versa. Doug

When I attended an Onan Generator seminar a couple of years ago, they were very insistant about NOT starting the generator while plugged into shore power and not plugging into shore power while on generator power.

That is just a CYA statement. I have probably started Gensets on thousands of Motorhomes with shore plugged in in the past 37 years. It IS a good practice, but I doubt that less than 1 percent of RVers ever do it. Doug

dougrainer wrote:
With Transfer switches, it is NEVER a good idea to transfer power under any load. Regardless of Shore Power or Genset. The reason is, there are contac points in a transfer switch and transferring under load will cause those points to arc and slowly build up deposits on those points until one day they fail to make contac even tho they close. The best way to transfer is to turn the MAIN breaker OFF at your inside Breaker panel and then either connect to Shore or allow the Genset to transfer, then turn the breakers ON. There is NO system out there that if wired to code will cause a problem (hazard), by turning the genset on when connected to shore power. Or Vice/Versa. Doug

When I attended an Onan Generator seminar a couple of years ago, they were very insistant about NOT starting the generator while plugged into shore power and not plugging into shore power while on generator power.

Moffittclan wrote:

DrewE wrote:
Others have answered the generator question. There's no difficulty with starting the coach while plugged into shore power. Of course, actually driving away while plugged into shore power is quite problematic.

Haha, When I was having an issue getting the coach to turnover, one of my first thoughts was, "I'm still plugged in...I wonder if there is a safety cut-off switch that prevents you from starting the coach while plugged in so you don't drive off..." Still troubleshooting but it looks like it will end up being bad batteries that kept me from getting it started...

Never been such a system on motorhomes. Doug

DrewE wrote:
Others have answered the generator question. There's no difficulty with starting the coach while plugged into shore power. Of course, actually driving away while plugged into shore power is quite problematic.

Haha, When I was having an issue getting the coach to turnover, one of my first thoughts was, "I'm still plugged in...I wonder if there is a safety cut-off switch that prevents you from starting the coach while plugged in so you don't drive off..." Still troubleshooting but it looks like it will end up being bad batteries that kept me from getting it started...

Others have answered the generator question. There's no difficulty with starting the coach while plugged into shore power. Of course, actually driving away while plugged into shore power is quite problematic.

gbopp wrote:
The automatic transfer switch does a good job. But, I always unplug from shore power before I start the generator. Just in case.

X2

Most genset setups have the generator running for some period of time - usually 10-15 secs - before the field kicks in and it starts generating electricity. Then there's a 5 sec delay before the transfer switch will switch over IF it's designed to favor generator over shore power. The only reason yours would not behave this way is if someone got into the wiring and screwed something up.

Just running the generator is ok, but you should be running it under load occasionally to dry out the stator windings. To do this you'll need to start the gen and switch off the shore power, then start something in the coach that will draw a few amps. I use the clothes dryer or a ceramic heater.

Flipping on the inverter before doing all this will prevent power outages that would require you to reset clocks, etc. Remember the 5 secs delay before the transfer switch switches to generator.