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120V question this time

We're visiting some friends for the weekend. All we have for an electric source is a 20A outlet or our generator. Since it is warm we're running the generator during the day, and will probably let it rest overnight. Can I leave the coach plugged into their outlet when the generator is running, or should I unplug during the day? My concern is twofold: I don't want to trip their breaker during the day when we want the a/c on and I don't want to be back feeding into their house.

Re: 120V question this time

Reply #1 –
Your automatic transfer switch should choose the power source.  Depending on how it's set up it will give preference to only one power source.  When the genny is running you must be isolated from the outside source as a safety measure as back feeding the utility will cause a hazard to their lineman.  The transfer switch should accomplish this.


Keith


Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: 120V question this time

Reply #2 –
Yes, the ATS SHOULD (again SHOULD) properly switch to generator ONLY when the generator is running.  But, at that age, I would not count on how an ATS is wired. And, really no reason to ASSUME that it works perfectly every time.

It is very little more work to unplug from shore power before starting the generator and then turning off the generator before plugging in.

Just playing it conservative. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 120V question this time

Reply #3 –
Transfer switches are setup two ways:  Shore-priority OR generator-priority.
When both shore power cable is plugged into live outlet AND generator is running, shore-priority will not use generator power and generator-priority will not use shore power.  So if your coach transfer switch is shore-priority, like ours, you have to unplug cable to use generator power.  We did add an inside switch to 'fool' our transfer switch into thinking our shore is unplugged, which we can use if needed.
There should never be a back feed from generator to shore power plug, but unplugging shore cable will prevent you from turning on high-current devices like hair dryer, microwave, roof air, refrigerator, hot water, etc and tripping shore plug breaker.
Also all high amperage loads should be turned off before switching between gen & shore, to prevent transfer switch 'damage'.

Re: 120V question this time

Reply #4 –
There is a  large risk in transferring shore power to gen power instantaneously  (or vice versa) when you have heavy loads connected (AC or microwave, etc) ..that will pit the transfer switch relay contacts over time. It would be best to unplug one source before starting another source or at a minimum, shut off any heavy loads first.

Jim
Jim Frerichs
2002 U320 42'

Re: 120V question this time

Reply #5 –
I love my MANUAL transfer switch!

TOM
SOB (Some Other Brand) division
1995 Wanderlodge WB40
8V92 :D

Re: 120V question this time

Reply #6 –
Last night I shut off the generator, then stretched out the cords and plugged in. Later today I'll unplug from the garage and then start the generator. I'm guessing that I probably could just turn the inverter on and not even bother with being plugged in, but then I couldn't use the computer (this isn't a laptop) and Jo Ann couldn't have the television on.

Re: 120V question this time

Reply #7 –
Quote from: kb0zke –
I'm guessing that I probably could just turn the inverter on and not even bother with being plugged in, but then I couldn't use the computer (this isn't a laptop) and Jo Ann couldn't have the television on.
You could just purchase one (or two) small portable pure sine inverters to run computer and TV.  They are not expensive, and can be moved around as needed.  Just add a hard-wired 12 volt lighter socket in the areas where you would need the inverter (150 watt draw or less).

Something like this, perhaps?
Amazon.com: Wagan EL2601 Elite 400W Pro Pure Sine Inverter: Automotive
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 120V question this time

Reply #8 –
Quote from: OldManSax –
I love my MANUAL transfer switch!
What kind of switch does your 'Bird use, Tom?

I purchased a Blue Sea 9019 switch a while back, but have not yet installed it.  I plan to replace our ATS with the manual switch.  My primary motivation is the desire to eliminate the "humming" noise of the ATS - my wife and I seem to be especially irritated by that particular frequency (yes, we are strange).  Secondary reason is to simplify the switching hardware.  I always manually shut down all loads before switching between shore power and generator, so I believe the "protection" function provided by the ATS is simply not required.

Yes, I know - the ATS works fine, and it's dumb to spend good money to replace a automatic switch with a manual one, yada, yada, yada.  I'm not suggesting everyone do this...it's just something I feel will work out better for us.  That's the name of the game, right?

Amazon.com : Blue Sea Systems 9019 Switch, AC 240VAC 63A OFF +2 Positions :...
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 120V question this time

Reply #9 –
We leave our inverter / charger 'on' all the time, and when we unplug or turn off gen, all of our electronics including Directv DVR automatically switch to be run inverter power, and when we use gen or plug back in, the stuff switches back to shore or gen.
ALL high amp plug-in devices like microwave, space heaters, hot water tank heater, vacuum, etc are plugged into outlets that are NOT on inverter, so when switching from shore / gen, these devices shut down.

Re: 120V question this time

Reply #10 –
Quote from: Barry & Cindy –
We leave our inverter / charger 'on' all the time,
It may be prudent to turn off the inverter if the coach is being stored rather than being occupied. If shore power fails for more than a day, the house batteries are more likely to suffer significant discharge if the inverter is on.

Fulltimers, such as  Barry & Cindy, will normally be with their coach all the time and can personally manage the power in case of a failure of shore power. We also leave the inverter on most of the time when we are living in the coach. I do sometimes turn it off during "sleeping hours" if we are operating from battery power.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: 120V question this time

Reply #11 –
I can run 1  A/C off a 20amp outlet (and probably a 15amp too). One of my A/C is usually around 12-15amps draw, depending on temperature outside, voltage, etc. It's cutting it close with the battery charger on.
1998 U270 34'

Re: 120V question this time

Reply #12 –
Quote from: krush –
I can run 1  A/C off a 20amp outlet (and probably a 15amp too). One of my A/C is usually around 12-15amps draw, depending on temperature outside, voltage, etc. It's cutting it close with the battery charger on.
I also can run 1 ac and refrigerator on 15/20 amp ac.  Generally turn charger portion of inverter off.  You can run microwave,
toaster, coffee pot etc also, just turn ac off and run one at a time.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: 120V question this time

Reply #13 –
Outside the main breaker panel in front of the bed , we put a male 15-amp plug on rear roof air wires, and a female 15-amp socket to the breaker that the roof air wires were connected to.

Normally the socket and plug stay connected.  But when only 30-amp / 20-amp campground outlets are available, voltage is low, temps are hot, etc, we can plug the rear roof air into a 2nd extension and easily run both A/C's.  This works with GFCI  outlets.

We have used this setup a couple times a year.

Re: 120V question this time

Reply #14 –
Quote from: Chuck & Jeannie –
What kind of switch does your 'Bird use, Tom?

Chuck,

I don't know!  LOL! Sorry! 

It's over kill for what you want though. It has 4 positions, OFF, GEN, 50A, 30A.  That's because it has a both a 50A connection and two 30A connections.  If I am in a place that only has 30 amp service, I have two 30A power cords so I can connect to two different 30 amp connections.  The 30A position on my transfer switch feeds one 30A connection to one leg and the other 30A connection to the other leg, giving me 30A on each leg, assuming the supply itself has that much capacity.  I am going to remove all of that eventually and replace it with two 100 amp contactors so I can simplify the wiring.

The TS you linked to should do what you need with no problems.

TOM

The one you linked to should
SOB (Some Other Brand) division
1995 Wanderlodge WB40
8V92 :D