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Old 07-01-2021, 05:11 PM   #1
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30a shore power and generator same time

Question if hooked up to shore power and I want to test the generator will this cause any issues?

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Old 07-01-2021, 05:15 PM   #2
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It shouldn't. The generator has priority over the shorepower.

Of course if your transfer switch is mis-wired then it could cause an issue but when properly setup the generator has priority.
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Old 07-01-2021, 05:33 PM   #3
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X 2...
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Old 07-01-2021, 05:43 PM   #4
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Thx generator showed fault ..but restarted and all works. Cleared fault
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Old 07-01-2021, 06:11 PM   #5
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Thx generator showed fault ..but restarted and all works. Cleared fault
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Old 07-01-2021, 07:55 PM   #6
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It shouldn't. The generator has priority over the shorepower.

Of course if your transfer switch is mis-wired then it could cause an issue but when properly setup the generator has priority.
Funny this is brought up. My 2003 Hurricane, I tried to start my gennie yesterday while on shore power and all it did was make my generator buzz and wouldn’t turn over. Might have to do some checking.
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Old 07-02-2021, 02:55 AM   #7
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How old are your batteries?
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Old 07-03-2021, 05:50 PM   #8
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My batteries are 1.5 yrs. and always kept topped off. I’m assuming the generator uses the house batteries that is..
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Old 07-03-2021, 06:13 PM   #9
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Old 07-03-2021, 07:33 PM   #10
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It isn't required however I shut off my heavier electrical loads before starting the generator and then turn them back on

The transfer switch certainly (transfers) works under load but given the amount that fail I simply avoid that
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Old 07-07-2021, 03:32 AM   #11
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After having our transfer switch arc and melt wirenuts right from the factory, I have always tried to remove shore power before staring the generator. I know you "shouldnt" have to, however, an ounce of prevention...
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Old 07-07-2021, 03:57 AM   #12
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After having our transfer switch arc and melt wirenuts right from the factory, I have always tried to remove shore power before staring the generator. I know you "shouldnt" have to, however, an ounce of prevention...
SP has no bearing on the "melt wirenuts" issue. It's simply poor workmanship on installation.
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Old 07-07-2021, 04:43 AM   #13
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We always start up the generator while on shore power when I know we will be using the air conditioning and power on the road. Get the generator going everything runs off of that so I don’t have to turn everything off when I unplug. Haven’t had any issues knock on wood.
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Old 07-07-2021, 12:13 PM   #14
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Everyone who owns an RV should once a year disconnect all the power and remove the cover on the transfer switch and the AC distribution panel and check the tightness of all the screws on the circuit breakers and relays. They tend to get loose with time and all the temperature fluctuations and bouncing around on the road. Once the connection deteriorates it starts to overheat at high current levels which causes a further increase in the resistance and it over heats even more and this effect continues until the contact fails and sometimes a fire can start. Many a transfer switch has failed because the contacts were loose.

As far as starting the generator with the shore power connected, a properly working transfer switch will disconnect the shore power relay before engaging the generator relay. There is a small circuit board inside the transfer switch that is connected to both the shore power side and the generator side and has small relays that control the large relays. The transfer switch defaults to the shore power side but will transfer the power source to the generator when it is present.

Where we get into trouble when starting the generator with the shore power on is if the air conditioners are running with the compressors on at the time of the transfer. When the shore power relay is disengaged while the compressor is on you can get arching at the relay contacts because you are disrupting the current to an inductive load. The inductance of the motor will try to keep the current flowing by increasing the voltage between the contacts thus causing the arc and burned contacts. Once you do this a few times you have a bad relay. I would make it a habit to turn off the shore power before starting the generator just to be on the safe side.
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Old 07-07-2021, 03:26 PM   #15
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There are certainly lots of posts on the forum about failed transfer switches. Why temp fate by not turning off shore power?

All you'd have to do is be sure the AC is off, refrigerator off (AC), water heater off (AC) then start the generator.

I just think having shore power on and also running the generator is just asking for trouble.
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Old 07-07-2021, 04:00 PM   #16
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Originally Posted by bevedfelker View Post
There are certainly lots of posts on the forum about failed transfer switches. Why temp fate by not turning off shore power?

All you'd have to do is be sure the AC is off, refrigerator off (AC), water heater off (AC) then start the generator.

I just think having shore power on and also running the generator is just asking for trouble.
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Old 07-07-2021, 04:13 PM   #17
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Originally Posted by bevedfelker View Post
There are certainly lots of posts on the forum about failed transfer switches. Why temp fate by not turning off shore power?

All you'd have to do is be sure the AC is off, refrigerator off (AC), water heater off (AC) then start the generator.

I just think having shore power on and also running the generator is just asking for trouble.
The posts about "failed transfer switches" are more about the connection wiring rather than the transfer switch itself failing. And when the transfer switch itself fails the mechanism is either:
The control board failed so it doesn't switch to generator when the generator is running, or
Contacts are burnt so no connection is made.

There are zero cases of the transfer switch connecting the generator and SP at the same time.
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Old 07-07-2021, 06:26 PM   #18
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Quote:
Originally Posted by Bob Nodine View Post
Everyone who owns an RV should once a year disconnect all the power and remove the cover on the transfer switch and the AC distribution panel and check the tightness of all the screws on the circuit breakers and relays. They tend to get loose with time and all the temperature fluctuations and bouncing around on the road. Once the connection deteriorates it starts to overheat at high current levels which causes a further increase in the resistance and it over heats even more and this effect continues until the contact fails and sometimes a fire can start. Many a transfer switch has failed because the contacts were loose.

As far as starting the generator with the shore power connected, a properly working transfer switch will disconnect the shore power relay before engaging the generator relay. There is a small circuit board inside the transfer switch that is connected to both the shore power side and the generator side and has small relays that control the large relays. The transfer switch defaults to the shore power side but will transfer the power source to the generator when it is present.

Where we get into trouble when starting the generator with the shore power on is if the air conditioners are running with the compressors on at the time of the transfer. When the shore power relay is disengaged while the compressor is on you can get arching at the relay contacts because you are disrupting the current to an inductive load. The inductance of the motor will try to keep the current flowing by increasing the voltage between the contacts thus causing the arc and burned contacts. Once you do this a few times you have a bad relay. I would make it a habit to turn off the shore power before starting the generator just to be on the safe side.
Good stuff...
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Old 07-07-2021, 07:50 PM   #19
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Quote:
Originally Posted by Bob Nodine View Post
Everyone who owns an RV should once a year disconnect all the power and remove the cover on the transfer switch and the AC distribution panel and check the tightness of all the screws on the circuit breakers and relays. They tend to get loose with time and all the temperature fluctuations and bouncing around on the road. Once the connection deteriorates it starts to overheat at high current levels which causes a further increase in the resistance and it over heats even more and this effect continues until the contact fails and sometimes a fire can start. Many a transfer switch has failed because the contacts were loose.

As far as starting the generator with the shore power connected, a properly working transfer switch will disconnect the shore power relay before engaging the generator relay. There is a small circuit board inside the transfer switch that is connected to both the shore power side and the generator side and has small relays that control the large relays. The transfer switch defaults to the shore power side but will transfer the power source to the generator when it is present.

Where we get into trouble when starting the generator with the shore power on is if the air conditioners are running with the compressors on at the time of the transfer. When the shore power relay is disengaged while the compressor is on you can get arching at the relay contacts because you are disrupting the current to an inductive load. The inductance of the motor will try to keep the current flowing by increasing the voltage between the contacts thus causing the arc and burned contacts. Once you do this a few times you have a bad relay. I would make it a habit to turn off the shore power before starting the generator just to be on the safe side.

Is there a typical place to look to find the transfer switch? My owner's manual does not provide that info.

Thanks, Dan
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Old 07-07-2021, 08:07 PM   #20
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Is there a typical place to look to find the transfer switch? My owner's manual does not provide that info.

Thanks, Dan
Dan,

It is usually as near as practical where the shore power cord enters the RV. I see you have a Four Winds which could mean it is under the bed or near a compartment where the shore power enters the coach. On our Quantum the transfer switch is accessible by removing a panel in the compartment near where the shore power connection is. In the attached photo you can see the transfer switch. The module in the upper left corner is the slide controller and the box at the bottom is just a junction box.
***********
I just noticed the photo somehow got rotated 90 degrees counterclockwise. In that case the slide controller is the module in the lower left corner.
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