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Generators: Can I use one Transfer Switch for two different generators?

Generators: Can I use one Transfer Switch for two different generators?

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  #1  
Old 01-31-13, 11:25 AM
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Generators: Can I use one Transfer Switch for two different generators?

Background:
Hi, I currently have a dual fuel portable 7,000kw (rated) generator. It runs on gasoline and has a conversion kit to run natural gas. I already have a sub-panel transfer switch hard wired to my portable generator. I do not yet have the gas line run to it. To attach the portable generator to the subpanel, I use a heavy duty plug/cord and plug it into an outlet outside beside the generator.

I'm also getting ready to buy a 6,000kw (rated) Generac Core Power standby generator. (quite small)


My questions are this:

1) When I install the Generac standby generator (right next to the portable generator) is there anyway to keep my portable generator (hardwired to a sub-panel) as a backup to the standby?

2) The gas line that will be run to the Generac is 1" and the conversion kit on the portable requires a .75" line. Is there an adapter I can use in the event I need to move the gas line from the Generac over to the portable generator? Or, is there a way to unscrew the 1" line and attach a .75" line at the meter with ease? I'm really dumb about gas line stuff.

3) Anyway to wire the portable generator into the Generac sub-panel and have some sort of A/B switch so I can use either device with the Generac transfer sub-panel?

Thanks for any assistance!
Robyn
 
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  #2  
Old 01-31-13, 12:12 PM
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Welcome to the forums!

1) When I install the Generac standby generator (right next to the portable generator) is there anyway to keep my portable generator (hardwired to a sub-panel) as a backup to the standby?
If you're asking whether you can use both at the same time, no.

2) The gas line that will be run to the Generac is 1" and the conversion kit on the portable requires a .75" line. Is there an adapter I can use in the event I need to move the gas line from the Generac over to the portable generator? Or, is there a way to unscrew the 1" line and attach a .75" line at the meter with ease?
Sure. I would install a 1" X 3/4" X 3/4" tee and two cutoff valves, plus drip legs, so that I could have the gas feeding to either one without disconnecting or connecting any lines. You may want to ask more about this specific question in our Plumbing forum.

3) Anyway to wire the portable generator into the Generac sub-panel and have some sort of A/B switch so I can use either device with the Generac transfer sub-panel?
That's called a transfer switch. It would mount between the inlets for the generators and the feed for the subpanel.

BUT, if your new generator is a true standby generator, and automatically starts itself and transfers the power supply when there's an outage, that won't work.

This is starting to sound like a lot of hassle just to transfer between two small generators. How much backup power do you need? What circuits and loads do you need to supply emergency power to? Why not just install a standby generator that will meet that demand?

You might have some of your questions answered by reading the sticky note at the top of the articles list for this forum: Congratulations! You have a Generator.
 
  #3  
Old 01-31-13, 02:18 PM
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Thanks for the detailed reply. I do not ever intend to run them at the same time. I only want to use the portable generator in case the standby generator fails. I'm looking for a way to be able to switch over from the standby (auto start) to the portable and still have access to the circuits that are wired into the standby sub-panel. So it sounds like the transfer switch should work for what I want to do I think.

Yes, the new standby will be auto start, but the scenario for using the portable one would be that the standby won't start up or if the natural gas supply is not available for some reason. Then I would like to be able to go to the basement to the sub-panel and switch the connection over to the portable. I would then go outside and start it up and still have access to all my essential circuits. Its kind of hard to explain exactly what I'm trying to do since I don't understand it 100%. Either one of the 7kw generators alone will run all my essential circuits.
 
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Old 01-31-13, 04:16 PM
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the scenario for using the portable one would be that the standby won't start up or if the natural gas supply is not available for some reason. Then I would like to be able to go to the basement to the sub-panel and switch the connection over to the portable.
OK, you need to install a transfer switch between the two generators and the auto-switch panel. The feed from the standby generator would be interrupted to go to one set of power-in lugs and the wiring from the inlet where you connect the portable generator would go the the other power-in set. The power-out set is connected to the auto-switch panel, of course.

Frankly, I'm not sure you can make this work. The standby generator is connected to its transfer panel with monitoring and control circuits. Switching to a different generator will defeat all of that, of course. It might also damage those circuits. I just don't know, and the manufacturer sure won't tel you.

Maybe there's a better way to spend your time and money. Doesn't Generac offer some sort of coverage for loss if its system doesn't do its job?
 
  #5  
Old 01-31-13, 05:00 PM
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I understand you explanation pretty well, but its making my mind smoke a bit! haha You're right this might be too much trouble. I have a koi pond and having a good warranty doesn't do anything for my fish so I'm trying to set up back ups to my back ups. I think I've got some good starting info to think about.

One last scenerio to consider, I already have a subpanel for the portable and if I install the second subpanel for the standby maybe that would work? I guess not though because you can only wire the desired circuits into one panel or the other right?
 
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Old 01-31-13, 05:18 PM
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I already have a subpanel for the portable and if I install the second subpanel for the standby maybe that would work? I guess not though because you can only wire the desired circuits into one panel or the other right?
Yep, that's right .
 
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