2 Generators common neutrals

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Old 01-19-16, 10:52 AM
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2 Generators common neutrals

I have two portable generators, 1 for the needed circuits in the house and 1 that I plan on powering my AC unit during the summer months. I have all my needed circuits connected to an 6 circuit man x-fer switch being powered off one generator. For the AC, I have planed to install a single circuit manual x-fer switch powered from another generator. The installation instructions for both x-fer switches are pretty straight forward as both call for ground wire to ground bar and white wire to neutral. Using 2 different generators at the same time, are the neutrals/grounds going to be a problem? Thanx!
 
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Old 01-19-16, 01:16 PM
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It shouldn't be a problem as long as the house service is properly grounded.
 
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Old 01-19-16, 07:40 PM
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1 for the needed circuits in the house and 1 that I plan on powering my AC unit during the summer months.
Unless the A-C is a window unit or smaller mini-split unit you won't need a neutral for the A-C. Central A-C condensing units are 240 volt.

Your furnace/air handler will have to be powered from the other generator.
 
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Old 01-19-16, 08:23 PM
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Just be sure that there are no 240 volt appliances connected to a hot of one generator and a hot of the other generator.

There is no assurance that the two generators will stay synchronized and trying to obtain 240 volts by using two 120 volt generators will give unpredictable results.
 
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Old 01-20-16, 09:59 AM
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As AllanJ mentioned, synchronization is a problem. Some generators are designed so they can be paralled, but some are not. A generator's frequency can vary based on its load and loading one generator heavier than the other may worsen any sync difference. Contact the manufacturer to see if they make a sync cable for that model.
 
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Old 01-20-16, 12:12 PM
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Synchronization is irrelevant in the OP's situation. He is running different appliances on different transfer switches. The hots are not connected. The question is about the neutrals being interconnected by virtue of how transfer switches connect to the service panel.
 
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Old 01-20-16, 12:22 PM
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Do either/both of your generators have built in GFCI protection?
 
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Old 01-20-16, 02:10 PM
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I do not see a GFCI on either of the generators. One of the manuals has "Neutral Floating" on its cover and the other units manual says to connect unit to a ground rod prior to use. Are these of any help?
 
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Old 01-20-16, 08:39 PM
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With each generator controlling different equipment, it does not matter if the neutrals are interconnected.

Neutral floating means that the neutral is not connected to the generator framework.

In most cases the generator works equally well whether or not the neutral is connected to the frame.

In the field (not connected to a building electrical system), neutral is supposed to be connected to the frame. The instructions probably shows how a jumper may be connected within a floating neutral generator to connect the neutral to the frame.

For most building use, it is better if the neutral is not connected to the generator frame. If the transfer switch and panel wiring is such that the neutral is connected to ground in one of those locations then it is better if neutral is not connected to the generator frame.
 
 

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