Running house on generator, theory question?

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  #1  
Old 10-15-07, 04:41 AM
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Running house on generator, theory question?

OK so I know a little bit about basic electrical wiring and have a question regarding a generator and using it to partially power my house during outages.

I have an outside RV plug installed on the side of my house. It is ran off of 10gauge wire with a single pole 30amp breaker. My theory is that during an outage, I could turn off my main 100amp breaker to my house, hook my generator up to the outside RV plug and feed electricity from my generator through the RV outlet and power my panel.

Now I would not want to power my whole panel, just some of the things like furnace, lights, and maybe refridgerator. I would turn the breakers to the heavy duty items off like AC, range, dryer, those types of things.

So would this work? Like I said I would turn off the main breaker first as to not send any unexpected electricity back through the system to some poor worker down the line. My generator is also a 5500 watt gen, that is also why I say I would not be running any of the big things on my panel, those breakers would be off. Is my theory possible? Safely possible?
 
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  #2  
Old 10-15-07, 04:58 AM
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Unless you have a method to ensure that the main is off when the generator is running, I believe it would be illegal. I think a manual transfer switch would probably be your best bet.

From a practical standpoint what you are proposing *could* be safe. However it only takes one time of forgetting to turn off the main to fry some poor guy fixing your power.
 
  #3  
Old 10-15-07, 05:36 AM
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What you propose is called back feeding your main panel. It is illegal and dangerous. If you forget, just for a few seconds, to shut off your main breaker, you are putting electricity back on the main line and you could kill someone.

Your plan is also flawed because is uses a double ended male cable so that you can connect the receptacle on the generator with the receptacle for the RV.

The only legal way to make this connection legally and safely is to use an appropriate inlet (ie a plug on the side of the house) that connects either to a proper transfer panel or attaches to breaker in your panel that cannot be in the on positon at the same time as the main breaker. They sell circuit breaker interlock kits that can be installed for this purpose.

A transfer panel is a panel where you install SOME of your house circuits (those you would want to have power in a power outage). It can be fed either
from the main panel or from a generator connected up, but not both at the same time.
 
  #4  
Old 10-15-07, 07:36 AM
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I appreciate the feedback so far. I will first say that I certainly will not do anything illegal or unsafe with this scenario. As I am still learning about electrical wiring, I ask some of these questions just in theory.

racraft, you say that the plan is also flawed because I would be using a double ended male plug to make the generator connection, why is that bad? Again just in theory would this setup function? What I mean is say I as long as the items I was powering didn't exceed the 30amp rating of the RV breaker would it be safe along the lines of a fire type hazard? Will a breaker trip regardless of which way the electricity is flowing through it?

I am still in the begining stages of learning about this stuff, that is why I ask these hypothetical questions. Thanks!
 
  #5  
Old 10-15-07, 07:56 AM
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A regular breaker will trip regardless of which way the current is flowing. I do not, however, know about GFCI or AFCI breakers.

A double ended male cord is dangerous. It means that, depending on how it is used, that you have the prongs of the plug exposed and capable of causing electrocution. While you can obviously make such a cord, you cannot buy one from a reputable source.

The other problem with your scenario is that your generator is a 5500 watt generator. This most likely means a 20 amp 240 volt output. You want to connect this to 30 amp receptacle. 20 amps does not equal 30 amps, and the ends of your cord would have plugs rated for two different amperages.

The scenario you you are asking about is used all too often by people when the power goes out. This is why power company (and other utility) workers consider every wire charged, even when they "know" the utility power is off.

One final comment. If you accidentally left your main breaker on and were getting away with it (ie it was still running despite putting power out to the grid), when the power company did restore power, your generator would likely be ruined as it would immediately be forced to be synchronous with the power company.
 
  #6  
Old 10-15-07, 09:30 AM
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Aside from being dangerous and illegal you can only power half your house from that receptacle. You said it was single pole 30 amp. Back feeding it would only power up one side of your panel and no 240 devices would operate.
 
  #7  
Old 10-17-07, 07:50 AM
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"Back feeding it would only power up one side of your panel and no 240 devices would operate."


Not totally accurate. The other buss would be powered by the return line of any of the 240V loads at a reduced voltage, which could cause some serious equipment damage.
 
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Old 10-20-07, 07:57 PM
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Reduced Voltage

Please explain how he would have voltage on the B phase.
 
  #9  
Old 10-20-07, 08:08 PM
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Please do not use the term phase. It is incorrect and confuses people.

Current will flow through 240 volt appliances, like an electric water heater. There is nothing to stop it from flowing.
 
  #10  
Old 10-20-07, 09:15 PM
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What is wrong with the term phase?
He said that he was turning off the 240 volt loads.
 
  #11  
Old 10-21-07, 07:16 AM
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The two feeds to a residence are not phases, they are actually the same phase of power from the power company. The appropriate term is leg.

Phase means something entirely different. I know that people use the term phase, but it is wrong and propagates the issue.
 
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