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Home Generator- Connecting to the house

Posted by jstillw (My Page) on
Thu, Sep 8, 05 at 22:17

Just purchased a Snapper 6200 Watt generator for emergency power. We live in the south and only lose power for long periods from weather (hurricanes).

I have looked over the forums about connecting the unit to our home and still feel confused about the dangers.

The equipment store that sold us the generator has had quite a few customers run the following system (they say is not legal, however works well and is safe).

Generator with output socket 240/ 30 amp

1. Make a power cord with a 30 amp male plug (goes into generator) and another male plug that will fit your 240v dryer outlet. Use 10 gage 4 pole wire.

2. Shut off the main breaker (very important).

3. Turn off all breakers on the panel.

4. Hook up your power cord to the generator. Unplug the dryer and plug in the other end into the dryer outlet.

5. Start the generator.

6. Turn on only the breakers that you will be using (know which ones go where and make sure labeled).

They say you are running a safe system that will not backfeed the main power grid and hurt a tech. They say the breakers in your home will do their job.

This system costs about $70 in cable and connectors. You could also place a 240v outlet near where the generator will be used and plug in there. Running in this case a 30 amp breaker from the main to the outlet.

This sounds safe, as long as you have switched off the main breaker.

Can I get feed back on:

1. Does shutting off the main breaker prevent feedback to the power grid???
2. Is the house protected by the breakers in the main box so as not to start a fire???


Follow-Up Postings:

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RE: Home Generator- Connecting to the house

The answer to question number one is yes as it was told to me. Not sure about question number two.

Doug


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RE: Home Generator- Connecting to the house

I'm not an electician, but I will tell you what I know.

1. Shutting off the main should prevent backfeed, unless your main is not set up correctly to begin with, which is always possible. I have read about feedback even when the main was shutoff.
2. There is a danger of overloading the circuit you are plugged into if your generator is putting out more amps than that wire can carry, and that could cause overheating and a fire before it gets to the main.

If you forget to shutoff the main you can KILL somebody. Not just hypothetical, but actual. A search of the internet will reveal stories of linemen getting killed.

Some who do backfeed try to justify it by saying they won't forget to shutoff the main, and linemen should be properly grounding and testing before they handle the wires. Well fine, but that just leaves you 2 mistakes away from killing someone. Both of those mistakes can and do happen.

A transfer switch, by design, does not allow the generator to backfeed through the main. It doesn't rely on you to remember to switch anything. The transfer switch mechanically either allows your selected house circuits to get power from the main or to get power from the generator, but not both at the same time. It is dummy proof.

Another reason to have a transfer switch is so you can manage your loads. For example, if you have a 6 circuit transfer switch. One leg of the 240 feeds circuits 1-3, and the other leg feeds circuits 4-6. You balance the draw when you assign those circuits, and you have 2 meters on the transfer switch to view the draw off of each leg. In order to run a 240, you tie circuits #3 and #4 together so you are drawing from both legs.


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RE: Home Generator- Connecting to the house

Another danger with the proposed method is having 30 amps at 240V on the end of a male plug. There's a reason why the powered side of an outlet or cord is female.

Spend the money and have a transfer switch installed, or run extension cords.


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RE: Home Generator- Connecting to the house

Another reason for a transfer switch is ease of operation.

You spend good money on a generator, so assume you want to keep it well maintained and ready for when you need it. If so, then you need to run periodically, perhaps monthly, under load. If you don't run periodically, not only will you likely have trouble with the engine, such as gumming the carberator, having stale gas, etc, but the generator can lose its charge.

With a transfer switch, you don't need to turn off your main. Instead, while the rest of the house is running normal, you just plug in your generator and power any of the transfer switch circuits under load for 15 minutes or so.

Also, the way a transfer switch works, you will always know when power comes back on in your house because the main is never turned off.


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RE: Home Generator- Connecting to the house

Thanks for all the updates.......

We should be building a new home starting within the year. This one will have the transfer switch built in. I don't think we will need the generator for powering our current home, however you never know with the hurricanes. For a short period I will most likely just use it with heavy duty extention cords. I have the backup power cord made to backfeed and can easily convert the male end to female and plug into the new transfer system on the new house someday.

By the way the 10 gage four pole power cords sure are expensive. Runs around $70 for a 25' in the box premade one. I built mine with around 35' for the same price and is very easy to do. Same system as wiring a line for your home dryer.

Again thanks for everyones help.


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RE: Home Generator- Connecting to the house

Bear in mind that utilities take back feeding very seriously. If they find voltage on a line which is supposed to be dead, (1) they will search the neighborhood for houses which are lit up, ask to see your transfer switch, and if you don't produce, (2) they will report you to code enforcement.

If one of their men is injured, skip step two, and go directly to lawyers. The burden of proof is on you, and your liability is nearly unlimited, to the extent of your net worth,


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RE: Home Generator- Connecting to the house

What is a transfer switch, how is it installed and how much does this generally cost?


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RE: Home Generator- Connecting to the house

One of the problems with panel disconnects is that they are of the 2-pole variety, not 3-pole.

While it is true that they disconnect the two hot leads coming into the panel, they do not disconnect the neutral lead. There have been instances of power backfeeding into the neutral and since the neutral is directly connected to the outside feed, you can see the danger that can ensue.

The best way is the safest way and in this case, the safest way is to take out an electrical permit and have the transfer switch installation inspected by the proper authority.


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RE: Home Generator- Connecting to the house

  • Posted by canguy British Columbia (My Page) on
    Sat, Dec 9, 06 at 0:28

dramswin13, a transfer switch cuts off the line feed and switches over to standby when the grid is off and the generator is running. It switches back when the grid power is restored. It's main fuction is to prevent the standby or grid systems from feeding each other.
Do NOT try to power the house by backfeeding an existing circuit. As has been mentioned, this is a good way to start a fire. What is your home and your family's security worth?


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RE: Home Generator- Connecting to the house

Remember Murphy's law - "If anything can go wrong, it will." The system needs to be designed so it cannot be connected the wrong way.

dramswin13, the linked web site has some answers to your questions.

Here is a link that might be useful: transfer switch info


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RE: Home Generator- Connecting to the house

Jeffrey_ wrote:

"1. Shutting off the main should prevent backfeed, unless your main is not set up correctly to begin with, which is always possible. I have read about feedback even when the main was shutoff."

It is possible. However, almost all of the accounts of backfeeding with the main off are urban legend. Its VERY unlikely that it would happen. Its also VERY unlikely that your generator breaker wouldn't pop within a second if you started to feed power to several houses with a portable generator.

"2. There is a danger of overloading the circuit you are plugged into if your generator is putting out more amps than that wire can carry, and that could cause overheating and a fire before it gets to the main."

No there isn't. The dryer circuit breaker in the panel will protect the circuit just like it would when providing power from the other end. Besides most portable generators also have 20 or 30 amp breaker on their 220v output.

That said I think backfeeding is a bad idea.


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RE: Home Generator- Connecting to the house

If you're going to do whole-house power, do it the right way and install a darned transfer switch. It is a $200 unit plus installation, which you can do yourself if you trust your electrical wiring abilities. I helped a friend install one a couple years ago and it was a nice leisurely Saturday project.


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RE: Home Generator- Connecting to the house

Northern tool carries transfer switches. Make sure your transfer switch carries the same amps as the biggest outlet on your generator. Keep in mind if you buy the transfer switch, cables etc on your own, you might have trouble finding an electrician to do the work without charging an arm and leg. If the electrician isn't going to make a profit on the parts expect to pay more for labor.

http://www.northerntool.com/webapp/wcs/stores/servlet/NTESearch?storeId=6970&N=0&Ntk=All&Ntt=transfer switch&Nty=1&D=transfer switch&Ntx=mode+matchallpartial&Dx=mode+matchallpartial


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RE: Home Generator- Connecting to the house

It sounds like a generator would cost a arm and a leg, to do it correct and legal. I'm in a 78 single wide mobile home RENTAL and can't see the effort. My only concern is the lack of heat. I can use my camp stove for cooking, oil lamps, propaine lamps and a (D-Cell light, for the childs room.) Battery backup radio for news and walky talkys with the weather station and 12V blankets.

My concern is the lack of heat.

It seems to me that the new propaine heaters that they sell at R/V shops that don't use O2 or put off carbon monoxide would be a better bet. Less expensive and portable.

Provided there are no leaks would there be a problem with the can inside the house?????

I saw on the news today someone burned down there house, using a inverter from there car to power up there house. So we now know that's out! Any feed back is welcome. There are over one million people with no power from the wind storm we just had in WA. and OR. on 12/14/06. Nothing like frozen shave cream!

Here is a link that might be useful: My Bebo Link.


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RE: Home Generator- Connecting to the house

I've never heard of a propane heater that doesn't use oxygen or put off carbon monoxide.

If you mean a remote type "tent" heater, I doubt it would provide enough heat for a house or trailer. You might be able to heat 1 room, but that's about it. Even then, you have to provide an opening through a window or wall and that usually lets out more heat during "normal" days.


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RE: Home Generator- Connecting to the house

Here's some live video of the "Don't's people are doing.

Copy and paste if you need to:

http://www.nwcn.com/sharedcontent/VideoPlayer/makeASX.php?title=www.king5.com/ki_121806shoreline_housefire.wmv&adurl=adcontent/Vicks44_Inferno_111406.wmv

Here is a link that might be useful: King 5 News Video Feed.


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RE: Home Generator- Connecting to the house

New question.......We are in the process of purchasing a log cabin on 40 acres that is not connected to grid power, however, it is powered by a solar setup. The batteries that power the cabin are dead, due to not being used for years. I would prefer to not invest in new batteries if possible, as the cabin will be used once a year at most and is very remote. I would prefer to hook up a generator directly to the fuse box without hooking up a manual transfer switch. Is this possible and if so how is it done? There is also currently an converter hooked into the fuse box that I would like to keep in place.

Any thoughts would be appreciated.

Many thanks.


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RE: Home Generator- Connecting to the house

  • Posted by canguy British Columbia (My Page) on
    Sat, Jan 27, 07 at 23:20

What do you mean by a converter? You probably have an inverter which inverts the DC from the batteries to AC which is the same as provided by the grid. You will not need it with the generator as it provides AC. In your situation, you certainly can hook the generator directly to the main panel.


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RE: Home Generator- Connecting to the house

Thank you. Is direct wiring to the main panel easy. Or is it something I should have an electrician do?

Thanks.


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RE: Home Generator- Connecting to the house

My reply is based upon the following facts.

1. There is no connection from the local power grid to your cabin.

2. The person that originally wired this cabin, followed the standard practices of the trade and the work conforms to the electrical code, including.......proper grounding of all aspects of the system.

3. And that the existing wiring system in the cabin was set up to receive 120/240 volt AC grid power at some point in the future, if it became available.

The way I see it, you have two choices. You can either use a "whole house" transfer switch that will allow you to choose between the existing solar power supply or the genset.

OR...... you can simply disconnect the wires from the solar power supply and tape them off inside the main panel for your cabin (fuse box/breaker box). You don't need to actually remove the wire from the fuse box itself. This would allow you to easily reconnect the solar power supply system in the future, should the need arise.

The purpose of a transfer switch is to provide 100% isolation between two differing sources of power. So, one way or the other, this isolation must take place. IF you don't isolate the solar system from the genset, then the genset will feed power back into the solar supply. Damage may be done but even if it does not do damage, the solar system is a potential loss of wattage from your genset and you could also have a fire and electrical hazard.

Once you disconnect the wires from the solar supply unit, you can install the correct wiring between the fuse box and wherever you are placing the genset. If your panel is a standard residential fuse or circuit breaker panel, then it requires 240 volts plus a neutral wire to connect to the genset. You also need to make sure that all grounding issues are taken care of. Some how, your genset must be grounded to the cabin's system.

If you are not sure of how to go about this, then hire a licensed electrician to perform the work. Better to be safe, than electrocuted.

You also need to consider that many gensets use about a gallon of gasoline per hour of run-time. If it was me, I would be looking at a diesel genset so that I could install a lockable fuel oil tank in the 250 to 500 gallon size on the property. The thought of transporting several five gallon cans of gas in my car wouldn't thrill me. No matter how hard you try not to, you will spill fuel from those containers. Gasoline is a highly inflammable and explosive fuel. You don't want those fumes inside your vehicle.

Having a permanent tank that is refueled by a company with a tank truck has many benefits. Plenty of reserve fuel that is far more stable than gas and no worries about refueling a hot engine.


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RE: Home Generator- Connecting to the house

This is an interesting topic. I have just found something on the web that may change some of the thinking. Technically, you could add a 30,50 or 100 amp circuit breaker to your main box and run it to an outlet with a male plug. Then run a power cord from the male outlet to your generator. The jumper would have a female end for the outlet box and a male end for your generator. Obvioully there are two problems. 1. backfeed 2. potential of the male outlet being energized. Well I just saw on the web a NEC approved generator interlock for use in the main panel. Apparently it slides (direction dependent on your box design) to assure the main breakers are off before it switches the generator breaker on. Take a look and provide comments. the link to the product is
http://www.interlockkit.com/
This has always been a great forum.

Here is a link that might be useful: Generator Interlock Technologies


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RE: Home Generator- Connecting to the house

I am rebuilding my home 30 miles north of New Orleans. The interlock looks good $20 to $150 what a swing ouch! Is it legal to use panel main as disconnect. I want service grade 200 amp double pole double throw. NEC says the neutral carries through. Some gensets have GFI outlets would this trip it. Should I use triple pole switch.


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RE: Home Generator- Connecting to the house

I had my electrician set my system up with one of the interlock systems, but not that one. The one above is sturdier than mine. Anyway it mechanically prevents activating the 220 volt breakers wired to the generator from being activated until the main breakers have been switched off.
The advantage of this besides dramatically lower cost, is that any circuit can be activated. The transfer switch has to be wired for specific circuits and you are stuck with them only.
The disadvantage is you don't know when power is restored without checking the meter. I'm thinking of wraping a few coils of wire around the hot lead and inducing enough current to drive an led run up to a window to indicate power restoration.


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RE: Home Generator- Connecting to the house

I was told the same thing about backfeeding and how to make up the needed wiring and plug, but somehow had the little voice keep saying don't do it!!! Our Electric Coop and Newpapers have repeatedly put out that it is illegal....and lineman can be seriously injured or killed. This latter part got me - yesterday I had an Electrician out and he is going to put the transfer switch in and fix the set up so I can hook up my generator on my covered porch. I know I will sleep a lot better with it done -- hopefully never needing it.


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RE: Home Generator- Connecting to the house

Re: Covered porch!! Will that covered porch be completely closed in for winter?? If you have it that way, carbon monoxide can and will seep into the house, by sneaking thru poorly maintained weatherstripping around the doors and/or windows!
I have a small generator that i keep on the front porch, in case of a power failure. my wife needs an oxygen machine sometimes. The porch is open, and i run the plug out thru a window. Our power outages are usually not much longer than a few hours, and i do not go to bed with it running. I seal around the window with heavy rags, etc.
And, i do not try to make up a double male plug extension cord! NO-NO!! Not wanting to languish in Federal prison doesn't tempt me to do that!


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RE: Home Generator- Connecting to the house

Rusty, the porch is 14X30 and screened. I need the oxygen fulltime and our outages have gone from a few hours to a couple of days.
You can bet I will not loose power ever....now that I spent the bucks for the switch box, ha!! But I really feel it is a great insurance policy - we are remote, so we would not have water without electricity.
BTW, I found a product called Drainzit Oil Draining System it really takes the mess out of it for me. My B&S drains right onto a frame part - and now I can avoid it.


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RE: Home Generator- Connecting to the house

I connected my 6000W generator using the male plug as described. I read about turning off all of the circuits after the fact. I used a #6 extension cord with heavy duty plugs and connected it to an outlet served by two #2 hot wires and a neutral that connects to the circuit panel. The outlet has a sub panel with a 30 amp breaker for each leg. The two #2 hot leads that connect to the main panel each have 50 amp breakers. Both leads connect to the same side of the panel. The output voltage from the generator tested at 130 volts per leg.

I failed to turn off my forced air LP gas furnace and my LP gas, on demand, hot water heater when I powered up the sytem. Both are powered by 120v. My furnace immediately started making a rattling sound and sending out smoke that smelled like insulation burning. Fortunately I had all of my other electronic equipment unplugged. It appears that the circuit boards in both units are fried. The manufacturer of the hot water heater said that the circuit board is designed to handle a surge of 240V.

Is it possible that the two 130V legs from the generator feeding into the main panel doubled the voltage to 260V?


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RE: Home Generator- Connecting to the house

Portable generators offer an excellent solution for emergency power backup for home, jobsite commercial backup, or recreational camping power. Heavier portable generators typically include a wheel kit for easy mobility
http://www.generatordepot.us/power-generators/portable-generators.aspx

Diesel generators provide an excellent solution for heavy duty use. Like any diesel engine, these diesel generators will be higher priced than the gas equivalent. But engine life and performance is higher

http://www.generatordepot.us/power-generators/diesel-generator.aspx

Here is a link that might be useful: power generator


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