Now that we've been through Isabel, Floyd, Fran, and countless ice storms, the lack of power has started to wear on the "It's like camping indoors" thrill.
I have a utility shed outside the house with a subpanel, and was wondering if it was possible to set something up where a generator can power a few home circuits by attaching to the subpanel outside.
It would be impossible to attach the generator to the main panel in the house due to the location of the panel in a bedroom wall.
Bill, it's actually easier to connect to subpanels since you don't need to black out the entire place to do it.
Just get your local sparky to fit a manual transfer switch in the supply line to your subpanel and fit a plug/socket receptacle on the outside wall to connect the generator.
Some brands/types of sub-panels have "kits" that can: 1) Make the panal suitable as a "service" panel (basically, bonds the neutral to ground and makes it more difficult to remove the designated "main" breaker; and 2) can take TWO "main" breakers and also will mechanically permit only ONE "main" breaker to be ON at a time. IOW: the service panel would have a transfer switch built in!
The proper way is to use an "automatic" or "manual" transfer switch. You never want to run the risk of back feeding the utility. The transfer switch provides a mechanical interlock that forces the " Main" breaker open in order to close the "Generator" breaker. If you connect the generator, back feed your sub-panel to your "Main" panel, and forget to open the "Main" breaker, your going to energize the lines coming into your house. Your 120/240 volt generator will back feed to a tranformer that will step it up to a higher voltage (2400, 4160, etc...).
Your going to really piss off a utility lineman, who expects the circuit to be de-energized, if you don't kill him first.
It might just be me, but I believe the responders to this post missed a bit of information in the original post.
They way I read it he wants to power some circuits in his home by connecting a generator to a panel in an out building.
If he installs a transfer switch in the out building to connect the generator to the sub panel, the sub panel will be fed from the house, or the generator. The feeder between the house, and the out building, wont see any power from the generator.
Interesting delemma if he wants to feed some of the circuits in the house panel, and be isolated from the utility while the generator is running feeding the out building sub panel.
Louis--
********************************************* Remove the fish in address to respond
Hokay. If that is the case, he's pretty stuffed then - he would have to switch the utility point-of-entry from the house to the sub-panel, kind of defeating the purpose.
It would be better to connect the transfer switch up at house..
I think a lot of you understand my question, but the problem is that I'm not sure I understand the answer(s). So, here's my 'for instance' example.
Let's say the power in the neighborhood goes out... Can I go to the main panel inside my house, flip off the main coming in from the pole, turn off most of the useless breakers (recepticals, range, AC, etc) and then go out to my storage building to fire up my generator. The generator would be connected to the subpanel, and the power from the generator would have to backfeed through the line back to the main panel in the house and have it keep the fridge running so the milk and eggs don't spoil.
I hope this helps my clarify my original question...
That will work, until the first time you forget to trip the main. Then don't be surprised to find your service drop laying in the yard for a few months until a pissed off power company gets around to hooking it back up. (at a huge fee) In some states you might just see a cop. If a lineman gets hurt, count on seeing the cop.
By installing a shunt trip breaker that is retained by a service disconnect bracket and feeding the generator current through it into the sub panel, by using a service disconnect bracket on the breaker that supplies the outbuilding panel feeder, and by installing a shunt trip main breaker in the house panel you could install a reasonably safe system. But to make them both work you would have to run control wiring from the line side of each breaker to the shunt trip coil of the other breaker. The shunt trip coils would open the breaker at the other end of the circuit if power appears on the line side of the breaker were the control wiring is tapped on. The breaker retaining brackets are essential on any breaker that is not bolted into it's position that could receive power from the breaker terminals rather than from the buss to which the breaker's buss clips are connected.
It would be far simpler and much better practice to run the generator supply conductors to the house panel and tie them into a normal transfer arrangement. The only reason to use the shunt trip arrangement is if you have an existing raceway that is large enough for the feeder and control wires but not large enough for the feeder and generator supply wiring. If you are not fully familiar with the variety of service wiring arrangements, including split buss panels, multiple disconnect services, and dual meter energy conservation connections you will need to have the finished assembly checked by a master electrician to rule out the presence of sneak current pathways that can endanger outside wiremen.
Need a transfer switch or a physical and electrical means of disconnect. For your service.
Where are you going to ground this new electrical service? You will need 3 wires hot neutral AND ground if you just using 120v and your going to need 4 wires if your using 240v.
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Back feeds are illegal every where I have worked. I know your using terms that your confortable with but a back feed is a dangerous thing.
my clarify my original question...
If a lineman gets hurt, where I live your going to be in jail immediately. You will serve at least 2 years of the 5 year sentence.You will be disconnected from the utility and sued. Follow the rules and guide lines by your utility. Call the utility! Follow what they tell you to the letter and all will be safe and sound. If you worried about the cost then just run extension cords and forget the transfer scheme. Of course you will probably burn out the motor on the refer because of the voltage drop. But hey milk did not spoil.
While this scenairo, if correctly hooked up, would work, the origional poster didn't want to open up the wall with the panel. As you mentioned it would require additional wire, and I suspect that there isn't conduit from the outside to the house panel.
The part that would be unacceptable to me is the lack of mechanical seperation of the two voltage sources that a transfer switch would have. With the above configuration, a burned out trip coil could result in back feeding out to the utility. This is a perfect case for making the installation as stupid proof as possible. If it is physically possible to happen, at some point it will.
In my opinion the case he presents will require connecting to the house panel with a transfer switch to be correct, and safe.
Yeah, but I'm afraid you've stepped in it. In the US, the generator must have a positive interlock to prevent backfeeding into the supply (utility). Even if you connect the subpanel through a transfer switch so it can be supplied by either the utility (from your main), or from the generator,
*that* would only power your storage building. Not the main residence.
With your scheme, if you ever forgot to open the main feeder, you can kill a lineman. The fact that your wiring installation doesn't comply with NEC, you would be in courts for decades. Not to mention you may never get a lineman to wire up the service to your house again.
Several people have asked about this sort of thing recently (probably because of the 8/14 blackout followed by the power outages from Isabel). All the posters 'promise' to always open the main, or say something like, 'I would never forget to open the main.'
But the NEC has the requirement for a positive, mechanical interlock for a very simple reason. People have forgotten, and people have died.
What about if your spouse tries to light-off the generator because you're not home? Sell the house and the next guy kills someone and claims you signed something stating all the wiring was up to code??
Please, don't do it the way you're thinking of. Instead, if you *have* to power the fridge after the next major blackout (predicting in oh, say,
2027), get an ordinary, heavy-duty extension cord. Put the generator outside, run the extension cord in through an open window. Unplug the fridge from the house outlet and plug it into the extension cord. And be careful of carbon monoxide near the open window. Once the fridge is cool, unplug it and plug the next appliance into the extension cord.
Clumsy, I know. But considering how often the power is out for long hours, and the risks of DIY plans that can kill people......
Well, I guess a simple "no" would have worked ;), but thanks to all who responded, as I have learned quite a bit. As far as I am concerned, if it's not to code, I'm not doing it.
If, by chance, in the next ice storm or hurricane, a tree should fall on the house near where the main panel is located, I may take some extra time during repairs to work in a generator connection, but until then I'll spend $100 on a mini-fridge, stick it in the shed, and run it directly off the generator. Simple... yet effective....
The utility I worked for or any that I know would never rely on a customer supplied switch of any type to provide personnel protection for its linemen from an energy source. If a lineman that worked for me assumed that a conductor was dead without first testing and grounding it or handling it with hot line techniques, then he violated our safety practices. Any low voltage switches are not germane to a safety discussion. Whether they exist or not has no bearing on the personnel safety issue.
In my own case, I have a 5kW 120/240 volt gasoline powered generator. I connect it via an unused 240 volt electric dryer outlet and use it to power my full house. It was notably successful during Y2K. I switched my house load over to the generator at about 10:00 PM on New Years Eve, and the electric system did not crash as a result. For a small investment, I achieved a huge result. Regards,
Thanks John, I wondered how we all dodged that bullet.
BTW Scott McNeely was right W2K did cause more problems than Y2K. I just didn't know you were our savior. Be carefull with that suicide cord. We don't want to lose an asset like you.
Let me get this straight, you work for a utility (in fact it seems you have a supervisory position), yet you still believed all that Y2K stuff about the lights going out all over?? Considering all the time and effort spent on getting ready for Y2K, why would you not trust that it would be successful? Much less run a generator for 2 hours beforehand on the slim chance that your coworkers might have missed something?
Well, thanks for keeping the electric system up by using your generator, we all appreciated that ;-)
I assumed he was making a joke although I did have some inteesting conversations in the waning days of 1999 about the upcoming disaster. It seemed that the more "embedded" the computer was, the less people understood what it did. I didn't know a single person at IBM who really believed Y2K was anything but a marketing opportunity. Certainly there were plenty of "fixes" for billing programs and such but not much else. The most ridiculous were the folks who thought their car was going to die. I am still running a FAX program that is not Y2K aware. The only problem is, it sorts faxes post 2000 lower than 1999. About a week into January I archived all the 1999 and earlier FAXes into another instance of the program and got on with my life.
Yes. Our experience has been that the more 'embedded' software doesn't even care what day it is. It still had to be reviewed for any impact (can't talk managers out of anything sometimes ;-) The logging programs and 'interval' calculations sometimes at least had a time component so it was worth a 'look see'. But how many digital PID controllers care if the year is 99 or 00???
Considering that quite a bit of the electric system is still electro-mechanical and embedded software often is for a function that isn't date dependent (protective relaying schemes seldom care what time of day it is), I think the idea of the country going 'dark' just because a clock 'ticked' was pretty far-fetched in the first place.
Actually, I did purchase the generator well in advance with the expectation that it might be necessary for Y2K. If I was wrong and the generator saved my basement from flooding during an extended outage at any time, then it would pay for itself. This turned out to be the case.
I am a graduate electrical engineer and among other things, I was responsible for the design and installation of my company's power system control computer network. I was confident that the North American electric system would survive the time change given the modifications and testing that had taken place. Such was not the case in the undeveloped world. Since the new year would begin in Africa and Asia before the western hemisphere, I surmised that blackouts would begin there and as the world turned it might cause a panic in the US. August 8th demonstrated the fragility of the electric system. What I missed was that the systems in the undeveloped world were so unsophisticated and archaic that even though little mitigating action had been taken, it did not matter.
I do have though 2 Y2K shotguns that I have not gotten any productive use from.
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