I have an idea to install a standby generator and back feed the main house through a sub panel in a remote location. I’ve worked out the switching so it’s impossible to heat up PG&E’s line when the generator is operating, however, when the generator is not operating the load side wire will always be hot. Is that a problem, having the generator sitting there with a live wire to it’s load side? I don’t imagine it would be but if anyone out there knows for sure, it’d be nice to know. Thanks.
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You need a real transfer switch. Anything else is foolish.
I know about transfer switches but they appear to do only one thing and I can't get there from there, if you know what I mean. I just sent a schematic to one of the smartest electrical engineers I know so some good input ought to result.
I'm with gfretwell on this one. I picked up a manual transfer switch after Y2K for less than $50. Works great, it's safe, and was easy to install. And it solves your problem of permanently hot conductors outside at the generator. I see an accident waiting to happen.The automatic ones get pricey, but for my purposes the manual one is fine.Scott.
I'll post a schematic of what I'm trying to accomplish. Essentially, my on/off switches perform the same function as a transfer switch, but not quite. This is all doable and failsafe from a back feeding PG&E perspective. The switches are manual on account of cost and I couldn't figure out a way to do this automatically. The only problem I see is that the line out of the generator will be heated up when it's not in use.
It would be great to know what happens to the generator with the line that normally carries the load is hot despite the fact that the generator is off. I can imagine an issue or two but would like some input from someone who knows what's happening in there.
I'm sure my engineer buddy will know but in the meantime if anyone here understands the mechanics of this thing it'd be great to hear from them.
check this out
http://www.generlink.com/about_generlink.cfm
Interesting link Mike. This appears to be the same as a manual transfer switch. From what I understand a typical portable generator doesn't provide enough power to meet my needs though. That's why I'm going the standby generator route. I'm hoping to get by with a 10 kvw outfit but I haven't sized it yet.
sunsen,You can buy a 100 amp CutlerHammer manual switch for $260. Would not need the two subpanels and extra wire. Probably cheaper. Much safer!http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=42162KK
I think what I'm attempting to do is a little unusual. I'm not sure how a straight transfer switch would make it work. Looks like a pretty good price on that thing though for what it is.
Hre are some ideas for you, assuming you know what you are doing. Otherwise pay attention to the advocates of consumer safety <G>
My gen is a couple hundred ft from the house, no easy or low line drop way for conventional stby switch.
Manual start (12kW gen on 1300cc 1966 datsun engine, 1966 Chrysler speed control for frequency regulation)
Lock on main breaker panel at the service, need the key from that to start generator. (e.g. old car ignition switchs keyed alike, main breaker key location cannot be turned to get the key out unless breaker off to lockout main panel breaker )
Generator has an old 3m prong stove 50 A plug that plugs into where the 5 HP compressor usually is plugged into, so manual transfer there.
Gen start battery on trickle charge, 12V lighting system in the barn there to see to do the manual xfer incase of power outage.
Hope that gives you some ideas.
Per your OP, the genset tied to the line, not running, with pg&e power on, will be like locked rotor current (will trip some breaker), just one side of line connected for 240 Vac is ok except you should label it as such.
Manual xfer OK for me, only once every few year need to mess with it.
"locked rotor current". That's what I was wondering about. Thanks for the ideas.
Junkhound,
You would do well to employ proven and commonly used components wired in conventional ways that will be familiar to those operating and servicing the equipment.
I'm making an exception for you. But your place (and not just the electrical) must be so wacked out that it will all have to be recycled and razed when you die! No one else will be able to keep it going. (G)
Regards,
Jim x 3
No one else will be able to keep it going
DW says that sometimes also <G> , says if I die first she's agona' move.
Theres gotta be a few others like me out there though, let them choose and experiment ......
One of these days, when it starts raining again all day, I'll take some pix and post some details of my GSHP setup, NOTHING standard except the txv and compressor.
LOL, ain't that the truth. Lord help those in the will.....
I was going to say what coonass said. Looks like a beefy setup. If you're forking out for a 10kw genset and two subpanels I think you should seriously consider a manual switch.What's that transformer for? I don't see any primary service wire anywhere.Scott.
One problem is that he has never explained the layout.Reading between the lines I am guessing that the everything is existing except the generator and switches/relays.That the location of the 2nd sub and the PROPOSALED generator is 125 ft from the main panel/first sub.And doubling guessing that the guest house is some distance from both locations and that a stepup/stepodown transformers or used to reduce transmission losses.But no clue at all way the generator in that location. If was back in the area of the main/sub panel standard transfer switches could be used and simple and safe.And it is not clear if there are any critical loads at the 2nd sub panel or not. If not then main should be changed to directly feed the 2nd sub.If there are then you can still have a relay to kill the feed the guest house and have it operated off an aux contact on the transfer switch..
William the Geezer, the sequel to Billy the Kid - Shoe
I can't figure out where the primary is; Or the meter base.
The meter base is at the pole, 300' from the main panel. I ran conductors underground to the location of the main panel.
The guest house will be 1000' beyond the second 125 amp subpanel.
The generator is located where it is because that's where the propane tank will be and I have a good location for hiding the generator, (not to mention the noise issue). There isn't a tolerable location near the main house, otherwise I'd just put it there, use an automatic transfer switch, and be done with it.
The reason for the subpanel near the main panel is solely to isolate the circuits I'd like to power with the generator. The second subpanel will service the well pumps, which are fairly critical, and the transformer. I'm figuring the generator won't have to power the step up transformer, hence the relay to kill power.
Basically, I'm trying to figure out a way to locate the generator where it is, limit it's load and not have to pull any more wires than absolutely necessary. Also, it has to be fool proof when it comes to not back feeding PG&E. The arrangement I've drawn seems like it will work, with the exception of the line to the generator being hot all the time. How to solve that eludes me.
Ok, my assumptions are correct.Now explain in detail, or even better draw out a correct diagram that shows what each switch and relay are, ie, how many pole, how many throws, what is the control for the relay, etc..
William the Geezer, the sequel to Billy the Kid - Shoe
I'm not sure how to represent the switches other than to say one direction connects a line while the other direction disconnects the line and connects the wires to the starter on the generator. One switch would be down by the main breaker, as drawn and one, (the maintenance switch, so to speak), would be up by the generator, 160' away from the first switch. Is that two pole or four pole, with four contact points?
My thinking is the relay would stay closed as long as PG&E's power was on and open, disonnecting the line when power goes off and the generator kicks in. It would hooked up to the generator and do the disconnect at the transformer.
Bill is correct in that your system block diagram doesn't provide enough info for any of us to answer your question(s). More detail is needed.
For example, relays can fail - your system needs to be safe even when they do - and I can't tell from the block diagram whether that will be the case or not.
You would do well to employ proven and commonly used components wired in conventional ways that will be familiar to those operating and servicing the equipment. Energized wiring in a shutdown generator is not conventional.
And if you don't know how to represent the switches and provide a wiring diagram - and you didn't see the need to provide one with your original question - then maybe you need someone else to engineer this system (or to 'help' you do it).
Don't get me wrong, I hate to be singing this song - I'm all for DIY as long as you don't DIE, or worse, KILL.
Jim x 3
I actually met the guy who invented it at a show in orlando two weeks ago. he also manufactures them along with the meter that is on your house. it is actually automatic and I'm not sure why it would work with a 10kw generator. not sure if it's on the web site but the brochure I've got tells you how much everything in your home needs to run.
Please forget your idea before someone gets hurt or killed.
Are you planning to run the genset on a schedule for maintainence and upkeep?
Gonna have to disconnect the house then.
IMHO this is the least you need: Second item down here.
This is what you should have.
This is the piece de resistance, but ya gotta get two.
SamT
Yes, that's what the switch at the generator is for. When you throw the switch to turn on the generator for upkeep it disconnects the line. Seems like that ought to work. The only issue I can easily discern is that when the switch is "off" from the generator startup point of view the line is hot.
Couple of things bother me.
Standby generators do just that, standby and then start automatically when there is a power failure. Control panel handles all the logic and the switching.
Emergency generators are supposed to use manual switches.
You show two switches that can both start the generator. Unless they are wired in series there should only be one.
And having an isolating relay is a bad thing. In my world, relays/contactors fail all the time.
Without an actuall wiring diagram, no one can say if it will meet code/ be safe.
I can't think of a way to do what I'm attempting to do automatically. So manual will have to do. I don't have a problem with that actually.
Why not two switches that can start the generator from different locations? Seems reasonable to me.
How would you handle isolating the transfomer? Manually? I think that might introduce the human error factor into the equation. Is there a better way to do it automically?