gardenman said:
I've read through the post replies to Steve's original query asking if the generator breakers would trip if connected to the street and it doesn't seem like its been answered. It seems to me he has a valid point - aside from the legalities of the whole idea. Its certainly not a good idea but it does seem like the generator breaker of say a 5KW generator would easily trip trying to power your house and 5 or 6 or you neighbors - never mind back feeding the transformer. It seems it would pop the instant you power on. We all agree on the legalities, this is a technical question.
Technical??? How technical do we really want to get??? Do we really want to get into a long diatribe of technical terms like "Inductive Reactance" and on and on???
"In a perfect world" in theory...yeah maybe the breaker on the generator will trip. Maybe it will 9 out of 10 times... But all it takes is the 10th..."How perfect" is the world we live in today (think of this as you read this) and then think of the last time the power went out for whatever reason. Wasn't exactly a perfect world then was it???
Have you ever tried to run a LARGE motor off your generator??? Say a compressor etc??? What happens "more often than not"???
The motor just sits there and hums...but does the breaker 'pop'???
Take the large motor loads out of your home and you would be surprised what the current draw is. The average home, the majority of the time only draws an amp or two "at rest". At 2 AM how many lights are on at your house???
So far alot of hypotheticals...if you have ever seen "brown power" (I have during a power failure...more than likely a 'neighborhood generator' is the culprit) fairly good chance someone has a 'bogart connection'....
As far as "backfeeding" a transformer??? Hell you could backfeed 2,3, or 10 of them! Keep in mind (aside from 'minimal losses' inside a transformer) a transformer is not a "load"...it's just a really big (electro)magnet.
Now I (being an electrician) should be able to quote "exact numbers"...but I (like BB) don't really care too much about the numbers, sticking your fingers in a light socket isn't good. Any shock isn't good. It only takes a threshold of 5 milliamps to be fatal....regardless of voltage.
If your generator is "pushing the primary side" it can be lethal for those working on "supposedly dead lines"...
Electricity doesn't "follow any rules" in all reality. If you give it a path...it goes where it wants.
During a storm when all the wires out in the street "are turned into spaghetti" weird things can start happening. I've personally seen my fair shair of "weird s^it" happen when it comes to electricity. I've seen gas meters blown off the wall, holes blown through 1/8 plate steel, fires, welded breakers that have been 'hit by 13-8(13,800volts)'...ahh hell, just take my word for it.
If you want to have a "quick un-expected bowel movement" watch a main breaker hit by 13-8 try to get reset...only to find out the busbars inside the panel have been 'welded to the grounded case'...It not a pleasant experience, between the flash the smoke and the fact you aren't going home at 5PM can ruin your day.
Now imagine your a lineman working in an ice storm on a supposedly "dead line". You've been up for 36 hours dead tired freezing your a^s off and you and crew have many hours of work ahead of yourselves...people are waiting for you to "get the job DONE" and then it happens...Everything "falls into place" you let your guard down for just a second, some idiot has there generator backfeeding the primary, a ground is disconnected, a neautral is open the primary fuses are coordinated just right...ZAP
!!
Maybe it's not the full 7,800 volts...maybe it's just enough to make a 'reactance charge on the line'...If your lucky it's just been a good 'wake up call'...maybe just a small 3rd degree burn or a hole in the flesh...Maybe your wife just became a widow.
Is it really worth "F^%&ing;around with someone's life????"
The next time the weather isn't so great...the lights are going out left and right and it's "Just one of those days" where you would rather be comfy cozy sitting around the fire enjoying your favorite beverage...just remember there are men and women out there doing a "miserable job on days like this" that can't afford "mistakes"...Stop and take a minute out of your day and watch them work...then ask yourself "Would I really want to be doing that????"
Those folks...are called "Linemen".