There's been so much talk lately about back feeding with a generator and electrocution which sometimes happens down stream on the main power line. Why would anyone back feed their home or homestead with a generator of any sort without first disconnecting the main power, meaning isolating their home or homestead from the public grid??? IF you don't you risk destroying your generator if and when the main/public power comes back on since your generator and the main power would not be in phase with each other let alone killing some one working on the main lines...
- Thread starter John B.
- Start date
Billy Shafer
Well-known Member
Most do it because they have heard others. Say they have been doing it for years.With no problems. Most common through the dryer plug.But when things go wrong that is when your trouble starts. I just repaired a 17KW genset that was backfed. Bill came to 3200.00 dollars.
Bob Bancroft
Well-known Member
- Location
- Aurora NY
You're asking a logical question. Remember that not everyone operates with logic.
Russ from MN
Well-known Member
- Location
- Bemidji MN
There are a lot of people that do things without thinking, and when the power is out and it's dark and cold is when it will happen.
old
Well-known Member
- Location
- Camdenton Missouri
Many people just flat out do not understand that they can back feed the system so they do things not knowing they can cause problems. Heard of more then one person who made a double male cord so they could go form a generator to the house just by plugging the cord into a wall out let
K Effective
Well-known Member
Okay, let's discuss this a little bit, since you have much more experience with generators than I do. Obviously, this situation happens, so I must be missing something. I am using the male term lineman universally here, yes I know there are many female utility workers, it's just less typing.
For argument sake, say my house averages 10 amps load at 240 volts. My 8000 watt generator would supply about 30 amps of 240 volt current via it's built-in 30 amp receptacle. IF I were to accidentally back feed the line with my generator, about 0.4 amps of current is available to loads back on the main line, at 12K volts backwards through the normal step-down transformer on the pole leading to my house. (20A@240V)
ASSUMING there are more than three houses on the line, all averaging the same 10 amps load as my house, I SHOULD very quickly trip the 30 amp breaker on my generator. IF that generator breaker welds itself shut, the 30 amp dryer breaker used to back feed the main box should also trip open (bi-metallic heats in both directions). Past that, I have a 200 amp main breaker, but I ASSUME the generator would fail internally long before that level would be reached (48000W)
The only way I can see a lineman being injured from a back feeding generator is IF I were to bring the generator online and back feed while he is in contact with the previously dead line, AND he has failed to ground the line or take protection from it.
IF I am the only house or there are fewer amps of draw on the main line,and my little generator is actually carrying the whole line by itself, both sides could be energized, but I would assume any lineman is taught to verify that first, or at the very least assume both are HOT. IF he is working the repair HOT, as often is the case, the live line he is attempting to reconnect the dead line to would pose a much greater threat, and he would be protected by his equipment from the high side, and thus from the dead side as well. Simply grounding the "dead" line would trip open any generators on it before he reconnected to the high side, right?
So, technically, any accident nearly has to be caused by the worker failing to treat the fallen line as hot. I hate to say it that way, as it lays the blame on those people who work so hard at being safe and keeping us powered for all our silly wants.
Now, as far as damage to the generators back-feeding the line when the main power is restored, that I can clearly see. Every generator we have at work uses sophisticated synchronizing systems before connecting to the grid, any little generator would be no match for the power of the grid once reconnected, and could not survive the slip of synch.
I have taken measures to make my generator a physical break-then-make system, to protect the generator AND any repair persons.
Thanks for listening, and let's discuss this.
For argument sake, say my house averages 10 amps load at 240 volts. My 8000 watt generator would supply about 30 amps of 240 volt current via it's built-in 30 amp receptacle. IF I were to accidentally back feed the line with my generator, about 0.4 amps of current is available to loads back on the main line, at 12K volts backwards through the normal step-down transformer on the pole leading to my house. (20A@240V)
ASSUMING there are more than three houses on the line, all averaging the same 10 amps load as my house, I SHOULD very quickly trip the 30 amp breaker on my generator. IF that generator breaker welds itself shut, the 30 amp dryer breaker used to back feed the main box should also trip open (bi-metallic heats in both directions). Past that, I have a 200 amp main breaker, but I ASSUME the generator would fail internally long before that level would be reached (48000W)
The only way I can see a lineman being injured from a back feeding generator is IF I were to bring the generator online and back feed while he is in contact with the previously dead line, AND he has failed to ground the line or take protection from it.
IF I am the only house or there are fewer amps of draw on the main line,and my little generator is actually carrying the whole line by itself, both sides could be energized, but I would assume any lineman is taught to verify that first, or at the very least assume both are HOT. IF he is working the repair HOT, as often is the case, the live line he is attempting to reconnect the dead line to would pose a much greater threat, and he would be protected by his equipment from the high side, and thus from the dead side as well. Simply grounding the "dead" line would trip open any generators on it before he reconnected to the high side, right?
So, technically, any accident nearly has to be caused by the worker failing to treat the fallen line as hot. I hate to say it that way, as it lays the blame on those people who work so hard at being safe and keeping us powered for all our silly wants.
Now, as far as damage to the generators back-feeding the line when the main power is restored, that I can clearly see. Every generator we have at work uses sophisticated synchronizing systems before connecting to the grid, any little generator would be no match for the power of the grid once reconnected, and could not survive the slip of synch.
I have taken measures to make my generator a physical break-then-make system, to protect the generator AND any repair persons.
Thanks for listening, and let's discuss this.
Steve A W
Member
- Location
- Northwest Indiana
Many are too cheap to do it right.
Then there's the attitude that "They can't
tell me how to operate my house"
Then there's the attitude that "They can't
tell me how to operate my house"
showcrop
Well-known Member
Not everyone wears seat belts
Not everyone cleans their chimney
Not everyone saves for retirement
Not everyone limits their intake of high cholesterol foods.
Not everyone gets their teeth cleaned regularly
Not everyone stops at stop signs
Not everyone has fire insurance..................................
buickanddeere
Well-known Member
Some people are cheap and have no consideration for others.
buickanddeere
Well-known Member
And there folks is a prime example of the problem.
K Effective
Well-known Member
Care to elaborate?
I said, my system is break before make. Cannot physically attach generator without opening main breaker: transfer switch.
What I cannot see is any small generator powering any portion of the neighborhood without tripping some fuse/breaker, or eating itself.
If the main is thrown to disconnected, how can anyone downline get hurt unless someone throws the main on? No, I don't have a transfer switch, I backfeed through my welder outlet. I'm sorry if that offends anyone, but I've looked at transfer switches and still fail to see how they are anything but a glorified way to insuring the main is disconnected. Beyond the fact that it's "not the right way to do it", is there anything that the transfer switch has that isn't the same as throwing the main outside of a lock out?
GOTTA LOVE IT Electrical or Legal questions draw everyone out of the woodwork, many are experts (or think they are lol) and after 15 years here I've seen all sorts of POTENTIAL LIFE THREATENING ANSWERS AND OPINIONS. Its ones own life and home at risk which is why I as a retired electrical engineer always recommend people to consult a trained competent professional electrician and the NEC versus anything posted here INCLUDING MY COMMENTS as I'm long retired and rusty on the latest codes, but I still try my best to give safe sound advice even if some have far different methods or opinions or I disagree with Billy Bob and Bubba, you know the types, they wired their garage while downing a case of beer and by golly it works so they are experts who know more then the NEC and professional electricians..........
John T
John T
Billy Shafer
Well-known Member
Breakers don't always open. So turning the main off means nothing. Get caught with what you have will cost you.
Billy Shafer
Well-known Member
I agree John. Most don't understand that Billy Bob and Bubba are wrong. They need to have people that are up on the latest codes do the work.
i AGREE WITH SAFETY first.. but I am also interested in the discussing of what a 3k or 4k gen can/would do if accidentally backfed.
Assuming there are other houses on this grid via the hv transformer...
first off.. the gen breaker would have to overload and either open of be defective.
second... the motor would have to overload, and chug down and die.... OR the windings would have to burn up on the generator.
I share a transformer with my neighbor, so any gen I put on line would immediately power up his house as well as back feed through the hv transformer, and then try to power up at least 10 mores house just on my road. There is no way a small gen would survive the load, or the gen breaker survive the load.
What are we missing??
Assuming there are other houses on this grid via the hv transformer...
first off.. the gen breaker would have to overload and either open of be defective.
second... the motor would have to overload, and chug down and die.... OR the windings would have to burn up on the generator.
I share a transformer with my neighbor, so any gen I put on line would immediately power up his house as well as back feed through the hv transformer, and then try to power up at least 10 mores house just on my road. There is no way a small gen would survive the load, or the gen breaker survive the load.
What are we missing??
K Effective
Well-known Member
So, the reason not to back-feed through existing circuits is because I cannot depend on the main breaker in my home panel actually opening when I open it. But I can always depend on a transfer switch to break the circuit. [b:e6d05bba83]That is a new idea I had not heard before.[/b:e6d05bba83]
Please, that is what I want, a clear, calm explanation of what I am missing. Don't take the time to call me Billy Bob or whatever, but provide no actual information. Don't just say I am a bad example. TEACH ME! I don't know what I don't know.
All of this still does not answer the original question- how can my tiny generator carry any amount of the grid for any length of time without tripping itself out or eating itself? And, how can a utility worker NOT verify the line dead before working it?
Thanks for any more constructive information.
As for transfer switches, mine is in it's own panel box about 16x24 inches, with a big handle on the outside that says: ON-OFF-GEN. Blade type contacts, so when it is moved, there is no physical way it cannot disconnect. It does not disconnect the neutral, just the two hot lines. With a main breaker, you cannot see what is going on inside of it and cannot positively verify a disconnect, though it probably disconnects 99.9 percent of the time. My transfer box cost about 800 dollars to have installed by an electrician (10 years ago), it is all manual.
Garry
If I pull the breaker it HAS to disconnected. No 2 ways about that. And, in 57 years of life, I have never seen a breaker that didn't open, if anything it's quite the opposite, they won't stay on. But, okay, lets say that possibility really is a concern, fine. What does a high dollar transfer switch do a blade type switch won't do? Not fer nuthin', but the last time I had a certified electrician help me here it cost me over a hundred dollars to have him tell the guy from the power company that he had installed an entrance and panel. Took literally 15 seconds of his time- OVER THE PHONE! And I got billed for an hour, his min charge. So I'm not crazy about hiring people with a bunch of letters after their name, no offense to John of anyone else intended. But I'd still like to know what, if anything, that transfer switch does that pulling the breaker won't do.
K Effective
Well-known Member
Well, according to a couple other posts, a rooftop A/C disconnect and irrigation pivot disconnects were fused closed by lightning.
But, apparently, a transfer switch cannot be, if damaged similarly. The lever could move but the damaged internals would stay connected to the dead main line and the loads do not power off of the generator, no chance for cross-connection, if I am understanding this correctly.
But, apparently, a transfer switch cannot be, if damaged similarly. The lever could move but the damaged internals would stay connected to the dead main line and the loads do not power off of the generator, no chance for cross-connection, if I am understanding this correctly.
"Backfeeding" is a gnat of an issue with a common recoil start generator of 8kw or less. As mentioned above, if linemen (or women) are doing their job right (aren't overtired or pushed to hurry), any downed sections are isolated first and an unknown line is tied to ground before working on it, which even if you are the only house on a line, would kill your gen power, one way or another. Besides, a small generator might keep up with your own house, especially when the furnace, fridge, deepfreeze and well pump are going, but it's going to either pop a breaker or choke down and die if your neighbor drops a bagel in a toaster while re-heating coffee in the microwave. When you start talking a 25kw or 50, or even bigger generator, there is considerable more leeway in the loads it can handle, or to not realize the neighbors are playing their Xbox on your whole farm genset because someone either forgot to turn off a main breaker (or disconnect switch), or wasn't thinking and seeing it off, turned it on. This is why code writers have done their utmost to eliminate the "stupid" factor.
In a perfect world, circuit breakers would always open when switched, and it's my experience (as a professional electrician for decades) that they normally fail "open", not closed, but I concede that there can always be an exception, so a visually and/or mechanically verifiable disconnecting means is the next best possible way to prevent unwanted outgoing or incoming power.
Next best? Yup. The absolute best way to prevent unwanted power coming into your property, or leaving it, is to not connect to the grid at all.
I've also seen manual transfer switches fail because the mechanism hadn't moved in years, and the blades would not close on the "Gen" side. I've worked on more than a couple automatic transfer switches that didn't work in an hour of need. Nothing is absolutely fool proof. To keep yourself and other safe often requires going an extra mile. It also helps to make sure the generator and related safety equipment you may need later, is working a few times each year when you don't need it. It's worth it for when you do.
In a perfect world, circuit breakers would always open when switched, and it's my experience (as a professional electrician for decades) that they normally fail "open", not closed, but I concede that there can always be an exception, so a visually and/or mechanically verifiable disconnecting means is the next best possible way to prevent unwanted outgoing or incoming power.
Next best? Yup. The absolute best way to prevent unwanted power coming into your property, or leaving it, is to not connect to the grid at all.
I've also seen manual transfer switches fail because the mechanism hadn't moved in years, and the blades would not close on the "Gen" side. I've worked on more than a couple automatic transfer switches that didn't work in an hour of need. Nothing is absolutely fool proof. To keep yourself and other safe often requires going an extra mile. It also helps to make sure the generator and related safety equipment you may need later, is working a few times each year when you don't need it. It's worth it for when you do.
Billy Shafer
Well-known Member
This is the way a transfer switch. On a power failure it will start the generator. When it sees normal voltage. It will disconnect the line side to
the load. It will then stop in the middle. Nothing connected. Then it will transfer down to generator side.When power returns it will go through the
timers and go through in reverse
When you have a manual double throw switch. Up is line side. Middle is load. Bottom is generator. So when you switch it. It will break the line
contact. Then you push the handle down to the generator side. Which connects the generator.
the load. It will then stop in the middle. Nothing connected. Then it will transfer down to generator side.When power returns it will go through the
timers and go through in reverse
When you have a manual double throw switch. Up is line side. Middle is load. Bottom is generator. So when you switch it. It will break the line
contact. Then you push the handle down to the generator side. Which connects the generator.
buickanddeere
Well-known Member
Like I said, you don't understand what you are doing and the risks involved.
buickanddeere
Well-known Member
Are you aware that the welder plug has two live lines and a ground, no neutral?
The switching HAS to be INTERLOCKED so that no matter how somebody monkeys around with the switching and breakers. There has to be no way to connect the generator with the untility power.
buickanddeere
Well-known Member
Just about everything. Billy Bob and Bubba don't have the electrical training and knowledge of theory. Professionals in the field keep trying to tell Billy Bob and Bubba how to properly make connections. However Billy Bob and Bubba have some cheap streaks, egos that nobody is going to tell them what to do and they don't understand the risk.
buickanddeere
Well-known Member
No every generator is little. Not every downed line is connected to other services down the road. Bubba can energize the line after the lineman has started to work on it. You don't work safely by setting a booby trap and expect everyone involved to find every hazard, every time.
buickanddeere
Well-known Member
Error likely situations . A lack of respect for linemen by putting them in harms way.
K Effective
Well-known Member
[b:18a286c765]THANK YOU![/b:18a286c765] Well Worn, you gave a very thought out, calm answer to our question, and in doing so, I think, agreed with Bret4207 and myself on one aspect, and proved us wrong on the more important information.
To summarize:
In [u:18a286c765]most [/u:18a286c765]cases, a 8kW or smaller generator could not withstand being tied to a neighborhood of any size and continue to produce power. Yes, there could be and apparently have been exceptions to this case. [b:18a286c765]Which, considering the consequence of the risk leads to the next truth:[/b:18a286c765]
The properly installed circuit transfer switch setup is BY FAR SAFER to use to connect my generator to my house and my house only.
I am considering an automatic, whole house generator as an improvement for our farm (not much heavy farm load), and will be certain it includes such a device. Until then, no more back feeding.
To summarize:
In [u:18a286c765]most [/u:18a286c765]cases, a 8kW or smaller generator could not withstand being tied to a neighborhood of any size and continue to produce power. Yes, there could be and apparently have been exceptions to this case. [b:18a286c765]Which, considering the consequence of the risk leads to the next truth:[/b:18a286c765]
The properly installed circuit transfer switch setup is BY FAR SAFER to use to connect my generator to my house and my house only.
I am considering an automatic, whole house generator as an improvement for our farm (not much heavy farm load), and will be certain it includes such a device. Until then, no more back feeding.
Billy Shafer
Well-known Member
When it comes time to buy a whole house unit. Stay away from Generac. Cheaply built,no support from the factory and costly to repair.
K Effective
Well-known Member
Thank you for the suggestion. Do you recommend any other brand? Professional design/installation would maybe help get it sized right for our place, but I prefer to do as much myself as possible...
KEffective: thanks. 
"Pulling the main breaker" in most modern panels is impossible without removing one or more screws that hold it in and then attempting to bend a pair of #3AWG copper, or #2AWG aluminum conductors in a 100A panel, and no, it isn't easy, or good for the connections. Service entrance wire that size isn't made to handle repeated bending. In a 200A panel, even if you get the main out, you just aren't gonna be able to put it back without grabbing that breaker on 'five sides' with the strength of a gorilla. And when the grid comes back on, you are fighting with wire that doesn't want to bend and is "live", even with the breaker "off". What do you do when one of those now live wires wiggle out of it's connection as you attempt to wrestle it back into place? This is a perfect example of things that work in theory but don't work in practice. Never, ever pull the main breaker.
The only time a main breaker is removed, is if it fails and your electrician does the work, safely. In 40 years, I've never replaced a home service main breaker without replacing the panel and service cable, and only once when the main breaker had failed (after getting rain water into it due to a poor seal on the meter top hub).
As a word of warning should "something go wrong" when Joe Sixpack insists on pulling a main breaker: not every meter base will cut power when the meter is pulled. Most services above 200A use CT's for metering, so pulling the meter DOES NOT cut the power beyond it. Some meter sockets have bypass mechanisms in them. NEVER assume that pulling a meter will kill a service. If you still have fuses, even the fuses marked "Main" may not cut all power in, or out. You still need a transfer switch to safely power your place with a generator.
For the record: I have 2 backup generators (always carry a spare), AND a UL listed transfer switch, because even being an electrician who could easily and safely power my own place all by itself without back-feeding any part of the grid, I want it both EASY and SAFE enough that my dog could work it without making sparks. Granted, he's a smart dog, but I also want it easy and safe enough that my wife, kids, or any other future tenant here could make it work when needed, and without putting anyone in danger of electrocution.
Right. However, a transfer switch is designed that when ordinarily and properly operated, no "hot" parts are exposed, and you could switch it 30 times a day without endangering yourself or anyone else.
"Pulling the main breaker" in most modern panels is impossible without removing one or more screws that hold it in and then attempting to bend a pair of #3AWG copper, or #2AWG aluminum conductors in a 100A panel, and no, it isn't easy, or good for the connections. Service entrance wire that size isn't made to handle repeated bending. In a 200A panel, even if you get the main out, you just aren't gonna be able to put it back without grabbing that breaker on 'five sides' with the strength of a gorilla. And when the grid comes back on, you are fighting with wire that doesn't want to bend and is "live", even with the breaker "off". What do you do when one of those now live wires wiggle out of it's connection as you attempt to wrestle it back into place? This is a perfect example of things that work in theory but don't work in practice. Never, ever pull the main breaker.
The only time a main breaker is removed, is if it fails and your electrician does the work, safely. In 40 years, I've never replaced a home service main breaker without replacing the panel and service cable, and only once when the main breaker had failed (after getting rain water into it due to a poor seal on the meter top hub).
As a word of warning should "something go wrong" when Joe Sixpack insists on pulling a main breaker: not every meter base will cut power when the meter is pulled. Most services above 200A use CT's for metering, so pulling the meter DOES NOT cut the power beyond it. Some meter sockets have bypass mechanisms in them. NEVER assume that pulling a meter will kill a service. If you still have fuses, even the fuses marked "Main" may not cut all power in, or out. You still need a transfer switch to safely power your place with a generator.
For the record: I have 2 backup generators (always carry a spare), AND a UL listed transfer switch, because even being an electrician who could easily and safely power my own place all by itself without back-feeding any part of the grid, I want it both EASY and SAFE enough that my dog could work it without making sparks. Granted, he's a smart dog, but I also want it easy and safe enough that my wife, kids, or any other future tenant here could make it work when needed, and without putting anyone in danger of electrocution.
This subject has been covered with several good coments. Here is a picture of a very simple, two pole double throw knife switch. Although this one is small the ones used for a generatoe transfer switch would be sized for the load. It must be sized for the size of the service NOT the size of the generator! = 200 amp service means a 200 amp transfer switch!
Now the explanation the switch is an either line or load and cannot be connected to both at the same time. Automatic transfer switches use a coil to do the mechanical part.
For 3 phase or if you want the neurtal switched you would use a three or four pole switch.
joe
DPDT Switch
Now the explanation the switch is an either line or load and cannot be connected to both at the same time. Automatic transfer switches use a coil to do the mechanical part.
For 3 phase or if you want the neurtal switched you would use a three or four pole switch.
joe
DPDT Switch
buickanddeere
Well-known Member
People have been told here several times but unfortunately they do not understand enough theory to comprehend.
The neutral is an insulated load current carrying conductor that is held to near earth potentional with one bond to earth at the utility stepdown transformer/service.
The ground system is a non insulated conductor which bonds anything connected to it to nearly earth electrical potential . That said , many ground systems lack enough ground rods or ground plates not buried deep enough.
Why so we run both a ground and a neutral along with the live line to the typical wall receptacle ? There has to be a reason.
buickanddeere
Well-known Member
No failsafe means of preventing a connection between the utility and the generator.
Bret, sorry I missed this.
The "neutral" is a "grounded conductor", meaning it is carrying current back to the ground (midpoint of a 240 single or 3 phase "Y") connected service. The "ground wire" does NOT carry current except in the event of a fault. In other words, if you disconnect the "neutral" in a live circuit, you can get one helluva shock if you become the ground path, because it now becomes "hot".
A generator may or may not have the "ground" and "neutral" tied together. By code, that "tie" needs to be at the service disconnecting means, and kept separate at all other points in the system, simply because there is the POTENTIAL for a difference in voltage between any given "neutral" and "ground" that could kill you.
Back feeding a generator to a welder plug, unless just a couple feet from the main panel disconnect, violates the ground/neutral safety, to say nothing of the other safety issues involved.
As another side note, if you don't ground the frame of your generator and tie the generator neutral to ground, you technically have a "floating" system in which either hot leg or neutral can be tied to ground, but only one at a time. Such a system is inherently safe as long as you only contact one conductor at a time. Worked on a 480 system at a gravel pit that was fully floating - that was interesting.
(quoted from post at 11:24:17 01/03/17) KEffective: thanks.
Right. However, a transfer switch is designed that when ordinarily and properly operated, no "hot" parts are exposed, and you could switch it 30 times a day without endangering yourself or anyone else.
"Pulling the main breaker" in most modern panels is impossible without removing one or more screws that hold it in and then attempting to bend a pair of #3AWG copper, or #2AWG aluminum conductors in a 100A panel, and no, it isn't easy, or good for the connections. Service entrance wire that size isn't made to handle repeated bending. In a 200A panel, even if you get the main out, you just aren't gonna be able to put it back without grabbing that breaker on 'five sides' with the strength of a gorilla. And when the grid comes back on, you are fighting with wire that doesn't want to bend and is "live", even with the breaker "off". What do you do when one of those now live wires wiggle out of it's connection as you attempt to wrestle it back into place? This is a perfect example of things that work in theory but don't work in practice. Never, ever pull the main breaker.
The only time a main breaker is removed, is if it fails and your electrician does the work, safely. In 40 years, I've never replaced a home service main breaker without replacing the panel and service cable, and only once when the main breaker had failed (after getting rain water into it due to a poor seal on the meter top hub).
As a word of warning should "something go wrong" when Joe Sixpack insists on pulling a main breaker: not every meter base will cut power when the meter is pulled. Most services above 200A use CT's for metering, so pulling the meter DOES NOT cut the power beyond it. Some meter sockets have bypass mechanisms in them. NEVER assume that pulling a meter will kill a service. If you still have fuses, even the fuses marked "Main" may not cut all power in, or out. You still need a transfer switch to safely power your place with a generator.
For the record: I have 2 backup generators (always carry a spare), AND a UL listed transfer switch, because even being an electrician who could easily and safely power my own place all by itself without back-feeding any part of the grid, I want it both EASY and SAFE enough that my dog could work it without making sparks. Granted, he's a smart dog, but I also want it easy and safe enough that my wife, kids, or any other future tenant here could make it work when needed, and without putting anyone in danger of electrocution.
Thank you for the well thought out, non-insulting answer. When finances allow, I will look into a manual transfer assy.
Again, thanks for the well reasoned, non-insulting explanation. I understood the neutral was meant to be load carrying and the ground not, but since in all applications I've seen both run to the same ground at the entrance, I couldn't quite get the specific difference...or something like that. What you said make sense.
So in my case with an interlock kit on my main breaker, if the generator has a floating neutral, does the generator frame need it's own ground, or is that grounding accomplished via the ground conductor in the 4 conductor cable between the genny and the service panel?
IF.... your gen and transfer switch is at the meter pole...... The neutral and ground are tied together there, and grounded via the ground wire at the pole and or ground rod..... and the process is simpler.
If your gen is near the house and the switch is on the breaker box... then.. the ground and neutral conductors are usually separated on two busses.
At least in my power grid of multigrounded neutral system. Every transformer pole must have a neutral ground and every meter box has a neutral ground. In fact now, every pole has a grounded neutral as has since the 70s and all other pole mounted utilities are supposed to bond to the ground as well .
buickanddeere
Well-known Member
When Bubba connects his floating neutral generator via a three prong welding receptacle. It doesn't go well for the 120V loads .
buickanddeere
Well-known Member
Good to go and safe as described .
If Bubba only connects the genny ground and not the neutral to the welder plug ground, yeah, the 120 can get really wonky, especially if he's actually pulling 240 off the generator. It can also get wonky if the system ground/neutral tie point is a significant distance from the welder plug.
Knew one guy (a Bubba wannabe) who killed the compressor in his fridge because he hooked the genny Hot wire to one leg of his welder outlet, and Neutral to the other from a cut off extension cord, splitting a floating 120 between both phases. At least he properly connected the ground...
I'm guessing the fridge was trying to run on about 80 volts. I had to explain why the lights were going from not quite bright to dim as it tried to cycle.[b:b8b3382084]Scott[/b:b8b3382084], to verify what buickanddeere said, yes a 4 wire (twistlock) plug and cord from the generator takes care of both providing a proper isolated neutral and bonding the generator frame to system ground.
A local electrical supply house has a Clint Eastwood quote on the wall behind the counter that is very apt, in a font size that can not be missed: [b:b8b3382084][color=red:b8b3382084]"A man has to know his limitations."[/color:b8b3382084][/b:b8b3382084] Unfortunately, the ones who should heed it most, don't get it.
(quoted from post at 23:37:58 01/04/17)If Bubba only connects the genny ground and not the neutral to the welder plug ground, yeah, the 120 can get really wonky, especially if he's actually pulling 240 off the generator. It can also get wonky if the system ground/neutral tie point is a significant distance from the welder plug.
Knew one guy (a Bubba wannabe) who killed the compressor in his fridge because he hooked the genny Hot wire to one leg of his welder outlet, and Neutral to the other from a cut off extension cord, splitting a floating 120 between both phases. At least he properly connected the ground...
[b:5c5aa46ff0]Scott[/b:5c5aa46ff0], to verify what buickanddeere said, yes a 4 wire (twistlock) plug and cord from the generator takes care of both providing a proper isolated neutral and bonding the generator frame to system ground.
A local electrical supply house has a Clint Eastwood quote on the wall behind the counter that is very apt, in a font size that can not be missed: [b:5c5aa46ff0][color=red:5c5aa46ff0]"A man has to know his limitations."[/color:5c5aa46ff0][/b:5c5aa46ff0] Unfortunately, the ones who should heed it most, don't get it.
So how do you ground a PTO genset? Can I go to the ground at the building, or does it have to tie back to the entrance panel ground?
buickanddeere
Well-known Member
Supposed to connect some sort of robust external ground lead between the building ground and the exterior chassis of the generator . A Welding ground clamp and cable works well. #6 extra flex cable is usually sufficient .
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