Generator Test Revisited RANT ALERT

John T

Well-known Member
Since this could save a life, I thought it best and worthwhile it be revisited (I just copied and pasted). It concerns why "IN MY PROFESSIONAL OPINION" 4 conductor/cords and 3 Pole 4 Wire Grounding Plugs and Receptacles
(4 wires/terminals) should be used instead of say a welder or home appliance 3 wire Plug and Receptacle and only a 3 conductor cord BUT DO AS YALL PLEASE.


WARNING This is a long rant so DO NOT READ IT if you don't like that, but if you do then NO WHINING OR COMPLAINING, you have been forewarned!!!!

WOW, as typical when an electrical or legal question is asked it really draws out opinions, everybody comes crawling out of the woodwork, YES INCLUDING ME LOL, some lay some professional, some ignorant some educated, in my professional trained "opinion" some are right, some potentially hazardous and perhaps DEAD wrong!!!

Let me set forth some basics which may or may not be right or wrong, I'm NOT saying. However, they are based on my education (BSEE) and 40+ years as an Electrical Distribution Design Engineer (though long retired so no warranty remember) so take or leave them as you wish NO WARRANTY do whatever you please is fine by me. Consult local authority and the utility NOT me or anyone (especially lay opinions) here is my advice you can take or leave.

1) I'm talking about typical 120/240 VAC Single Phase Three Wire home distribution and emergency generators here.

2) This applies to the number of poles and connectors if you're using plug and receptacles as well as transfer switches as discussed below.

3)If you want to use only a TWO POLE Transfer switch (sort of the same effect if you just use a cord for the transfer), YOU DO NOT SWITCH THE NEUTRAL just the two UnGrounded Hot Phase Conductors. The Utility Grounded Conductor (Neutral) and the Gensets Neutral are bonded together. The incoming Utility Grounded Conductor (Neutral) is of course still earth grounded none of that is changed. In this configuration, the genset IS NOT considered as a "Separately Derived Source". In this configuration the Genets Neutral IS NOT TO BE TIED TO ITS CASE FRAME and if it exists that way that tie should be severed.

4) IMPORTANT NOTE: In the configuration above where you DO NOT switch the Neutrals (they tie together) and the genset is NOT a "Separately Derived Source" and you are transferring 120/240 volt Single Phase Three Wire and you use a cord, YOU NEED A 3 POLE 4 WIRE GROUNDING PLUG AND RECEPTACLE (i.e. 4 terminals 4 wires) AND OF COURSE A 4 CONDUCTOR CORD

NOTTTTTTTTTTTTTTTTTTTTTTTTTTTTT

only a 3 wire (3 terminals 3 wires). A typical 240 volt (only) appliance plug and receptacle (2 pole 3 wire grounding) for a load that's 240 ONLY (no 120) DOES NOT SUFFICE AND COULD PRESENT A HAZARD but if you want to do it that way its your life, your home, your risk so do as you wish !!!!!!!!

5) Now, as to how and why it can be hazardous to NOT use the sufficient number of conductors/terminals/poles (3 when 4 are required) has to do with the potential hazards of mixing, matching, and substituting Equipment GroundING Conductors for the Neutral Grounded Conductor. NOTE I've tried here for years to educate the Billy Bobs out there why that's hazardous but I give up, they cant and never will understand it, but that's not anything bad against them, its just that you cant take what requires years of study and experience and volumes of books and describe it here in a paragraph. HOWEVER DO NOTTTTTTTT TAKE MY WORD FOR IT, STUDY THE NEC AND WHAT THE TRUE EXPERTS SAY AND MAYBE YOU WILL SEE WHY IT CAN BE HAZARDOUS.

6) TO THOSE WHO DID IT THAT WAY FOR YEARS AND NEVER HAD A PROBLEM. That's fine do as you wish, I'm NOT telling you to do it otherwise. HOWEVER just because it WORKS does NOT mean its the safest way and NOT potentially hazardous. You may possibly perhaps just want to stop and think that maybe just maybe the EXPERTS like the panel who write the NEC, who are trained and experienced professionals and know 1000 times more then you or I about electrical safety and hazards JUST MAYBE THEY KNOW MORE THEN YOU AND BILLY BOB!!!

HOWEVER ITS YOUR LIFE, YOUR HOME, YOUR FAMILY AT RISK NOT ME, SO DO AS YOU PLEASE AND IGNORE THE TRUE EXPERTS IF THEY SAY ITS HAZARDOUS BUT YOU THINK YOU KNOW MORE THEN THEM!!!!!!!!! If your doctor says you need heart surgery or will die and its hazardous if you don't, do you take their advice or Billy Bobs or a Tractor Forum LOL

7) Finally to those who worry, or those who do NOT worry about a genset backfeeding the utility and possibly causing death, IT HAS HAPPENED ITS POSSIBLE GIVEN CERTAIN CIRCUMSTANCES. However, trained professional linemen and NOT STUPID so its rare it ever happens anymore BUT IT STILL COULD. A close friend is a Journeyman lineman (and I worked with many many of them for years when I practiced) and they can see if theres lights on in a home and they can hear a genset running BUT JUST IN CASE TO PROTECT THEMSELVES THEY DISCONNECT OR GROUND LINES to prevent such a problem. SO, ITS RARE IT COULD HAPPEN but why take a chance when a life is at stake.

CONCLUSION for 120/240 Volt Single Phase Three Wire emergency genset distribution, do as you please and use 3 wires (even where 4 is safest per the NEC and Utility Company and Experts) and as you wish and ignore whats safest and the NEC says AT YOUR OWN PERIL as you like or if ITS ALWAYS WORKED BEFORE BY GOLLY LOL. Its your home your life at risk and maybe the finest experts in the world dont know as much as your or your brother in law or Billy Bob say. BUT MAYBE THEY ARE RIGHT AND YOURE WRONG HMMMMMMMM WANT TO BET YOUR LIFE ON THAT!!!!!!!!!!!!!!!! FEEL FREE

Im here to help NOT fight or argue so yall do as you wish or whats worked for years and what you think is best regardless if experts say otherwise if you're convinced you know more then them, no sweat off me, its NOT my home or familys life at risk....... Again DO NOT take my advice it may be wrong it may be right, but if you do want to take the advice of EXPERTS regarding life threatening situations, consult local utility providers and/or the NEC instead of non trained non profession non expert lay opinions even if their way always worked no problems!! Your life your choice

God Bless, keep safe, best wishes

John T
 
John T - what I know about electrical stuff would fit in a thimble, so your post is way above my head.

I do know I have enjoyed you're posts and find them informative and well written. Keep posting.
 
Having spent a lot of time last summer trying to track down the source of stray voltage on an earth ground at the barn. I will put in my view that " The only way to tie in a generator is to completely isolate the generator from the Power lines with a switch that breaks ALL incoming wires". A faulty appliance or a bad connection can cause a back feed to occur leading to energizing of the power lines and thus causing injury and or DEATH to occur to a Lineman performing repairs.! It would be much better to be hot or cold for a time than to know that my actions caused someones injury or Death. I will never again hook a generator through a back fed breaker in my switch box.
 
Good Post, NO Problem, if you want choose a 3 Pole Transfer Switch (switch both UnGrounDED Hot Phase Conductors PLUS the Neutral Grounded Conductor) that's ALSO code compliant but remember then Genset must be configured as a "Separately Derived Source",,,,,,,,Its Neutral must be bonded to a "Grounding Electrode"

Fun chattin with ya, keep safe

John T
 
Thanks for the kind words, hey I try me best (although it gets frustrating at times lol), I also enjoy your posts......

John T
 
John T, I have an example I'd like to get your opinion on. The line that brings electric down the road I live on has 7,200 on the top wire and the bottom is the ground. It's the same system that was put in in 1948 here. Each pole has a copper ground wire down the side of the pole and goes to the bottom of the wood pole in the earth.

Over the years in ice storms I've seen that bottom line break between poles and fall. The Hot line(7,200) was still connected and we still had power. In fact I've seen that condition like that for as much as 6 days before the power company got around to making the repair. And the power stayed on for all the houses down this road till the repair was made.

What if any type of danger were the houses/people in under this condition?

I have my generator wired with a mechanical interlock from a dedicated breaker (for generator) that is back fed, to the main breaker. "can't turn generator breaker on unless main is off and main can't be turned on while generator breaker is on"
It's legal here to operate with this setup.

Do you see potential problems with this setup?
 
John I have a gen set that has only a three prong on the 110 side and only a three prong on the 220 side. How do you use a four wire set up on that? A picture would work better then words because I don"t under stand half of what is printed. LOL thanks.

Bob
 
John, if you remember, I had considered an installation off my miller trailblazer, an NT 251 Welder, 8500 watts continuous, back fed through a 3 wire conductor, a 50 amp wire size if that is correct, maybe (3) #4, aluminum. The one thing that I never forgot from that discussion is that the neutral needs to be bonded at the panel, and not "downstream" whereas you mentioned it may be common to for gen sets to have the neutral bonded, whereas you said to simply disconnect that conductor, so the above is true. We discussed switching for something like this and I believe you suggested the type and it should interrupt or isolate the feeders coming in, so that when that backfed line is energized, there is NO possibility of any backfeed to the incoming service, secondary lines, subsequently to a transformer and thus much higher voltage energizing the primaries, hence the safety concern to the linemen.

Well, I may have followed through with a safe code compliant installation utilizing that Miller welder, but it was decided to go with a solar/battery back up power, with all the appropriate accoutrements, code compliant and SAFE, with the capability to tie in that Miller welder safely to bulk or trickle charge the batteries when solar is off or its cloudy.

It is illegal, against code or what have you, as I know when working on these things, doesn't it call for things being tagged out, so that the person at risk, KNOWS its locked out, tagged out, cannot be energized ? Without the proper switching, sure people know if you flip that main while back feeding your service, this will happen, and most won't ever do that, but what about the mistake, what about the one time it happens, because its possible, as its connected versus, a closed circuit, when it should be open while a genset is on.

I don't know what other safety protocol line(people) employ when repairing overhead and similar distribution to prevent an accident, but what line person can work comfortably, (and people want their power back on yesterday) under emergency, inclement or dangerous weather, to restore power, with this scenario of someone not wanting to properly/safely install back up power equipment that meets the criteria to ELIMINATE any possibility of this SITUATION from ever happening, isn't that the point of all this NEC, code, and acceptable designs ?

I realize people will always say it works, and I'd never throw that switch, and in a dire emergency its going to happen, myself included if there was no other choice, that main would be tagged, taped off and the panel door secured at least, but that does not in any way make it RIGHT!

My experience is in commercial, low and high rise construction as well as correctional, health, educational and many mixed use high dollar construction projects, I know enough about power distribution to be dangerous, have been involved in high voltage 15KV and up splicing, all kinds of large building services, existing upgrades with temporary services built that would make your hair stand on end literally, have tied into the Con-Edison grid in NYC many times, and have encountered very dangerous situations, one thing I learned a long time ago, leave it to the expert designers, qualified electricians and those who are both experienced and properly trained, if you do not, you should NOT be surprised when the results don't turn out as expected.

I've been nailed by 220 and magnetized to a steel column, no it did not throw me off, it took 2 men to pull me off while they got nailed as well, its clear in my mind, I'd not be here today, instead my flesh would have kept burning, (still can see the 3 scars from those bare wires) and I'd have kept writhing from electricity passing through my body, its a miracle I did not die as both arms were locked onto that column, heart did not short out or whatever the heck happens to you, it felt like I was in the electric chair, and you want to know why, because some ignorant @ss$ole left a cover off an old thermostat, back when unit heaters were wired that way, with full voltage, thank god it was not the 440 to the big compressor we had. All it takes is one dumb ignorant move and you could get burned, fried, arc'ed or and or killed, I don't understand why people fool with this stuff, I know what it feels like, and know that it happened by pure ignorance, just walk away from bare wires, under a small shelf, where a person will reach someday, and walla ! When I think back, had I been alone, what an awful way to die, truly awful, flesh burning, you cannot move and you cannot do anything about it except take it,

Folks, don't be ignorant when it comes to electricity and safety, please !!!

John, I always applaud your detailed efforts to comment here on this forum, and the time you take to do it, no I'm not putting you up on a pedestal, that would be wrong, just saying, I personally appreciate the time you take to post and the good faith effort you make here, along with everyone else on this forum included, for the sole purpose of helping others ! In your case its always in regards electrical and legal issues, concluded of course, with the typical "John T Disclaimer", which I enjoy the most !!!! LOL !!!!
 
We have friends that have a large solar system, I think he said it's 6.5 KW. They are on the grid and sell power back to the utility on sunny days. There must be some safety interlock to prevent back feeding during a grid outage on a sunny day?
 
I understand your concerns since I was an electrician for over 40 years and still a state licensed journeyman card holder in Texas. Most of the really dangerous installations I have seen were on farms and rural property because rural folks tend to do so much for themselves....this included gensets and other circuits. The basic fact is that nobody without proper training should do ANY electrical work, period. Hire a pro.
 
We farmer types tend to deal with a lot of govt regulations that come from fellas sitting behind a desk and don't know what they are actually regulating down at the farm.

We end up having to skirt those govt types and just get disenchanted with the whole govt regulatory thing.

On the tiny bit of wiring I've ever done, I came to the code stuff with the same attitude. Oh, just more beauracrats sitting around making stupid rules, how do I get around their junk....

After playing with the little bit of wiring, I came to find out the electric code, anyhow most of it, is really there to help, one of the few govt things that makes some sense.

Took a while to adjust my attitude on that, from regular govt stuff.......

I think maybe some of the redneck attitudes towards the code might come from that same background?

Paul
 
I've even heard about these posts in the basement, LOL.
As I said there, as long there are people, there will be Darwin Award Winners.....
 
Just google search " how often are lineman killed by backfeed" . Apparently it is often enough for me to get a weekly fatality story in a brochure attached to my weekly paycheck at one company I worked for. There are still fatalities weekly. Several weeks back two journeymen I know where sent to a job at a sewerage treatment plant in the high voltage yard. The "out of towner" foreman said " since you guys don't know what you are doing ,I will split you up to work with the two guys that have been here . The one guy gets in the lift basket with "experienced guy". They point : this side of the yard Hot --this side dead. Goes up in basket with hot stick and 2 foot pole . Nobody that knows what they are doing has a 2 foot extension on a hot stick. Hits " dead " bus with lift bursts into flames [ him --his body] as bus is hot and all four tires blow out large flash blinds guy on ground. Pavement catches on fire . Truck is locked .Window gets smashed to get extinguisher, 911 tells guy to spray some water on him. Fire dept comes [20 minutes later] .They say we are not electricians and you go up and get the guy out of the lift. Now other lift has to take two more perfectly yet uninjured guys up next to lift and hot bus to pull [still burning] guy from one lift to the next. Without shaking lift into hot bus. A few days later guy [who was concious the whole time ] dies from burns.
To me the mistake is the guy assumed the bus was shut off for work as indicated by his intention to do a half -assed hot stick test. He had no idea that bus was hot. Only one man should have been in lift for test ,another mistake.
 
I had an electrician set up wiring for my PTO generator. There"s a plate that he installed in the main panel that only lets the switch from the power company or the switch from the generator be on (one or the other). He said it was a code and / or power company requirement to prevent feeding power from the generator back into the power company grid.
 
Good info although its quite sad, goes to show the danger exists but you and I already knew that.

Thanks dr I like to read and learn from your inputs as Im pretty rusty on current code HOWEVER I remember safety and the basics

John T
 
I don't view the National Fire Protection Assn (NFPA) nor the NEC panel as your typical fat cat bumbling federal bureaucrats. They are true experts (NOT Government workers but professionals in the electrical field) and the finest minds in the business who have worked, learned and dedicated their lives to electrical safety and some changes in the code are because of a fire or a life was lost so its investigated and improved.

How do I know this?? Its because in my day I have attended their seminars and workshops, I have talked to them, I have read their treatises. It was in the day of the likes of Joe McPartland and Mike Holt etc who are NOT Bureaucrats but electrical contractors and educators.

So again I say to Billy Bob and Bubba (NOT you) if they have a method they know is safer and better then the NEC says and they are willing to bet their life on it GO FOR IT

Thanks for your input

John T
 
Thanks for the kind words. Hey Im glad youre not putting me on a pedestal cuz I will come tumbling down and hard lol

Like all mortals Im often wrong but when a guy spends his life learning and practicing in a particular field I just try to impress on the Billy Bobs out there to just consider the possibility that person may know whats safer then an untrained inexperienced non professional, so I try my best to offer advice which may save someones life and then let them do as they please it go BUT IT GETS FRUSTRATING LOL so I have to rant at times, thanks for listening

Usual disclaimer......

John T
 
Yo Bob, hows come youre not at Iola with the brother in law?????? I bet they are bad mouthing you this very moment??? Coming to Florida in 2015???

If you use cord and plug connected tools that are plugged into on board mounted genset receptacles you don't need anything else nor does the genset require an external grounding electrode (ground rod). It does have its Neutral bonded to the frame ya know

HOWEVER if that genset is 120/240 and if you want to use it to power your home (NOT as a Separately Derived Source), you would have to mount/attach/wire a 4 prong (3 pole 4 wire grounding) receptacle,,,,,,,,,,,,,, isolate out the 2 hots (ones that are 240) and Neutral,,,,,,,,,,,cut any frame chassis bond wire to Neutral (prob how its currently wired up),,,,,,,,,,,wire up 4 wires and a 4 wire cord as the 2 hots, the Neutral, and a new wire to the frame/chassis as equipment Ground.

Run it to your panel (with perhaps a lock out type of branch circuit breaker used to backfeed the panel or better a true transfer switch),,,,,,,,2 hots to the 2 pole backfeed breaker,,,,,,,,tie genny Neutral to panel Neutral and ground to panel ground

Im not smart enough to draw and post that as a picture

John T
 
What if any type of danger were the houses/people in under this condition?

Its done often after a wind storm as earth serves as the current return and you still have some service at least. Id have to stop and think to analyze all the dangers SO NO WARRANTY IM TALKIN OFF THE TOP OF MY OLD HEAD NOW LOL, there are indeed stray current paths along the surface of or down deeper into earth so especially on wet earth your body could get in parallel with such a current path and given the right set of wrong circumstances some current may find a path through your ticker and it only takes like 30 to 50 milliamps to make it de fibrillate I think



"I have my generator wired with a mechanical interlock from a dedicated breaker (for generator) that is back fed, to the main breaker. "can't turn generator breaker on unless main is off and main can't be turned on while generator breaker is on"

It's legal here to operate with this setup.

Do you see potential problems with this setup?

NOPE as long as the interlock mechanism is in place you cant backfeed the utility......

John T
 
John just how much stock do you own in copper wire. In the olden days we had two wires hot and neutral and a plug that could be put in either way so sometimes the case was hot and then turn the plug and the case is grounded. So we made plugs that would only go in one way then the case would never be hot. I grew up using these old systems and yes you could get a pretty good shock if the plug was in wrong just by touching the case and a good ground, BUMMER. So now we have made the plugs so that they will only fit one way a good thing no more getting shocked by holding the water faucet and waffle iron case. Remember this is before plastic. I have a pretty good collection of old waffle irons and I only use the more modern ones that are set to only one way that the plug will go in. Now the government came along and backed up by the copper wire co. they added the ground wire which goes from the neutral wire (metal case) to the neutral bar on the main box. Now what does this socalled ground wire do. Well it sure helps the copper wire co. Well anyway enjoy your stocks.
Walt
 
As always thanks. Just wanted to see what you thought.

The post above that was tragic, that would not have happened if the new guide lines of NFPA 70e were being followed. Just finished my last class(12 total, once annually) 3 weeks before I retired. I'll have to say that if NFPA 70E were followed there would be few if any accidents from electric. I did electric work(hands on) for 29 years and feel lucky I never got hurt by it. Yes I've been shocked and yes it hurt some but always walked away after the job was finished. So I did some the old way and a lot the new way. The new way is safer. It all comes down to training and culture change. Thanks
 
Walt, this ought to answer your question. And without the safety ground, if drill has internal short to case, the whole case goes to hot.
 
Thanks Walt, as it turns out I recently did own some shares of Copper but it lost money!!! as compared to my earlier investment in Silver which made good money, SO NO MORE COPPER STOCK FOR ME GRRRRRRR LOL

Yes indeed, Ive been in houses that had the old 2 wire knob and tube. Then it was discovered how much safer and how many many more lives could be saved and perhaps fewer houses burned down if a proper 3 wire ground system was used and it proved to be correct and lives were saved yayyyyyyyyyyy

Of course, if you prefer the old less safe 2 wire system THATS YOUR BUSINESS AND CHOICE AND IF YOURE WILLING TO BET YOUR LIFE ON IT YOU GET NO ARGUMENT OR CRITICISM FROM ME. Go for it

YES Walt, Im well aware of doubled insulated tools and 2 wire cords and plugs and how often its used NOT a problem, Im only talking about situations where the outer conductive metallic case frame of a saw or tool or motor or welder or appliance or implement is indeed attached to the third safety ground wire WHICH IS MUCH SAFER then if that fault current flows through your ticker grrrrrrrr. BUT THAT SYSTEM REQUIRES 3 WIRES YA REALIZE!!!!!!!!!!!! If only two and a short goes to the case fault current can seek a path through you instead of the third wire SORRY IM GOING WITH THE SAFER THIRD WIRE so fault current is in it instead of my heart, but you do as you please

Im here to help not fight or argue and since I know for a scientific fact (based on education and 40 years in the field) the current more modern NEC 3 wire system is safer, I choose for my home and family to use it.

I respect your choice and expect you in return to respect mine. Use whatever method you desire, no fight from me its your home and your life!!!

God Bless you and best wishes

John T
 
THANKS JMOR your picture is worth a thousand words, it may help Walt understand it I hope??? But hey I try my best to explain it and maybe save a persons life Im just no good at posting pictures lol

John T
 
(quoted from post at 12:44:57 07/10/14) John just how much stock do you own in copper wire. In the olden days we had two wires hot and neutral and a plug that could be put in either way so sometimes the case was hot and then turn the plug and the case is grounded. So we made plugs that would only go in one way then the case would never be hot. I grew up using these old systems and yes you could get a pretty good shock if the plug was in wrong just by touching the case and a good ground, BUMMER. So now we have made the plugs so that they will only fit one way a good thing no more getting shocked by holding the water faucet and waffle iron case. Remember this is before plastic. I have a pretty good collection of old waffle irons and I only use the more modern ones that are set to only one way that the plug will go in. Now the government came along and backed up by the copper wire co. they added the ground wire which goes from the neutral wire (metal case) to the neutral bar on the main box. Now what does this socalled ground wire do. Well it sure helps the copper wire co. Well anyway enjoy your stocks.
Walt

Spare us the conspiracy story.
The ground system is used to hold metallic equipment to earth potential in case of induction, lightening or insulation failure.
The ground system is not supposed to carry load current.
The insulated load conductor we call the neutral is not dead , it's live but the neutralheld close to true earth potential by the ground system. This also prevents the secondary side of the transformer from floating hundreds or thousands of volts above earth potential.
The triplex overhead service supply would never be allowed today but is "grandfathered" and used. Much like the two prong receptacles with same sized plug blades.Much better is an overhead quad or quad/four wire underground. Thing is most folk just want the cheapest way of making the lamps light up.
 
John,

As a fellow Electrical Engineer, I must confess that Ihave violated the prime directive and used a four conductor double plug to back feed.

I have verified the disconnects, and locked out the breakers.

My bad.
 
Hey just because I know the RIGHT way to do things sure doesn't mean around the farm when in a hurry I haven't cheated a bit at times myself lol

John T
 
Good info John. I know I occasionally cheat a little, but I always keep in mind, don't set a trap for someone else!

It's been pointed out before, the things we do live on long after were gone. Just because I know how to connect the generator doesn't mean my wife or kids or the next owner of the property will!

And the fed back problem... Yes, linemen are trained and equipped to watch for it. But what about the volunteer clean up crew that comes after a storm? Or anyone else walking around downed lines, even the secondary line to the house. If it's on the ground and hot...
 
I hear ya Steve, as I get older I actually worry about things such as if the wife and kids will know how to do this or that or how something works safely when I'm gone, sooooooooo like you I try NOT to set traps and am starting to leave written tid bits of information for them and go figure, I do all sorts of estate planning documents for my clients BUT DONT HAVE MY OWN HOUSE IN ORDER GRRRRRRRRRRRRRR.

John T (Do as I say NOT as I do lol)

John T
 
when I looked into it when the grid went down the solar system automatically disconnected from the grid . I understood it was a magnetic switch that dropped out?
 

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