generator ground

Ethan Brush · January 2015

Re: generator ground

oil pan 4 wrote: »

To avoid running current on your ground you wire the generator through a sub panel where the neutral and ground are separated.
If you wire it to the main panel then you end up hooking the neutral and ground to the same bus bar and the ground carries current.

Think about that again. Follow the current and I think you will see it doesnt matter if its a sub panel or not. As long as the N/G bond at the genny is removed, there will not be normal current flowing on the genny feeder EGC. Besides, note that the neutral and ground in a sub panel are still electrically connected, just not in that sub panel.

If I went from a service panel that I already have; could be the service to the garage or the ac breaker panel that came with the inverter, and put a new breaker in it and built a immovable plate that insured that only the generator breaker or the main panel breaker was on at a time, I would in effect have a safe ul aproved generator transfer switch.

Well I dont know about UL approved, but if they are mechanically interlocked, you should be safe!

gww1 · January 2015

Re: generator ground

Ethan
Thanks
gww

Ethan Brush · January 2015

Re: generator ground

gww1 wrote: »

To hard wire from a 4 prong plug to my breaker box.

1. remove the jumper That bonds neutral to the ground from inside the gen.

2. run the neutral from, each gen. stator, as one wire to the ac breaker panel neutral/ground buss bar.

3. Run the ground as one wire to the ac breaker panel neutral/ground buss bar.

4. Run the two gen stator hot wires independantly to breakers in the ac breaker panel.

5. Make an interlock for the ac breaker panel that makes it impossible for the ac breaker panel grid to provide power at the same time as the gen. breakers do.

This would be the exact way that the inverter ac breaker box on the inverter is set up now.

The gen would get its ground from the garage ac box where the neutral is bonded with ground but the paths from the generator to there would be independant.

If I put a sub breaker box prior to this it would have no ground untill it reached the garage anyway, so in the end seems to be the same thing.
Thanks
gww

Sorry somehow didn't see this post. Yes sounds exactly correct.

gww1 · January 2015

Re: generator ground

Ethan

Yes sounds exactly correct.

That was the goal. Thanks very much. It is nice to get a bit of confirmation (love my spelling?). I feel good enough to order what I don't already have and move forward now. I would report the end result but it might be awhile before I do it and sometimes the threads get lost or too old but I'm sure it will come up again and I couldn't even try without the below conversation, cause I have been thinking and studying but only now have the pieces come together.
Thanks
gww

oil pan 4 · January 2015

Re: generator ground

Is that common practice to remove the Neutral and Ground linking bar?

The large stationary facility power generators I have worked on have had their neutral and ground bonded.

gww1 · January 2015

Re: generator ground

Oil pan

Is that common practice to remove the Neutral and Ground linking bar?

I don't know for sure but I have been looking on the net since I even knew there might be an issue and most of the info seems to be yes. I have spent several days over several months trying to make sure. One thing while talking to electritions when I worked is that certain grounding practices where acceptable for commecial work that wouldn't work for a home. What comes to mind is multiple ground rods and equiptment spicific ground rods. Then again the electrition I was talking to may not have been good or I might have been so dumb I didn;t understand. I have spent some time and do feel comfortalble to go ahead and try it cause sooner or later I want to and it won't get done if I don't try anything.

I am always willing to listen more.

I do get confused with grouding and hounestly most explinations of why just confuse me more. Putting two and two together though it seems this is correct. I only understand a,b,c instructions like the way I presented what I was going to do. Not always the why.
Thanks
gww

Ethan Brush · January 2015

Re: generator ground

oil pan 4 wrote: »

Is that common practice to remove the Neutral and Ground linking bar?

The large stationary facility power generators I have worked on have had their neutral and ground bonded.

Electricians (such as myself) are quite familiar with the generator N/G bond issue as it is an important part of determining if a generator is/can be a separately derived system. An SDS is an electrical system that has no electrical connection, including a solidly connected grounded conductor, to a utility system. Most commonly encountered SDS is the secondary of a transformer - remember energy is transferred between the two windings of a transformer through a magnetic field so there is no direct electrical connection between the primary and secondary. Thus the secondary has no "association" with the primary and all system grounding "resets" so it is important to reground the system (unless you are keeping it ungrounded for some reason). Anyway so you can see from the definition of SDS (and some parts of 250.24 and 250.30), that if the transfer switch switches the Neutral, than it IS an SDS, N/G bonded at genny, grounding electrode connected. IF not, separate N/G at genny, no GE required, separate neural and ground conductor. Small consumer generators are often at odds with the NEC considering that most (easy and cheap) transfer methods and equipment dont switch the neutral. Honestly, I dont worry about it when connecting one. I dont try to dissect the generator to remove the bond or tell the customer I cant connect their generator. So you have a parallel path on the EGC with neutral current, but its insulated the whole length anyway - in the SO rubber cord and in the (typically) Romex between the transfer switch/interlock and the inlet box. Also considering the infrequent use of these for home backup purposes, Im ok with not being a code nazi when it comes to these. Note I am talking about portable generators here. "home standby" generators that come with a transfer switch are always set up right from the factory.

gww1 · January 2015

Re: generator ground

Ok, I put a L14-20 plug for 240 volts on the generator. I thought I might re-afferm one item that I think is ok but thought I would ask just in case.

When hooking the four pole plug, it will have a white wire, a ground wire, a x wire and a y wire. It is my belief that the x wire and the y wire are interchangable. Am I correct on this.
Thank you
gww

inetdog · January 2015

Re: generator ground

gww1 wrote: »

It is my belief that the x wire and the y wire are interchangable. Am I correct on this.
Thank you
gww

Yes, you are correct.

gww1 · January 2015

Re: generator ground

Inetdog
Thank you
gww

inetdog · January 2015

Re: generator ground

gww1 wrote: »

Though I have read the recent post on generator grounding, I am dence and decided to just ask a simple question that I do understand.

I have a devilbiss 5000 watt generator. If I wanted to hook it to my outback inverter with a manual transfer switch could I get my ground by running a wire from the frame of the generator to my house ground?

Thank you
gww

Yes. It may not be completely up to the applicable electrical code, but it should work fine as long as you use a large enough wire for the ground.
Note that if your deVilbiss machine bonds the grounded conductor (aka neutral) to the grounding (safety) conductor, then your manual transfer switch should interrupt the neutral wire as well as the two hot wires.

gww1 · January 2015

Re: generator ground

Inetdog

I will explain how I wired it and see if I made a floting neutral out of the generator or not. I may not explain it clearly though.

What I did. I removed a jumper wire from the 110 dual plug ground nut that was on the same side and jumped to the dual 110 neutral wires.
I took the one wire that was running from that same point on the 110 plug over to the 240 volt three prong plug ground lug. I assumed because of the jumper on the 110 plug that this was the 240 volt neutral cause the two wires, one from each generator coil were also connected with the ground jumper.

I took this wire and put it on the neutral "White " prong of the 4 prong plug .

The other two wires that came from the generator stators went to the push button breakers. I considered these the x and y wires. I hooked them as they were also hooked to the 3 prong plug and put one on the x and one on the y prongs of the 4 prong plug.

I took a 10 awg wire and hooked to the ground prong on the four prong plug and wire nutted it to the jumper that was remover from the neutral and was now just a wire on the ground screw of the 110 plug. I ran the two wires that were connected to each other and a lenth of wire and connected this to a ground lug on the frame of the generator. These wires were the ones connected to the ground nut of the 110 plug and the four plug ground prong.

I used 10 awg for the ground wire. I am wanting the house to be the ground point.

What do you think?
Thanks
gww

inetdog · January 2015

Re: generator ground

gww1 wrote: »

Inetdog

I will explain how I wired it and see if I made a floting neutral out of the generator or not. I may not explain it clearly though.

What I did. I removed a jumper wire from the 110 dual plug ground nut that was on the same side and jumped to the dual 110 neutral wires.
I took the one wire that was running from that same point on the 110 plug over to the 240 volt three prong plug ground lug. I assumed because of the jumper on the 110 plug that this was the 240 volt neutral cause the two wires, one from each generator coil were also connected with the ground jumper.

I took this wire and put it on the neutral "White " prong of the 4 prong plug .

The other two wires that came from the generator stators went to the push button breakers. I considered these the x and y wires. I hooked them as they were also hooked to the 3 prong plug and put one on the x and one on the y prongs of the 4 prong plug.

I took a 10 awg wire and hooked to the ground prong on the four prong plug and wire nutted it to the jumper that was remover from the neutral and was now just a wire on the ground screw of the 110 plug. I ran the two wires that were connected to each other and a lenth of wire and connected this to a ground lug on the frame of the generator. These wires were the ones connected to the ground nut of the 110 plug and the four plug ground prong.

I used 10 awg for the ground wire. I am wanting the house to be the ground point.

What do you think?
Thanks
gww

From your description of "the 120V ground lug" and "the 240V ground lug", it is not clear whether you are referring to the grounded neutral wire which is intended to carry current or the grounding, safety conductor, usually a green wire, which is intended to carry current only in case of a fault.
If you want the house to be the only point where the neutral and ground are bonded together (for code compliance as well as to allow for a GFI at the generator and for general safety), then there should not be any connection anywhere at the generator between any neutral wire and any ground wire. You can verify this with an ohmmeter with the generator unplugged and not running. If there is continuity, then you have missed a grounding jumper.
As far as which neutral to use and which ground wire to use, the 120V and 240 neutrals should all come together at a common point at the generator windings, and the 120V and 240V ground wires should also be tied together so that it does not matter which you use.

gww1 · January 2015

Re: generator ground

Inetdog
I forgot one thing. I should have checked my work with an ohm meter. I will do so.

I hooked the generator up today but the outback did not accept it. The mate showed that the generator was averaging 114 volts on one leg and 117 volts on the other leg coming from the generator. No current from either leg. It was not unexpected as thats why every one uses inverter generators. All is not lost as it is hooked up were I should be able to run my loads in by-pass with just the generator though I didn't try that yet cause I didn't want to have to set all my clocks today cause I turned the power off. I was a bit disapointed cause I still have no way to charge my battery if the grid ever did go down and the wheather was bad. They would have to sit there in a discharged state. I didn't expect it to work but thought maby if I kept the loads really low I might get lucky on the steadyness of just charging. Oh well. I still intend to ohm it and check my connections.
Thanks
gww

Ps the only way to explaing the 120 volt plug and the 240 volt plug is the the green nut on them now have a wire to the frame insted of having a jumper on the 120 volt plugs that went to where the neutrals where connected. I can not use green as the wire color as that is one of the colors coming from one of the 110 stators. I should know the answer by ohming from the neutral to the frame. I won't know where to go next if it comes out that it is connected to ground at the point of the stator.

gww1 · January 2015

Re: generator ground

I think I will run one more test today to make sure the generator still works. I hooked it to my garage breaker panel but my garage lights go through tie inverter. All my plugs in the garage go to the garage breaker panel. I will plug a circular saw in and see if it is running that whole garage. Then I will know if it is putting out amps to go with the voltage the mate says it is putting out.
Gww

gww1 · January 2015

Re: generator ground

I checked with an ohm meter. I put it in the neutral socket and one leg of the 240 volt socket and got a reading of .13 which told me I had contact with metal in the socket. I then removed the lead from the one leg of the 240 volt socket and touched that to a bare spot on the generator frame and the meter stayed showing a 1. I would say I got the grounding correct.

I also restarted the generator and plugged a jigsaw and an angle grinder in a plug in the garage and ran both at once. The leg with the 114 volts climbed to 118 during this per the mate and the motor on the generator did not speed up or change much if any.

I guess the inverter is just not going to accept the generator output.
gww

gww1 · January 2015

Re: generator ground

I got the outback G inverter to accept my devilbiss generator by speeding up the idol. I didn't have very heavy loads, probly 700 watts or so. I couldn't get it to charge the batteries regaurdless of settings. My guess is there is some programing in the inverter that imput voltage has to be high enough. One leg of the generator was only putting out about 113 volts and the inverter showed the volts leaving it was 111 volts to the loads. I put it back on grid and the charging went on like normal. I couldn't tell if generator support was actually working and the generator was carrying the full load and the mate said pass through bulk on it. The mate said the generator was only carrying 5 amps but it should have said more cause when I switched to grid it said it was carrying .7 which adds up to about 1000 watts in real life. It took an hour and a half to figure out how to get the inverter to accept the generator but at the end it seemed to stay connected. I didn't however have anything big kick on. It will be pretty in efficiant running a 5000 watt generator with a 500 watt load cause I can't get the battery to charge.

I know I am working with junk stuff and if I had two hondas for 240 volts I would probly have no issues but I have this devilbiss already and hve never used it once during an outage yet and figure it is something to play with and may work well enough if I ever did have a couple day outage. I would probly do better it I ever get an 48 volt battery charger.

Just an update on how I waste my time.
gww

mike95490 · January 2015

Re: generator ground

try using a 120V kill-a-watt meter set for frequency, to see what speed your genset is actually running. You want to set it for about 60.5Hz no load.

oil pan 4 · January 2015

Re: generator ground

I looked up generators in my 2014 code book and you do sever the neutral ground bond if needed, but the generator set needs to be clearly labeled as such.
I think next time I go into my generator I am going to remove the N-G bond and connect the NG bond to a heavy duty light switch.
Turn the N-G bond "on" for stand alone operation, turn the N-G bound "off" for residence backup power.
Code book doesn't say I can't so long as I clearly label it.

gww1 · January 2015

Re: generator ground

Mike

try using a 120V kill-a-watt meter set for frequency, to see what speed your genset is actually running. You want to set it for about 60.5Hz no load.

This is above my pay grade with out research. I think that my sears clamp meter has a way to measure frequency but I don't know how to use it as of yet. I did the trial and error of speeding the idel or lowering it while seeing what the output voltage was and whether the outback would accept it. The out back did reconize it enough to pass the power through but not enough for the charger to work.

There is enough of a differance in the voltages of the two generator leggs that one side will get pretty low voltage passing depending on the motor speed. I am going to try and learn how to do the frequency thing but do need to know which is the highest priority, frequency or voltage?
Thank you
gww

gww1 · January 2015

Re: generator ground

Oil pan
I made an extra 240 volt plug and only put a jumper from the ground to neutral in it, I should be able to use 110 in moble apps. I don't exatly know how to ground it if I wanted to use the 240 volts for like a rv ac or something as it now only has one 240 plug.
gww

gww1 · January 2015

Re: generator ground

I also wonder about the mate firmware that I am using. I don't know if my generator support is working like blackcherries and mtdocs is cause it could be the generator only passing through or it could be 10 year old software on the mate. It take several cycles to before the inverter accepts the imput and then seems to only be a pass through mode. I think my next experment may be to use the gen setting in the mate and use the grid power set at about 5 amps per legg and then see if the battery helps the load when a larger load then the imput amps kicks on. I do know that when I use the grid with the same settings I have for the generator that the inverters battery charging does work so I am sure dirty generator power is a big part Of the issue.
gww

oil pan 4 · January 2015

Re: generator ground

US spec for 120 volt AC power is any where from 114 to 125 volts.
As long as you can stay in that range your devices should work.
Then you just have to get the generator frequency where the devices are happy.

I run mine at 62 to 63 Hz because I apply massive power demands to it. My most advanced piece of machinery I run off my generator is my old inverter based miller 625 plasma cutter. The plasma cutter doesn't cut out until the generator boggs down below 50Hz. I know this because years ago when I bought it new, for years all I ever ran it off was 50Hz grid power.
I can hear the generator slow down a lot before the plasma cutter finely kicks off, then I just back the power level adjustment knob off a hair and it works fine.

So if your charger machine is not picking up generator power because it not 99.99% pure 60Hz grid power that is because the manufacturer set it up that way. Not because slight fluctuations are some how deficient or damaging to the technology.

gww1 · January 2015

Re: generator ground

Oil pan
A couple of trials with it while doing adjusting had the voltage down to 111 volts and I am sure that the longer the wiring to the powered device has some affect. My very first powered stuff is probly 70 feet away and the furthest is probly another 60 feet. The inverter has a pretty tight hertze band. I would like to learn how to use the my multi meter to check the hertz and as soon as my head quits hurting from the thought of more knowladge, I am going to look up how to do it.
Thanks
gww

oil pan 4 · January 2015

Re: generator ground

60 feet? What size cord are you using?

Post a pic of your multi meter and I might be able to tell how to set it for Hz.

gww1 · January 2015

Re: generator ground

This is my meter.

http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P?redirectType=SRDT

I used direct burial I can't really remember, from the aray it was 4/0 alum and what I ran to the house was direct burial alum also. I think the 4/0 was 200 amp and so to the house I believe was 100 amp wire. I think it was 2/0 alum but my mind is going and I can't remember for sure. I am pretty sure it was 100 amp service wire alum for the 60 feet to the house.

Man it is bad when my memory is going like this.
Thanks
gww

oil pan 4 · January 2015

Re: generator ground

To measure frequency looks like you need to turn it to volts setting. Then hit the gray button that says Hz. If that doesn't work. Turn it off and put it on volts and hit the gray button that says mode.
One of those 2 should give you an Hz reading.

2/0 gauge or 4/0 gauge aluminum should be more than enough.

Either one should give sufficient amount of conductor.

gww1 · January 2015

Re: generator ground

oil pan
This may sound stupid but what do I touch the meter leads to and I am asuming that it will be done while the generator has nothing plugged into it (no load)?

Thank you
gww

BB. · January 2015

Re: generator ground

Measuring Frequency is just like measuring voltage--Just put the meter across the two terminals you want to measure the frequency of.

Note that non-sine wave type wave forms can cause frequency meters to read "way off"... MSW can read 2x the frequency and some generators (especially with battery charger as a load) may not have a good sine wave voltage either--So don't panic if the frequency is way off--It may not be.

-Bill

gww1 · January 2015

Re: generator ground

Bill
Thank you. I can do my measure unloaded though, right?
gww

generator ground

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