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MtnDon
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# Posted: 3 Feb 2016 11:47pm - Edited by: MtnDon
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Mike Holt Video on Grounding Myths and NEC, 2014 Maybe help? Confuse? I have not watched it yet, just passing on the link.
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pizzadude
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# Posted: 4 Feb 2016 01:01am
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MtnDon
Your friend is knowledgable on the subject.
However, I personally wouldn't bond N/G at the genny but rather at the main panel itself, stressing again the assurance that there be isolation between normal power and the separately derived system. It makes most sense to me simply because it's the easiest and safest(I think).
My way may or may not meet code requirements
MDon, your friend is probably right on
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bldginsp
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# Posted: 4 Feb 2016 08:59am
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Soare's book on grounding is the definitive source on grounding and bonding, and covers standard generator installations well.
But that book does not raise the issue of different generator configurations and how that affects the use of a generator for powering up a panel.
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Defndr
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# Posted: 4 Feb 2016 09:52am
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I could not get Champions tech to commit to anything concerning my application. I'm sure they do not want any liability.
They did say "If your panel is already bonding the neutral to ground you will want a floating neutral generator you do not want two bonds".
I see in the wiring diagram the L14 plug does have 2 hot wires a ground and a white wire that I assume is the neutral. I will try to pin them down today to answer the question about a true neutral on this generator.
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bldginsp
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# Posted: 4 Feb 2016 03:23pm
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There must be two wires in either scenario. One way to tell is with a volt meter- you should 120 or so on one side and none on the other. Be interesting to hear what they say.
I started a thread on Mike Holts website asking about generator configurations, I'll post here if I get something useful.
It's fun learning about the theory here, but you don't want to be testing theories with your installation. I agree that if there is any doubt at all, hire a licensed electrician.
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toyota_mdt_tech
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# Posted: 4 Feb 2016 09:18pm
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I suspect a true neutral is more likely on a 220VAC generator. Usually the 110VAC is tapped at the common point in the middle of the winding for a neutral and one of the 2 legs would be line. Line to line means 220VAC while neutral to line means 110VAC. I suppose the exception to this would be if the generator just stepped up or stepped down the voltage via inverter.
My Honda EU6500is has a large HD rocker switch I flip if I am using it for 120VAC ONLY, or flip it for "120/240VAC"
OK, found the wiring diagram, I am seeing 2 sets of stator windings, both 3 phases with a "Y" as in wired in a "WYE" formation. But the Y isnt tapped at all.
Wiring diagram for my Honda EU6500is, go to page 77
http://cdn.powerequipment.honda.com/pe/pdf/manuals/00X31Z256200.pdf
Look, bottom left of page, see stators (2)
No neutral at all. And the outlets are not grounded. Its just chassis ground. So the inverter is taking 3 phase of AC (X2) with no neutral (there, just not tapped) and phase U, V and W and this is the input to the inverter. The output is just line and line, no true neutral and the ground is just at the chassis. No actual ground, its a bond to generator chassis.
So my hunch is, if you have an inverter generator, there is no true neutral. Now I use mine at home, my main panel is bonded, sub panel is not, I get no electrical shock. But as mentioned, overload protection and short circuit, but probably no fault current protection.
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Steve_S
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# Posted: 5 Feb 2016 06:51am
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Quoting: Defndr I could not get Champions tech to commit to anything concerning my application.
Can you tell us the Model # of your Genny, Champion makes quite a lot of them.
I have a 7200/9000 Model # 41552. The doc's for mine state the obvious disclaimer of "get an electrician" absolving Champion of liabilities... (just gotta luv lawyers eh ? NOT)
From my docs:
Grounding
Your generator must be properly connected to an
appropriate ground to help prevent electric shock.
A ground terminal connected to the frame of the generator
has been provided on the power panel. For remote
grounding, connect of a length of heavy gauge (12 AWG
minimum) copper wire between the generator ground
terminal and a copper rod driven into the ground. We
strongly recommend that you consult with a qualified
electrician to ensure compliance with local electrical codes.
Grounding
The generator system ground connects the frame to the
ground terminals on the power panel. The system ground is
connected to the AC neutral wire.
Champions online manuals are available here URL
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bldginsp
Member
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# Posted: 5 Feb 2016 08:15am
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Here's a good read if you have the time:
http://www.thehulltruth.com/boating-how-s-kerno-memorial-forum/555711-portable-genera tor-shore-power-issue.html#b
It's a boating forum where they discuss issues with providing a boat with power from a generator or from shore power, which basically duplicates what we are dealing with- generator alone, utility power, or both? The eighth poster proves that some generators do achieve 120 with two 60v legs. But this doesn't mean that when the generator is used for 240 that there is no neutral provided to that circuit. If you are powering up a panel, you should only use the 240 source to do so, of course.
A lot of unanswered questions here about generators, and a lot of confusion about proper grounding/bonding requirements for use of generators as alternate power, or as single source. Here are a couple of general rules that will cover most situations with most generators:
-If the manual of your generator says that the neutral is bonded to the frame and/or ground, you can use that to power up a panel with the 240 outlet and you have the ground/neutral bond at the generator which will cause breakers to trip in the event of fault current. Isolate neutral from ground at the panel.
-If the manual of your generator or a label on the generator says that it has a floating neutral, or that the neutral is not connected to frame or ground, you do not have this bond and the bond must be made at the panel.
- If you are not sure, get an electrician. You don't want to end up with a system that has no ground fault protection. Ground fault is when a piece of equipment screws up, or hot wire insulation gets frayed and the wire touches metal, and in any event you have the metal frame of your tool, light fixture, washing machine or whatever with hot current on it just waiting for someone to touch it and get shocked. The main reason for ground wires in circuits is to throw the circuit breaker when this happens, and the breaker can only throw if the ground wires are bonded to the neutral at the source, or somewhere.
There's more to it than just that, but that's the gist. Read Soare's Book on Grounding for the complete story. It is published by the Int. Assoc. of Electrical Inspectors, and is the 'bible' of grounding/bonding.
As for the issue of different generator configurations I have to confess my ignorance. I doubt that anyone is willing to make blanket statements about all generators because no one knows what might be on the shelf tomorrow. If you are buying a generator to power a cabin, get one where the manual says specifically that it bonds neutral to the frame and/or ground. This is the simplest way to be sure you are powering up your cabin the safest way.
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toyota_mdt_tech
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# Posted: 5 Feb 2016 09:01am
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Quoting: bldginsp If you are buying a generator to power a cabin, get one where the manual says specifically that it bonds neutral to the frame and/or ground.
bldg_insp, so are you saying neutral/ground bonded to frame as in either or or both? I have no neutral, and really no ground unless I poke a rod in the ground.
Mine has no ground, the ground at the outlet is hooked to the generator chassis/ground screw. So I take it I should bond my neutral lug at the panel to my ground? This would be an easy task.
I am off to work now, I will read that link you provided. This has been a great thread, very educational for me. Appreciate all the input too.
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bldginsp
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# Posted: 5 Feb 2016 03:13pm - Edited by: bldginsp
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Not sure exactly what you mean Toyota- do you mean your generator has no neutral?
Both neutral and ground should be bonded to frame if bonding at the generator.
For any premises wiring system, there should be at least one electrode earth connection- a ground rod is the usual one. The generator frame should be bonded to this and the panel, but if the generator is used elsewhere it's kind of a pain to disconnect and connect it each time it is used. If the generator is not going to move, connect to the ground rod. Where the bond is at the generator, the EGCs (equip. grounding conductors, or green or bare ground wires), and electrode connection, and neutral and frame all are connected together.
Where the bond between ground and neutral is not made at the generator, but the generator has a neutral (and most do, whether the bond happens at the gen or not), bond all grounds, electrode and frame together, then bond ground and neutral elsewhere. Or, create the ground neutral bond at the generator.
If your generator has no neutral it will do no good to bond neutrals and grounds at the panel. But if your generator has no neutral, your panel won't work except for 240 across two legs.
Hope this helps.
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Defndr
Member
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# Posted: 9 May 2016 10:15am
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Just a quick update. I have been really busy on other projects so I just finally got around to finishing up the wiring and testing it out.
Thanks again to all who helped me out on this.
Since mine was a floating neutral generator I bonded the ground and neutral in the panel and ran a rod in the ground at the panel. I purchased 50 feet of heavy wire that is rated to be buried and attached L14 ends. This worked for my application.
Its nice to have lights and plugins. Future plans are to bury the wire and build a generator shack to help keep the noise down.
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bldginsp
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# Posted: 9 May 2016 02:14pm - Edited by: bldginsp
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Since you used a floating neutral generator, you should not switch the neutral at the transfer switch, so that the ground/neutral bond at the panel works when the generator is operating. This is a typical setup for a backup genny.
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