Double-checking on grounding wire?

Rossman
Rossman Solar Expert Posts: 178 ✭✭
in Off Grid Solar & Battery Systems #1
G'day,

Was hoping someone here could just help me confirm I am doing things correctly. We are 100% off grid up here in Ontario, Canada.
We have a XW6048 and are going to connect the AC output of that into a 200A service panel. We will charge our batteries with solar and also the trusty Honda generator.

My question is about my grounding wire. I purchased a long run of #6 copper, I have understood that keeping the ground wire continuous with no cuts is the best approach, so my plan is to run the ground from the XW power distribution panel ground bar, to the ground bar in the 200A AC service panel, then out from there to a grounding lug on our 3/4" black iron propane pipes, and then outside to the grounding electrode (which I have buried down to bedrock here 3' down or so - as far as I can go). I was planning to not terminate at the electrode but come back up out of the ground and terminate the #6 on the ground lug on our Honda EU7000. I don't need to connect to the plumbing system as it is all pex/non metallic piping.

I would appreciate any insights or tips on this, if I have gotten it wildly wrong, etc, please do let me know, I would like to get it right the first time before the ESA inspector comes out! If I run the wire it would be a real pain to have to undo, and redo it all!

Thanks kindly in advance,
mark
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Double-checking on grounding wire?

    Mark;

    This is not a case where the ground conductor needs to be continuous.
    One run from the charge controller XW's case and AC output to the service panel to the ground rod.
    Another run (all outside the house preferably although code says otherwise) from the panel frames & mounts to the ground rod. This is the line that needs to by code be contiguous from panel to panel (even though that is in practical terms redundant).
    The generator can be grounded through the XW using the ground connection on the AC IN (AC2 usually with an XW & gen).
    DC negative can have its own line & in fact its own ground rod.

    The gas lines should have their own line to the ground rod.

    The grounding rod is the termination point for ground conductors. It does not matter if each item has its own line going to the rod or if items are ground-connected 'in series along the way'. Sometimes if the runs get too long additional ground rods are installed so that the resistance in the conductor is not too high. These may be connected to the main rod or not, depending on the circumstances.

    If inspected, however, the system must ultimately be as the inspector says it should. Even if that is wrong from an engineering POV. (You can always fix it so it works after he leaves.)
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #3
    Re: Double-checking on grounding wire?

    Thanks very much for your prompt response!

    Because of the weather I will unfortunately not be able to get my panels set up until spring (snowed in pretty good already up here), so I will have to do all my recharging via generator (right now we are living off generator 100% so not such a big change).

    Am I correct reading that, that the generator ground lug does not need to be connected? That the necessary grounding will occur via the 240VAC outlet instead?

    Sorry if these are dumb questions, I would love to just pay someone to do all this but the budget unfortunately does not allow that option :(

    Cheers,
    mark
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Double-checking on grounding wire?
    Rossman wrote: »
    Am I correct reading that, that the generator ground lug does not need to be connected? That the necessary grounding will occur via the 240VAC outlet instead?

    This depends on the generator's wiring which varies from one to another. The ground connection on its output may or may not be connected to the case/frame ground. You can check this with an Ohmmeter. Also check and see if the neutral line is floating or grounded.

    What you don't want is a situation where the gen frame is connected to the ground rod, and the rod connected to the XW case & AC out which is in turn connected the the AC feed from the gen and connect to the gen frame. If you think about that (rather poor wording) it would form a ground loop between gen, rod, and XW which is something to be avoided.

    Better to have each device run its own line to the ground rod like a spider's web. But since there is a ground wire in the AC connection you have to know what's going on with that. Use it if you can.
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #5
    Re: Double-checking on grounding wire?

    Thank you again! I will put my DMM across AC neutral & AC ground, and also AC ground & the ground lug of the generator, to see whats going on. IIRC correctly my EU7000 says "this generator has a floating neutral" or some such on the front of it, but I would have to look again to be sure of the wording. Anyway the DMM will get to the bottom of it, thanks. I may post back again if I confuse myself ;)

    Thanks, and happy holidays!
    mark
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #6
    Re: Double-checking on grounding wire?

    I checked out my generator today, it seems AC ground is bonded to the ground lug on the frame, and neutral is also (so, neutral bonded to ground).

    I assume this just mean I should remove the neutral -> ground bond strap in my service panel, and that I do not in fact need to use the ground lug on the generator.

    Thanks,
    mark
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  • Hill_Country
    Hill_Country Solar Expert Posts: 96 ✭✭
    #7
    Re: Double-checking on grounding wire?

    Hi Rossman,

    We are doing a very similar thing as you...we will be 100% off-grid. As my signature line specifies, I've got a Magnum MS-4448PAE (48v - 120/240v AC) inverter along with a battery bank, Magnum Mini Panel (has all the breakers and the interconnection with the charge controller and batteries), as well as a standard GE Load Center (125amp - main breaker). In addition, I have a 'somewhat' similar portable 120v gasoline generator, albeit a much less powerful one (Yamaha EF2000iS generator - comparable to a Honda EU2000i) that only does 120v. Anyway, we will be using the portable generator to charge the batteries during extended periods of cloudy weather, or during times of higher usage. I'm in the same boat as you in regards to grounding the Magnum Mini Panel/Magnum Inverter, along with the AC load center, plus a portable generator.

    In terms of grounding, I asked a very similar question here: http://forum.solar-electric.com/showthread.php?23677-Solar-array-and-grounding The main difference was that my two PV arrays are 125ft. from the MMP/Inverter/AC Load center/house, so grounding is critical (plus lightning protection). Perhaps this will help you somewhat. I plan on running a continuous grounding wire (#6 AWG bare copper wire) between the two PV arrays (see link for further description), in which both PV arrays have their own grounding rods located nearby, direct burial of this bare #6 copper wire to the house 125 ft. away, then connecting to a third grounding rod (which will also have a grounding wire from the AC load panel and from the MMP/Inverter).

    So each PV array has it's own ground rod, plus a house ground rod (three ground rods total...all tied together by a continuous #6 AWG bare copper wire), all connected by a direct burial #6 bare copper wire. In terms of the portable generator, I will just use the ground on the portable generator's plug and let that be the ground. Portable generators are a different story when it comes to grounding. It totally depends on whether the generator has a neutral-to-ground bond already, or whether the neutral floats...but you've already determined that!

    Thanks!
    100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #8
    Re: Double-checking on grounding wire?

    Thanks Hill_Country, I really appreciate the response!

    For right now, because I will not have my solar array functioning yet, I will just run from the Xantrex power distribution panel ground rail, to the 200A AC service panel, then outside to the grounding electrode. I will do a separate run from the black iron propane pipes, directly to the ground rod.

    Thanks kindly and happy holidays!
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #9
    Re: Double-checking on grounding wire?
    Cariboocoot wrote: »
    This depends on the generator's wiring which varies from one to another. The ground connection on its output may or may not be connected to the case/frame ground. You can check this with an Ohmmeter. Also check and see if the neutral line is floating or grounded.


    Were talking AME power 120/240 gensets in North America
    Here I Myself would use VOLTS between Hot & neutral ,neutral & ground , under load and not . Ohmmeters can be misleading if there are GFI's or other sensing circuits involved , plus Ohm smoke or BUSS fuses are expensive. Power potential lets you know who's connected.

    VT
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #10
    Re: Double-checking on grounding wire?

    Thanks CDN_VT, I will have a go at your approach also, though I am not as familiar with what the results are going to tell me.

    Cheers,
    mark
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #11
    Re: Double-checking on grounding wire?

    Well do some checks in the voltage range & see. Record & post back here . Many will help . But Im leery on using ohms /amps on a meter until YOU KNOW what your measuring & how much & HOW . Volts is the first & forgiving , start high scale 200 for a 120V circuit ,400 on a 220 .

    Even I get them wrong as everybody has , I stock many fuses for this reason.
    EG :
    Power readings from ground to either side of the plug is 55V bout from blade to blade ground left out gives you 110V ground to case is zero tells me no neutral bond.

    Many different reads can effect the way it's designed & built


    VT
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #12
    Re: Double-checking on grounding wire?

    Ok, thanks again CDN_VT...I'll take some measurements tomorrow as you suggest.

    Cheers!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Double-checking on grounding wire?
    CDN_VT wrote: »
    Even I get them wrong as everybody has , I stock many fuses for this reason.
    VT

    Speak for yourself. :D

    I'd rather do an Ohm reading on a shut-off gen than a Volt reading on a running one.
    So far I'm still alive, and so is my multimeter (which I've never blown a fuse on any of them ever in 40+ years).
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #14
    Re: Double-checking on grounding wire?

    I found this picture I guess I took a while ago, I guess the label on the 220V outlet confirms, neutral is bonded to frame/ground.

    Attachment not found.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #15
    Re: Double-checking on grounding wire?

    Nice that they put that right on there!
    Some gens you can read the manual backwards and forwards and they still don't give a clue.
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #16
    Re: Double-checking on grounding wire?
    Cariboocoot wrote: »
    Speak for yourself. :D

    I'd rather do an Ohm reading on a shut-off gen than a Volt reading on a running one.
    So far I'm still alive, and so is my multimeter (which I've never blown a fuse on any of them ever in 40+ years).

    Nice !! You do know that Many Read here !
    If I was only so perfect

    VT

    Well that answers the bonding , But just for experience , test out the voltages , and make sure , next time it will come EZ2U .
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #17
    Re: Double-checking on grounding wire?

    Gotta love a Honda! Unfortunately, I would love to remove that neutral->ground bond in the generator, as there is one in my service panel already, and I'm pretty sure the inspector is gonna be looking for it there. (ie. what happens if I unplug the gennie and neutral&ground become unbonded).

    I found this delightfully vague PDF, "Honda Service Bulletin #20", that talks about removing the bond but isn't as specific as I would like..
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #18
    Re: Double-checking on grounding wire?

    Is it just me or did Xantrex get the ground wire wrong in their documentation (at least in the following diagram)??

    Attachment not found.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #19
    Re: Double-checking on grounding wire?

    Yeah that's wrong: shows two green ground wires going to the main service panel and none going to the sub panel? Not right.

    You can solve the dual N-G problem with the Honda by leaving the ground wire to it disconnected. Then connect the frame ground directly to the ground rod. That way there's no potential parallel path along neutral and ground between generator and service panel.
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  • Rossman
    Rossman Solar Expert Posts: 178 ✭✭
    #20
    Re: Double-checking on grounding wire?
    Cariboocoot wrote: »
    Yeah that's wrong: shows two green ground wires going to the main service panel and none going to the sub panel? Not right.

    Thanks yeah, that's what I thought!

    Cariboocoot wrote: »
    You can solve the dual N-G problem with the Honda by leaving the ground wire to it disconnected. Then connect the frame ground directly to the ground rod. That way there's no potential parallel path along neutral and ground between generator and service panel.


    Oooh, interesting, so I don't need to open/modify the generator! That's pretty exciting (and makes my life easier)! I will run a length of #6 from the generator ground lug to the ground rod, then leave the ground wire disconnected when I wire the NEMA L14-30 plug as you suggest!

    Amazing, such great help here! Woo!
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