[RE-wrenches] Magnum MS4024 grief

Sindelar Solar Allan at sindelarsolar.com
Fri Dec 16 12:15:43 PST 2022

I also found Kirk's response to capture what I would've checked first. 
Ray is correct about multiple neutral-ground bonds, but there's a point 
that I think has been missed. You didn't identify the generator, and I'm 
going to assume that it's a portable gasoline unit. They have GFCIs on 
the AC output because they're almost never connected to a solid ground, 
and that's the safest they can make the output - they internally bond 
neutral to the chassis of the gennie and run the output through a GFCI. 
When they're connected to an off grid home there's always going to be a 
ground loop in a correctly wired installation, because the Powercenter 
is the first point of disconnect and is thus where the overall system 
neutral-ground bond should be made.

In my experience there is no fully Code-compliant solution to this. At 
least, I never came up with one, and many years ago neither could John 
Wiles when I discussed it with him. You don't want to disconnect the 
bond in the E-Panel because if the gennie is the only bond point and 
it's disconnected (by unplugging it) your system ground becomes 
unbonded. Stationary generators generally separate the bond, or at least 
allow it to be separated (small Kohler units always allowed this), 
because of this very issue - for prime power (non-solar) applications 
the bond is made at the source, but where it's a secondary source it 
needs to be separated. Portable generators don't give this option.

The best solution John and I came up with is to treat the gennie as a 
separately derived system: ground it to its own rod; put it far enough 
from the home that you can't touch it and anything grounded in the home 
at the same time; bond normally in the E-Panel; and eliminate or 
disconnect and tie off the bonding conductor between the gennie and the 
PV system. Only by treating it as a separately derived system can you 
get around the requirement that all service equipment must be bonded.

And if the gennie has a separable neutral-ground bond that's been 
opened, I have no idea how to solve your issue... 😉
*Allan Sindelar*
allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
(Former) NABCEP Certified PV Installation Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
Founder (Retired), Sindelar Solar
*505 780-2738 cell*

On 12/16/2022 12:44 PM, Ray Walters via RE-wrenches wrote:
> Undoing the N-G bond at the E panel may not do it either.  Are you 
> sure neutral isn't also bonded in the main distribution panel?  It 
> usually is bonded at the generator, so you definitely have to unbond 
> there.  I'd say 60 to 70% of off grid systems are not bonded correctly 
> that I've seen.  Just what Kirk said: it should only be bonded N-G at 
> one and only one spot.  Check sub panels too.  My record was seven N-G 
> bonds on one site.  It caused the shower to be energized; the customer 
> thought that was normal....(don't touch the shower head!?!).....That 
> site even had a N-G bond in the well pump wiring!  Took 3 days of 
> unF***ing that wiring to finally get it.
> It ain't safe, until it's right.  The GFCI is doing its job, and so is 
> the Magnum.  Now the electrician has to do his job. Unless you wired 
> the whole house, you're On to fix it. Especially off grid, I see an 
> amazing bunch of DIY garbage. Find out who did the original wiring.  
> Probably not a pro.
> Ray Walters
> Remote Solar
> On 12/16/2022 11:35 AM, Kirk Herander via RE-wrenches wrote:
>> You may have neutral and ground connected at more than 1 location, 
>> meaning at the genset and in house panel, which means the ground is 
>> carrying current back to the generator in parallel with the neutral.
>> I remember with some Honda portables we had to float the neutral at 
>> the genset or the inverter would trip the generator's GFI when trying 
>> to charge the batteries.
>> On Fri, Dec 16, 2022 at 1:16 PM Dave Angelini Offgrid Solar via 
>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>     The easy answer is try another genset ! You have to be more
>>     specific, did it ever work? Is it new? etc. Good Luck !
>>     *Dave Angelini Offgrid Solar "we go where powerlines don't"
>>     http://members.sti.net/offgridsolar/ e-mail offgridsolar at sti.net
>>     text 209 813 0060*
>>     On 2022-12-16 10:04 am, Chris Daum via RE-wrenches wrote:
>>>     Hi folks:
>>>     We have a new Magnum MS4024 mounted on an E-Panel using a
>>>     MidNite Classic 150 and Whiz-Bang JR with power coming from an
>>>     array of Trina TSM365-De06X-05(II) (three strings of three) with
>>>     the ME-RC50 and a HUP SolarOne 6-85-14/24 battery.
>>>     When we attempt to use the PFC (Power Factored Charger), the Gen
>>>     Set’s GFCI outlets trip.  Thus far we have verified the
>>>     connections are secure, assured that the gen set is grounded,
>>>     disconnected the jumper within the E-Panel between the ground
>>>     buss and neutral, checked AC voltages, removed the MNSPD’s from
>>>     the buss(s)…  Stumped now on what an appropriate next step
>>>     should be.  How do we get the PFC to function properly?  What
>>>     are we missing?
>>>     Best,
>>>     Chris Daum
>>>     Oasis Montana Inc.
>>>     406-777-4309 or 4321
>>>     406-777-4309 fax
>>>     www.oasismontana.com <http://www.oasismontana.com>
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>> -- 
>> *Kirk Herander / **kirkh at vermont.solar*
>> *Owner|Principal, VT Solar, LLC*
>> */Celebrating our 31^st  Anniversary 1991-2022!!/*
>> *www.vermont.solar* 
>> <https://nam02.safelinks.protection.outlook.com/?url=www.vermontsolarnow.com&data=02%7C01%7C%7C9f0330d75a244870112408d685311841%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636842843233477645&sdata=0NjyuKeQbEK6245SNnk8X4XnP9Q%2B%2BqtvcALkdDghvk4%3D&reserved=0>
>> dba Vermont Solar Engineering
>> 802.863.1202
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