[RE-wrenches] GEC for Micro-Inverters and ACPV Modules

Mark Frye markf at berkeleysolar.com
Wed Jan 16 10:07:56 PST 2013


I believe the WEEB is a great product for producing equipment grounds. 
But for producing a GEC I don't see it. Even if I bond the inverter case 
to the rail with a WEEB what is the next step in the chain, a reversible 
WEEB lug to bond the rail to the wire. Still, I don't think the GEC for 
these microinverters is a rational requirement. It appears from the 
discussion that if I have a seperately installed microinverter that 
bonds it's DC side to ground, the Code requires a GEC but if I take that 
exact same inverter, assemble it to a module and test and list them as 
an AC module the requirement for GEC goes away. This is another 
indicator that the application of this requirement in the Code itself is 
specious.

Mark Frye

On 1/16/2013 9:53 AM, John Berdner wrote:
>
> Brain:
>
> Not trying to be argumentative here...
>
> I understand that you feel that a WEEB is equivalent to an 
> irreversibly spliced connection but, as most commonly used in the 
> field, I disagree.
>
> The Code does not recognize bolted connections of any kind  as 
> equivalent to irreversible spliced or contiguous.
>
> It is an issue of the type of connection not the presence of the WEEB 
> clip in that connection.
>
> For Example: If the WEEB connection was riveted in place then I 
> believe it would be considered irreversibly spliced but as part of a 
> bolted connection, no.
>
> With specific reference to GEC see 250.64C in the 2011 NEC or 2011 NEC 
> Handbook.
>
> Lastly, the argument that it is a similar level of difficult to 
> cutting the wire, while true, is not relevant to the Code requirement. 
>  Cutting a contiguous wire is also a similar level of difficulty to 
> opening a bolted connection but obviously a bolted connection is not a 
> contiguous wire.
>
> Best Regards,
>
> John Berdner
>
> General Manager, North America
>
> SmallBannerPictEngnew
>
> 3347 Gateway Boulevard, Fremont CA 94538 USA */(*Please note of our 
> new address.)/*
> T: 510.498.3201 ext 747
>
> M: 530.277.4894
>
> *From:*re-wrenches-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of 
> *August Goers
> *Sent:* Wednesday, January 16, 2013 9:22 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
> Thanks Brian. This has been a helpful thread for me. Mark Frye, thanks 
> for kicking it off.
>
> Best, August
>
> August Goers
>
> Luminalt Energy Corporation
>
> 1320 Potrero Avenue
>
> San Francisco, CA 94110
>
> m: 415.559.1525
>
> o: 415.641.4000
>
> august at luminalt.com <mailto:august at luminalt.com>
>
> *From:*re-wrenches-bounces at lists.re-wrenches.org 
> <mailto:re-wrenches-bounces at lists.re-wrenches.org> 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org 
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of 
> *Brian Wiley
> *Sent:* Tuesday, January 15, 2013 1:02 PM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
> Hi August,
>
> I maintain that the WEEB is an irreversible splice.
> If you want to disconnect a WEEB from a structure, you must 
> irreversibly damage the device. It cannot be reused.
>
> Admittedly the force required to remove a WEEB is less than that 
> required for a thermal splice, but it doesn't take much force to just 
> cut a wire either.
>
> I would argue that the intent of the code is to prevent inadvertent 
> removal of the ground. You must knowingly remove a WEEB from the 
> grounding path and if you do so in the maintenance of an array, good 
> workmanship requires that you restore the connection.
>
> Best Regards,
> Brian Wiley
>
> On 1/15/2013 2:11 PM, August Goers wrote:
>
>     Hi John,
>
>       
>
>     I definitely see your point and that is why I was somewhat questioning the
>
>     use of WEEBs with Enphase below. Enphases's instructions (link posted in
>
>     thread below) seem to indicate a support of running the continuous GEC on
>
>     the rack and then bonding the microinverter to the rack with WEEBs. Maybe
>
>     I am misinterpreting the document or perhaps Enphase has another take.
>
>     There is no question that according to NEC 250.64(C) the GEC must be
>
>     continuous. In the 2008 NEC handbook section 690.42 Point of System
>
>     Grounding Connection has an application note "Connections are to be made
>
>     in accordance with markings on the equipment or in the installation
>
>     instructions."
>
>       
>
>     All that said, it seems like technology is leaning towards listed AC
>
>     Modules or floating array inverters. It sounds like that removes the
>
>     requirement for a GEC which is great to help reduce installation costs.
>
>     The GEC has always been a pain in the neck.
>
>       
>
>     Best,
>
>       
>
>     August
>
>       
>
>       
>
>     -----Original Message-----
>
>     From:re-wrenches-bounces at lists.re-wrenches.org  <mailto:re-wrenches-bounces at lists.re-wrenches.org>
>
>     [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of John
>
>     Berdner
>
>     Sent: Monday, January 14, 2013 7:07 PM
>
>     To: RE-wrenches
>
>     Subject: Re: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
>       
>
>     August:
>
>       
>
>     The WEEB or other Listed grounding means between the inverter case and the
>
>     structure are not "contiguous or irreversible spliced" and therefore do
>
>     not meet the requirements for a GEC.
>
>     If the structure is then grounded via a bolt on lug it also is not
>
>     irreversible or contiguous.
>
>     If you can unbolt something and disconnect the ground then it is not
>
>     contiguous or irreversibly spliced.
>
>     Both of the above are ok for EGC but not for GEC.
>
>       
>
>     GEC is a pain in the neck but the Code requirements are clear.
>
>     If the PV array conductor (pos or neg) is bonded to ground by the inverter
>
>     then the inverter requires a GEC with all the related requirements - no if
>
>     and's or but's.
>
>       
>
>     Best Regards,
>
>       
>
>     John Berdner
>
>     General Manager, North America
>
>       
>
>     SolarEdge Technologies, Inc.
>
>     3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new
>
>     address.)
>
>     T: 510.498.3201 ext 747
>
>     M: 530.277.4894
>
>       
>
>       
>
>     -----Original Message-----
>
>     From:re-wrenches-bounces at lists.re-wrenches.org  <mailto:re-wrenches-bounces at lists.re-wrenches.org>
>
>     [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of August
>
>     Goers
>
>     Sent: Monday, January 14, 2013 4:32 PM
>
>     To: RE-wrenches
>
>     Subject: Re: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
>       
>
>     Hi Mark,
>
>       
>
>     There have been some recent threads on this list touching on this topic.
>
>       
>
>     As far as I understand, Enphase microinvertes still require a GEC up to
>
>     and including the 2011 NEC. I don't know about the 2014 NEC. Enphase bonds
>
>     the positive DC module conductor to ground. Pages 16 and 17 of their M215
>
>     installation manual address grounding:
>
>       
>
>     http://enphase.com/wp-uploads/enphase.com/2011/06/Enphase_M215_Installatio
>
>     nOperation_Manual.pdf
>
>       
>
>     Products such as Solar Bridge that are listed as Alternating Current (AC)
>
>     Modules (per NEC 690.2) don't need a Grounding Electrode Conductor (GEC)
>
>     as long as there are no conductors connected to ground within the product.
>
>     Solar Bridge has a good article on this:
>
>       
>
>     http://solarbridgetech.com/microinverters-and-ac-pv-modules-are-different/
>
>       
>
>     This all takes us back to using Enphase with grounding washers like WEEBs
>
>     for the GEC. According to what I read in their instructions (and after
>
>     many phone calls), it sounds like they are okay with us running the GEC on
>
>     the racking in #6 and then bonding the microinverters to the rack with
>
>     WEEBs. Seems a little strange but it's been working for us.
>
>       
>
>     Good topic!
>
>       
>
>     Best,
>
>       
>
>       
>
>     August
>
>     415.559.1525
>
>       
>
>       
>
>     -----Original Message-----
>
>     From:re-wrenches-bounces at lists.re-wrenches.org  <mailto:re-wrenches-bounces at lists.re-wrenches.org>
>
>     [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
>
>     Sent: Monday, January 14, 2013 3:31 PM
>
>     To: RE-wrenches
>
>     Subject: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
>       
>
>     Does anyone have the latest on the GEC for micro-inverters/ACPV issue?
>
>       
>
>     I know it is still in NEC 2008 and I believe 2011 with plans to address it
>
>     in 2014.
>
>       
>
>     I am specifically interested in the issue of GEC means continues
>
>     (irreversible splices) and the whole business of the DC side of these
>
>     devices constituting a separately derived system.
>
>       
>
>     Enphase technical support is fine if the micro inverter chasis is bonded
>
>     to a EGC only, but they leave the lug on the chasis if you want/need to
>
>     build a GEC.
>
>       
>
>     SolarBridge (pre-assembled micro-inverter) seems to be devoid of a chasis
>
>     lug and therefore by extension does not/can not had a GEC in the system.
>
>       
>
>     Exeltech (integrated micro-inverter aka. ACPV) does not seem to have a lug
>
>     on its chasis.
>
>       
>
>       
>
>     Has the industry pretty much moved to not requiring a GEC for these
>
>     devices and if so, how are the AHJ taking it?
>
>       
>
>     Thanks,
>
>     Mark Frye
>
>     Berkeley Solar Electric Systems
>
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