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

Drake drake.chamberlin at redwoodalliance.org
Wed Jan 16 06:50:37 PST 2013


That is an interesting point.  The Code issue is one of definition, 
not of function or safety.

At 04:02 PM 1/15/2013, you wrote:
>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: 
>><mailto:re-wrenches-bounces at lists.re-wrenches.org>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: 
>><mailto:re-wrenches-bounces at lists.re-wrenches.org>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>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/>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: 
>><mailto:re-wrenches-bounces at lists.re-wrenches.org>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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