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

Brian Wiley btwinfinity at gmail.com
Tue Jan 15 13:02:18 PST 2013


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] 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] 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] 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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