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

Wed Jan 16 09:22:21 PST 2013

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

*From:* 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
<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
<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
<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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