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Hi Brian,<br><br>
Very good points. In function, the frames of the modules and the
aluminum racking are grounding bus bars that are connected together with
bolts and rivets (Weebs). This method is allowed by 250-64 C
2. All that is required is for inspectors / code writers to
acknowledge that the frames and rails fit this definition. It may
require additional wording or an exception. <br><br>
This is not an issue of safety, function or science, but one of
semantics. <br><br>
Drake <br><br>
<br><br>
At 05:31 PM 1/17/2013, you wrote:<br>
<blockquote type=cite class=cite cite="">Hi John,<br><br>
You have brought up several points.<br><br>
1. practical answer<br>
The NEC says that a GEC can be solid aluminum. PV mounting rails are
typically aluminum. It is easy to calculate the ampacity of a solid
aluminum piece from its cross-section.<br>
Even the lightest rails on the market have an ampacity that is an order
of magnitude greater than the copper wires required by code for
GECs.<br>
The 2011 NEC, section 250.64(C)(3) says that "Bolted, riveted or
welded connections of structural metal frames ... of structures" are
permitted splices for the GEC.<br>
The WEEB is a tested and characterized device and therefore preferable to
one that, while allowed by code, has not been characterized at
all.<br><br>
2. listing<br>
There is no standard to list equipment for use as a GEC or an EGC. The
lack of a standard does not mean equipment is not suitable, it just means
we need to use good engineering judgement until the codes catch up.<br>
Does new equipment meet the intent of the existing code? Are there any
valid engineering reasons not to use new equipment? I think those are the
questions we should focus on.<br>
Note that the WEEB was introduced almost 7 years ago and these code
issues still have not been resolved to everyone's satisfaction.<br><br>
3. connecting to a copper wire<br>
Jason Szumlanski discussed this already, but I will reiterate. When you
connect a GEC to a string inverter it is done in a reversible manner,
typical with a screw connection. When you connect to a PV system,
consisting of multiple distributed inverters, you can do so with a
reversible connection, typically a listed lug, anywhere on the PV
system.<br><br>
Best Regards,<br>
Brian Wiley<br><br>
<br><br>
On 1/17/2013 10:58 AM, John Berdner wrote:<br>
<blockquote type=cite class=cite cite="">Jay:<br>
<br>
You raise an interesting question.<br>
<br>
I believe the structure would have to be evaluated and Listed for
equipment grounding (UL is working on a new Standard for this now) AND
for use as a GEC (which I don’t think is possible). <br>
Even if the WEEB was approved for use as a GEC (I still do not feel this
is the case) the rail then needs to be contiguous or irreversibly spliced
to the copper GEC.<br>
I am not aware of any Listed hardware that facilitates this. <br>
Anyone know of any ?<br>
<br>
We also have a dissimilar metals problem irreversibly crimping or
exothermic welding (the Code requirement) copper to aluminum.<br>
<br>
Best Regards,<br>
<br>
John Berdner<br>
General Manager, North America<br>
<br><br>
<br>
Solaredge Technologies, Inc.<br>
3347 Gateway Boulevard, Fremont CA 94538 USA <b><i>(*Please note of
our new address.)</i></b><br>
T: 510.498.3201 ext 747<br>
M: 530.277.4894 <br>
<br>
<b>From:</b>
<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">
re-wrenches-bounces@lists.re-wrenches.org</a>
[<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" eudora="autourl">
mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of
</b>jay peltz<br>
<b>Sent:</b> Wednesday, January 16, 2013 8:52 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] GEC for Micro-Inverters and ACPV
Modules<br>
<br>
Dear John and Brian<br>
<br>
Thanks for a great discussion. <br>
<br>
My question is:<br>
<br>
If you used a WEEB to connect the inverter to the rail, is the rack rail
listed as a GEC?<br>
Or does it have to be listed as a GEC?<br>
<br>
Thanks<br>
<br>
Jay<br>
<br>
Peltz power<br>
<br>
<br>
<br><br>
<br>
Sent from my iPad<br><br>
On Jan 16, 2013, at 12:09 PM, Brian Wiley
<<a href="mailto:btwinfinity@gmail.com">btwinfinity@gmail.com</a>>
wrote:<br>
<dl>
<dd>Hi John,<br>
<br>
<dd>I don't feel that you are argumentative. I am glad for this forum and
people to put forth honest opinions.<br><br>
<dd>I think you just may not be aware of how the WEEB actually works. It
is a type of rivet, not just a pronged thing that makes connection as
part of a bolted connection.<br><br>
<dd>It does use a bolt to engage the part, but the teeth on the WEEB are
specially shaped. When the bolt is torqued, the teeth deform, similarly
to a rivet.<br>
<dd>The metal that it is connecting to mushrooms up around the tooth and
the tooth pinches in around the metal.<br>
<dd>This deforming action is what forms an exceptional electrical
connection and also forms an air-tight seal between the part and embedded
metal to resist corrosion.<br><br>
<dd>If you remove the bolt, the WEEB will still be connected to the
metal. You must forcibly remove the WEEB from the metal.<br><br>
<dd>Hope that clears things up for you.<br><br>
<dd>Best Regards,<br>
<dd>Brian Wiley<br><br>
<br><br>
<dd> <br><br>
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