Grounding Issues

We recently installed a solar array using WEEB grounding clips from Wiley Electronics.  While these clips are ETL Listed. appear to have superior galvanic properties and far superior electrical characteristics, they were rejected by the inspector.

The Wiley WEEB grounding clip, shown below, grounds the module frame to the aluminum rails. 

The inspector wanted to use the GBL4-DBT lug.  

 Notice the Stainless steel screw used to hold the lug to the module frame.

There was no course of action but to tear the array down and install the copper wire preferred by this inspector.  An email to Wiley resulted in the following comments:

Hi Dennis,

I am sorry to hear about your inspection problems.  We are always trying to talk to these guys and educate them, but it is a difficult task. Sometimes allowing them to comment and buy into the design before installing helps.

If you do want to push the inspector a bit more, I would ask why he thinks the lug method is any better.  It is not code compliant for several reasons.  First with the lug, all the current must go through the stainless steel screw.  Stainless steel is not allowed as a conductor according to the code.  It would be possible to have the screw listed together with the lug to UL467, but to my knowledge no manufacturers have done so.  A subtle point here is that the manufacturer of the lug is not providing the screw, the distributor is.

Furthermore, our own lab tests have shown that if they have the lug/screw listed, it could only be used with a 10 AWG copper wire, nothing larger, because of the high resistance of stainless steel.  Note that the WEEB is able to carry much more current because it is very thin and in good thermal contact with a big chunk of aluminum.  Most inspectors require a 6 AWG and this is also a change to the 2008 NEC.  In general most of these inspectors are well intentioned, just not very technical and uninformed. 

With regard to your electrochemical comments, I am attaching a portion of proposed changes to UL1703 by UL.  The potential difference between stainless steel and aluminum is 0.55, while it is recommended that this be 0.6 or below.  Of course, the lug method also generally uses
stainless steel although since it is not listed you don’t really know what type of stainless steel.

We have a lot of info about the WEEB on our web site.  If you have any
further questions, please just let us know.

It appears that the inspector in this case was well intentioned but did not properly apply a little common sense, to the detriment of the solar customer.  

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