[RE-wrenches] Module grounding requirements

[Drake Chamberlin]

Hello Wrenches,

Where is the requirement that states that modules need to be grounded 
by means of Weeb clips, or grounded by wires connected to the 
modules?  Reviewing the code, I can't find the requirement in Section in 690.

If the issue is that the anodized aluminum frame can build up a 
coating, therefore must have additional grounding that penetrates 
that coating, it seems that star washers should be effective.   In a 
typical setup, a lug might be bolted to a module, with a star washer 
between the frame and the lug.  How is this going to be more 
effective than having two modules bolted together with a star washer between?

Is this a UL requirement?

Thanks,

Drake

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648