[SML] Was Torqueing truss, Now Grounding Truss

[mouse at fieldmousepro.com]

Toothed washers sound like a solution in search of a problem. If there 
is any doubt about the grounding path, a simple resistance test between 
the truss and ground should reveal any issues. The only place I can 
think of where a toothed washer might come in handy is for truss that is 
painted and doesn't have a bare metal surface which would normally bond 
the various pieces together, as well as for a connection point intended 
to electrically ground the structure. Here's another thing: Any piece of 
gear with a grounded chassis will also ground the truss it's mounted to, 
assuming there's a bare metal connection between the two.

I'm not a structural engineer, but for what it's worth, I doubt that a 
toothed washer would significantly impact the load handling ability of 
the end plate of a piece of truss. Those are pretty thick slabs of 
metal, and the deformation would seem to be pretty shallow. Am I missing 
something in your description?

As for Noalox, it helps to prevent aluminum electrical connections from 
oxidizing, not because the connection wouldn't work at all without it, 
but to prevent overheating on current carrying connections due to the 
slight added resistance that the oxide would create. I would argue that 
its usefulness on grounding contacts is more of a "why not; it's cheap 
insurance" than a distinct need to ensure functionality.

Stephen

On 2024-03-23 9:16 pm, Joe Golden via Stagecraft wrote:

> Not to totally hijack Joel's query about torqueing truss, but I was 
> recently asked about adding "dragontooth" washers to truss bolts to 
> ensure that there was a "proper" ground path for ground supported 
> structures. This also doesn't bring into play the dissimilar metals and 
> needing to use NolOx or something similar at each bolt.
> 
> I checked ANSI E1.21 and the only mention of grounding was to clean the 
> tube with steel wool before applying the ground clamp.
> 
> Does anyone have any other citations not to use these washers. I am 
> against it do to excessive wear of the bolt plates.
> Joe Golden
> 
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