Rules for grounding bonding 24vdc

[sgreene]

I have a project that the AHJ has told my engineer he wants all of our 24vdc j-boxes(containing only I/O cards and Ethernet) to be bondes to the structure itself. The boxes are all plastic w/ metal back plates. He insisted they be bonded to the structure and did not want them individually grounded back at the main control panel. This particular project will be installed in Clark County Nevada. Does anyone have any insight as to why we need to bond plastic boxes to the structure, and being low voltage is it required to even bond these boxes as per NEC. References would be great! :angel:

 

[petersonra]

You can't bond plastic, so I suspect you are not describing accurately exactly what is being asked for.

I also doubt that the "ahj" is involved in this. more likely just an inspector.

I would let the engineer work it out with whoever he is dealing with. That is part of his job.

 

[steve66]

I would assume its the metal back plates he wants bonded.

It might be coming from the article that says something like "metal piping systems, ducts, and other systems likely to become energized shall be grounded." Not sure what article that is.

Short pieces of wire to the structure are probably less likely to be damaged or disconnected than homeruns to the main control panel, and a quick visual inspection is all it takes to verify the bonding.