Metal components used with non-metal raceway systems.

[rbalex]

Situation:

Moderately severe corrosive atmosphere; materials used have been properly validated/certified for the application.

Raceway is listed Type RTRC, fiberglass.(Article 355 ? 2008 NEC). Pull boxes are listed Type 4X, all fiberglass construction with the following exceptions: cover hinge, door latches, and their attachment hardware are stainless steel. Manufacturer supplied locknuts for securing raceways to enclosures are also stainless steel. Support steel and ancillary metal hardware is stainless with some non-metal spacers.

Electrical distribution system is medium voltage, impedance grounded. Properly sized equipment grounding conductors are installed in each raceway and terminated properly at the source and utilization equipment.

Question:

In light of Section 250.4(A)(1)-(5), which, if any of the stainless items need to be grounded/bonded?

Feel free to cite any other relevant Sections.

 

[chris kennedy]

This appears to be your scenario.

250.4 General Requirements for Grounding and Bonding.

(4) Bonding of Electrically Conductive Materials and Other Equipment.

Normally non?current-carrying electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.

Do you believe the highlighted area above is 'likely' to occur?

 

[don_resqcapt19]

Chris,
I think the relevant sections for this would be 250.4(A)(2) and (3) not 250.4(A)(4). (2) and (3) do not use the words "likely to become energized".
I think you can make a strong case that the locknut must be bonded, but not a good case for the other items. However I think that you can make a case that 250.190 requires all of the items to be bonded/grounded.

 

[rbalex]

Thanks for the responses.

Don pretty much made the same case I have (the locknut definitely - the others maybe, but probably not). I wanted "another set of eyes" and anyone else who feels they would like to comment - feel free.

Bonding the locknut is a real pain because this stainless and copper don't like each other too much. I may go for a "special permission" exception. The locknuts aren't exposed and, if they ever became energized, they wouldn't increase the hazard beyond what was already a bad situation.

I'm iffy on 250.190; most folks would agree the Exception applies. It's hard to approach this installation; hell, it's hard enough to just get in and install it. I'd give more info if I were allowed. It isn't "Top Secret," but it is highly confidential at the moment.