Grounding of ridgid Conduits entering building from ha

[mr21]

Should conduits between seal off and metal raceway be EMT or ridgid and how should they be grounded or bonded.This pertains to gas stations/conveinence store's. Where the high and low voltage conduits enter the building before the electrical trough there are seal offs. Above the seal off is a nipple that goes into the trough, the statement posed by an inspector is that those nipples cannot be EMT, they must be ridgid and they must be individually grounded with seperate grounding clamps and connection to each conduit.

[ September 21, 2005, 04:18 PM: Message edited by: mr21 ]

 

[rbalex]

Re: Grounding of ridgid Conduits entering building from ha

I'm sorry, but your description is confusing; please redescribe.

 

[LarryFine]

Re: Grounding of ridgid Conduits entering building from ha

I understood the question, but I don't know the answer.

In a gas station, the conduits feeding the pumps emerge in the building under a trough. Seal-offs are installed on top of the stub-ups, and nipples are installed between the seal-offs and the trough.

The questions are:

1) May these nipples be EMT, or must they be the same type of conduit as the underground conduits?

2) Must each of these EMT or conduit nipples be individually bonded without dependency on fittings and/or locknuts in contact with the trough?

Mr 21, am I correct?

 

[dillon3c]

Re: Grounding of ridgid Conduits entering building from ha

Originally posted by mr21:
Above the seal off is a nipple that goes into the trough, the statement posed by an inspector is that those nipples cannot be EMT, they must be ridgid and they must be individually grounded with seperate grounding clamps and connection to each conduit.

IMO..Your Inspector is 50% right..
501.30(A)Bonding
The locknut-bushing and double-locknut types of contact shall not be depended on for bonding purposes,but bonding jumpers with proper fittings or other approved means of bonding shall be used.Such means of bonding shall apply to all intervening raceways,fittings,boxes,enclosures and so forth between the Class I locations and the point of grounding for the service equipment or point of grounding of the separately derived system.

501.15(B)(2)Class I Division 2 Boundary.

*-Ridged metal conduit or threaded steel intermediate metal conduit shall be used between the seal fitting -and the point at which the conduit leaves the Division 2 Location- *[/I] and a threaded connection shall be used at the seal fitting.Except for listed reducers @ the conduit seal,there shall be no union,coupling,box or fitting *between the conduit and the point @ which the conduit leaves the Division 2 Location*.

*What this is telling me,if your sealing fitting leaving the classified area,is installed in the conduit system outside of the boundary,of the classified area, and sealed with the approved methods to prevent the passage of gasses and vapors,your wiring method is fine,providing you comply with 501.30(A)..

It's not telling me,that threaded raceway must be used, beyond the seal fitting,and outside the Classified area of boundary..

Adding :mr21,
Also noting in your posting, you may have differant classifications of voltages,entering this same trough or wireway,as maybe defined in Article 504 or Article 725..(*if so please read the associated articles if needed) If so be sure to maintain a separation I] of the differant classes, by means of divider(effective separation) in this enclosure if needed.

[ September 22, 2005, 09:36 AM: Message edited by: dillon3c ]