Threadless Rigid Coupling in Class I Div II Location - Concrete Encasement

[cwilkes]

We recently had an install of GRC conduit running underground into a Class I Div II aircraft hangar. During the course of construction the conduits were inadvertently cut off close to the curb level, approx 8" AFF. This caused the need for couplings to be within the first 18" of the Class I Div II location. Considering that the conduits were to close to the ground to now thread, we used GRC compression couplings under the mis-interpretation of 501.10B(4) Boxes & Fittings where it states fittings do not have to be explosion proof. Obviously, threadless couplings are not explosion proof.

Considering that the conduits are to short to thread, we asked the inspector if we could simply concrete encase them under 2" of concrete where they leave the floor. According to 230.6 (2)

230.6 Conductors Considered Outside of the Building

• 230.6(2) Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 2in thick.

I am aware that section 230 covers services and service conductors, however, does this rule apply to wiring methods in general? Does concrete encasement within a Class I Div II location isolate the coupling/conduit from that location? The inspector stated that since the pipes are within the envelope of the hazardous location, it wouldn't matter how much concrete we used, the compression couplings still wouldn't be allowed. We are attempting to avoid cutting concrete to make these repairs code compliant.

 

[masterinbama]

What size conduits are these?

 

[cwilkes]

(2) 3/4", (4) 1", (1) 2"

 

[masterinbama]

If you have 8" of pipe take a hickey bender and bend them one at a time to make room for your threading die. Or if you are real patient you can flip the teeth over in your dies and thread them that way.

 

[cwilkes]

In addition, isn't this a grayish area, where an approved wiring method is considered rigid threaded conduit, however, there is no need for explosion proof fittings. Aren't fully threaded couplings explosion proof? I know that 501.10B(4) is more geared towards fittings at boxes or enclosures (ie. simply running threaded conduit into a box using only locknuts to secure); however, the rule doesn't clarify this clearly. If I am not required to use explosion proof fittings, why would it have to be threaded?

Also, we come back to the 2" of coverage. If my GRC is covered with concrete anywhere within the boundary am I not considered outside of the boundary?

 

[cwilkes]

If you have 8" of pipe take a hickey bender and bend them one at a time to make room for your threading die. Or if you are real patient you can flip the teeth over in your dies and thread them that way.

Unfortunantly we do not have the 8". Most of the 8" is the curb the GC poured. We have maybe 1.5" to 2"

 

[GoldDigger]

Unfortunantly we do not have the 8". Most of the 8" is the curb the GC poured. We have maybe 1.5" to 2"

Demo some of the curb as needed and have the GC repair it?

 

[cwilkes]

Demo some of the curb as needed and have the GC repair it?

Thanks for your response GD. We are currently working our options, however, my post questions are geared more toward understanding the relevance of articles 230.6 and 501.10B(4) in this situation rather than the physical labor involved in the repair. As it sits now, we have few physical options.

 

[GoldDigger]

Thanks for your response GD. We are currently working our options, however, my post questions are geared more toward understanding the relevance of articles 230.6 and 501.10B(4) in this situation rather than the physical labor involved in the repair. As it sits now, we have few physical options.

You did not say where the eventual termination of the stubs will be, although it sounds like you intend for them to end up outside the building or at least the classified area. If you pour concrete over both the coupling and the rest of the conduit all the way to the boundary, I would say they have never entered the area. Whether the coupling under concrete is also OK if you then switch to a vapor tight or explosion proof (as appropriate) method of connecting the rest of the way without concrete over it might be harder to convince the AHJ about, but it is consistent with my reading of the rules.

 

[rbalex]

Electrical area classification is sometimes something ofart as well as a science. ?Moving? a boundary by introducing a physical barrieris usually acceptable. Especially in Division 2, I?d have no problem if thecoupling were fully imbedded.