Direct Burial Cable suitable for Haz Loc.

[MEP Guy]

When direct burial cable is suitable to haz locations, how is transition from an underground hazardous loacation made to an aboveground non-haz ?

Is it permissible to sleeve the last, say 2' on u/g cable in RMC and provide a xp seal off inside the non haz area ? Would a splice box be required to seal the u/g end ?

Any help / thoughts are appreciated.

 

[weressl]

When direct burial cable is suitable to haz locations, how is transition from an underground hazardous loacation made to an aboveground non-haz ?

Is it permissible to sleeve the last, say 2' on u/g cable in RMC and provide a xp seal off inside the non haz area ? Would a splice box be required to seal the u/g end ?

Any help / thoughts are appreciated.

This, again like other questions related to area classification, can not be answered without a drawing that shows the extent of the Division 1 and Division 2 areas.

 

[rbalex]

The critical element here is the cable construction. It is very likely no sleeve is necessary.

 

[hardworkingstiff]

I didn't know direct burial cable was a suitable wiring method for a classified location.

 

[rbalex]

It isn't common in the US, but it isn't prohibited. It is the dominant practice in IEC installations.

If the cable emerges to Division 1 above grade, it must be MC-HL that is also suitable for direct burial. It must be sealed at the first terminus. See Section 501.15(D)(1). MI and ITC-HL would also be acceptable. See 501.10(A)(1)(b), (c) & (d). All three constructions must have “suitable” underground protection. This does not necessarily mean raceway. See Sections 330.12, 332.12 and 727.4(8). Read the whole rule of all of the Sections carefully; they can be a bit misleading. Note also many Type MV constructions are MV/MC-HL

Division 2 provides a few more options if the cable is suitable for direct burial; adding Types PLTC, TC and MV to the mix. The concepts are similar. The subtle difference is that the cable may not need to be sealed except as required by Section 501.15(E)(1). All of the acceptable cable Types are UL recognized as having “… a gas/vaportight continuous sheath …” and are thus installed per 501.15(E)(3).

NOTE: None of the methods require a “boundary seal” at grade.

 

[rbalex]

I just realized I made an error with my response in respect to Division 2.

While MC-HL and ITC-HL are the only constructions acceptable in Division 1, they are not the only Type MC and ITC constructions acceptable in Division 2. This can be a problem since the “interlocked metal tape” forms of each of them would need to be installed per 501.15(E)(4). This construction DOES require boundary seals.

EDIT ADD: The “interlocked metal tape” forms are similar to Canadian "TECK" type cables which has been acceptable in Canada for Zone 1 and Division 1 as well as Zone 2 and Division 2 for a long time. This construction is not recognized in the US unless it is also classified as Type MC. Not all manufacturers’ products are so recognized.