# Hazardous location cl1 div 2



## Sethj12 (Jul 19, 2019)

Im installing some conduits in a class 1 div 2 area. Im reading 501.15(B)(2) exception 4 and am confused by the word segment. Can anyone clarify the use of the word?


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## wildleg (Apr 12, 2009)

segment = portion. ie the portion(s) of the conduit system.


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## HertzHound (Jan 22, 2019)

If it helps, here’s the McGraw Hill explanation from the 2008 Hanbook. 


501.15 CLASS I LOCATIONS 1165
Exception No. 1 to part (B)(2) is worded the same as Exception No. 1 in part (A)(4) for Class I, Division 1 locations. Exception No. 1 to 501.15(B)(2) covers the case where a metal conduit system passes from a nonhazardous area, runs through a Class I, Division 2 hazardous area, and then returns to a nonhaz- ardous area. Such a run is permitted to pass through the hazardous area with- out the need for a seal fitting at either of the boundaries where it enters and leaves the hazardous area, provided that the conduit in the hazardous area does not contain unions, couplings, boxes, or fittings. In a Class I, Division 2 loca- tion, the same prohibition against unions, couplings, and so on, is applicable, and the method in Fig. 501-26 is not acceptable if seals are omitted at the boundary crossings. A seal would not be needed at A, B, C, or D, if the conduit passed through the Class I, Division 2 location without any coupling or other fittings in the conduit.
Exception No. 2 to part (B)(2) addresses installations where the conduit pass- ing from the Class I, Division 2 location into an unclassified location does not enter any enclosures that produce an arc or spark. Such an installation does not require a conduit seal, provided it is also installed outdoors, or if the conduit sys- tem is installed in a single room, it may be installed indoors. But in no case should the unsealed conduit be connected to any enclosure that contains a source of ignition. The outdoor locations work by abundant ventilation and the indoor locations because if all the wiring is in the same room, it is all at the same atmospheric pressure and will not transmit fumes.
Exception No. 3 recognizes that where an enclosure or room is unclassified because it is pressurized to prevent accumulation of an explosive concentra- tion, there is no need to seal the raceway where it leaves the Division 2 location and enters the pressurized spaces because the press will prevent gas from enter- ing that unclassified area.
Exception No. 4 eliminates sealing for those portions of the conduit system that satisfy all the conditions given in parts (1) to (5). The conditions, taken together, describe a conduit layout for which it would be impossible for fumes to enter the raceway to begin with.


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## Weasel (Jul 14, 2019)

Seth by definition of the NEC a class 1 division 2 area means under normal conditions there is no hazard. Class 1 division 1 area there is always a hazard


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## joebanana (Dec 21, 2010)

A segment of conduit is a stick, or a single piece. One part of a larger system. ie. a conduit between two boxes is a segment.


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## Sethj12 (Jul 19, 2019)

What i have are 2 scenerios:

1: conduits go from a control panel in an unclassified room, thru a wall, along a tank wall and thru the tank wall. distance from unclassified to classified appox 50 feet

2: conduits go from a man hole, up a rack and along a wall into classified area. distance from classified to ground approx 30 feet.

both class 1 div 2


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## varmit (Apr 19, 2009)

In either of your scenarios a seal (seal off) would be required at within 1 foot of the boundary of the classified area. The purpose being to limit transmission of flammable vapors/materials through the conduit to a possible ignition source.


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## Sethj12 (Jul 19, 2019)

Im sorry, i forgot to mention that the pipes are located outside in an unclassified area. The lengths i mentioned represent that


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