501.4.Wiring Methods. (B) Class I, Division 2 (Gases or Vapors). Types ITC, PLTC, MI, MC, MV, or TC cables may be installed in cable tray in this type of hazardous (classified) area. Under the conditions specified in Section 501.5(E), Cable seals are required in Class 1, Division 2 areas. Cable seals should be used only when absolutely necessary.
501.5.Sealing and Drainage. (E) Cable Seals, Class 1, Division 2. (1) Cables will be required to be sealed only where they enter certain types of enclosures used in Class 1, Division 2 areas. Factory sealed push buttons are an example of enclosures that do not require a cable seal at the entrance of the cable into the enclosure.
501.5.Sealing and Drainage. (E) Cable Seals, Class 1, Division 2. (2) Gas blocked cables are available from some cable manufacturers but they have not been widely used. For gas to pass through the jacketed multiconductor cable's core, a pressure differential must be maintained from one end of the cable to the other end or to the point where there is a break in the cable's jacket. The existence of such a condition is extremely rare and would require that one end of the cable be in a pressure vessel or a pressurized enclosure and the other end be exposed to the atmosphere. The migration of any significant volume of gas or vapor though the core of a multiconductor cable is very remote. This is one of the safety advantages that cable tray wiring systems have over conduit wiring systems. There are documented cases of industrial explosions caused by the migration of gases and vapors through conduits when they came in contact with an ignition source. There are no known cases of cables in cable tray wiring systems providing a path for gases or vapors to an ignition source which produced an industrial explosion.
501.5.Sealing and Drainage. (E) Cable Seals, Class 1, Division 2. (3)
Exception: Cables with an unbroken gas/vapor- tight continuous sheath shall be permitted to pass through a Class 1, Division 2 location without seals.
Cooper B-Line, Inc
This is an extremely important exception stating that cable seals are not required when a cable goes from an unclassified area through a classified area then back to an unclassified area.
501.5.Sealing and Drainage. (E) Cable Seals, Class 1, Division 2. (4)
If you do not have a
The sheaths mentioned above may be fabricated of metal or a nonmetallic material.
502.4.Wiring Methods. (A) Class II, Division 1 (Combustible Dusts). Type MI cable may be installed in cable tray in this type of hazardous (classified) area.
The Exception allows Type MC cables to be installed in Class II, Division 1 areas if they have a gas/vapor tight continuous corrugated aluminum sheath with a suitable plastic jacket over the sheath. They must also contain equipment grounding conductors sized as per Section 250.122 and listed termination fittings must be used where the cables enter equipment.
502.4.Wiring Methods. (B) Class II, Division 2 (Combustible Dusts).
This section states:
Type ITC and PLTC cables may be installed in ladder or ventilated cable trays following the same practices as used in
Type MC, MI and TC [See Section 336.4(3)] cables may be installed in ladder, ventilated trough, or ventilated cable channel, but they are not allowed to
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be installed in solid bottom cable trays.
Required Spacing in Cable Trays for Type MC, MI & TC Cables in Class II, Division 2 Hazardous (Classified) Areas
Cable Tray Manual
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