4 Mar 11 14:53
I have several automatic shutoff valve assemblies (see example below)which have both a solenoid and a proof of closure limit switch, both of which are rated for a class 1 div 2 application. In a non hazardous environment we would typically run a short peice of liquid-tight flexible conduit from the solenoid to the switch and then bring a single cable back from the switch to my cabinet. However, in my experience this type of polymer coated conduit is not allowed for this hazardous location. Either rigid or at flexible metal conduit with an outer metal braid is required. I have not been able to find a flexible conduit which carries a class 1 div 2 rating, and I would prefer not to use rigid. Has anyone run into a similar problem or have any suggestions?
The NEC 70 section which covers this is as follows:
(B) Class I, Division 2.
(1) General. In Class I, Division 2 locations, the following wiring methods shall be permitted:
(1) All wiring methods permitted in Article 501.4(A).
(2) Threaded rigid metal conduit, threaded steel intermediate metal conduit.
(3) Enclosed gasketed busways, enclosed gasketed wireways.
(4) Type PLTC cable in accordance with the provisions of Article 725, or in cable tray systems. PLTC shall be installed in a manner to avoid tensile stress at the termination fittings.
(5) Type ITC cable in cable trays, in raceways, supported by messenger wire, afforded mechanical protection and run as open wiring, or directly buried where the cable is listed for this use.
(6) Type MI, MC, MV, or TC cable with termination fittings, or in cable tray systems and installed in a manner to avoid tensile stress at the termination fittings.
(2) Flexible Connections. Where provision must be made for limited flexibility, flexible metal fittings, flexible metal conduit with listed fittings, liquidtight flexible metal conduit with listed fittings, liquidtight flexible nonmetallic conduit with listed fittings, or flexible cord listed for extra-hard usage and provided with listed bushed fittings shall be used. An additional conductor for grounding shall be included in the flexible cord.
FPN: See 501.16(B) for grounding requirements where flexible conduit is used.