T&B Conduit Fittings

Specifications—Rigid Metal Conduit/PVC Coated Rigid Metal ConduitT&B Conduit FittingsRigid Metal Conduit FittingsRef. CEC Rule 12-1000Rigid Metal Conduit affords maximummechanical protection to conductorswithin the raceway. Rigid metal conduitcan be installed indoors and outdoors, indry locations or wet locations, exposed orconcealed, in all atmospheric conditionsand in hazardous locations.Galvanized rigid steel conduitinstalled in concrete does not requiresupplementary corrosion protection.Galvanized rigid steel conduit, installed incontact with soil, does not generallyrequire supplementary corrosionprotection. However, when buried incorrosive soil (corrosive soil ischaracterized by low resistivity of lessthan 2,000 ohm-centimeter) or cinders, aprotective coating of bitumastic, asphaltbasedpaint or a PVC coating is appliedto the conduit. CEC Rule 12-934requires that rigid steel conduit installed inor under permanently moist cinder fill beencased in at least two inches ofcinder-free concrete unless the conduit isat least 18 inches below the fill. Steelconduit protected from corrosion solely byenamel can only be used indoors and inoccupancies not subjected to severecorrosive influences.Rigid nonferrous metal conduit(aluminum) cannot be directlyembedded in concrete containingsoluble chlorides such as calciumchloride; unwashed beach sand,seawater, or coral bearing aggregates.However, if adequately treated by aprotective coating of bitumastic orasphalt-based paint or PVC coating, theconduit can be installed in concretecontaining chlorides.Supplementary nonmetallic coatingspresently used on ferrous rigid metal ornonferrous metal have not beeninvestigated for resistance to corrosion.CEC Rule 12-920 requires that whenconduit enters a box or fitting, a bushingmust be provided to protect wires fromabrasion unless the design of the box orfitting provides equivalent protection.According to CEC Rule 12-906where No. 4 or larger ungroundedconductors enter or leave a conduit, aninsulating bushing with a smooth wellrounded insulating surface must beprovided to protect conductors unlessthe terminating fitting is equipped with aninsulated throat, firmly secured in placeproviding equivalent protection. Theinsulating bushing or insulating materialmust have a temperature rating of not lessthan the insulation temperature rating ofinstalled conductors. When conduitbushings are constructed wholly ofinsulating material, a locknut must beinstalled both inside and outside of theenclosure to which the conduit isattached.Fittings and couplings are requiredto be of concrete-tight type whenembedded in masonry or concrete or indry locations and of the raintight typewhen installed in wet locations.In wet locations or locationswhere walls are frequently washed orwhere there are surfaces of absorbentmaterials, the entire wiring systemincluding boxes, fittings, conduit andcables must be supported suchthat there is at least 1/4 inch air spacebetween it and the supporting surface(CEC Rule 2-122).CEC Rule 12-3024 requires that theraceways be metallically joined togetherinto a continuous electric conductorand must be mechanically connected toall boxes, fittings and cabinets as toprovide effective electrical continuity.Conduit is required to be supportedadequately and conduit bends inone run are restricted to the equivalentof four quarter i.e. 360 degrees total.Listed below are some of theadvantages of rigid aluminum conduitover rigid steel conduit.1. Non-sparking—eliminates hazard inexplosive atmospheres2. Non-magnetic—reduces power lossdue to voltage drop3. Resists most corrosive atmospheresand industrial environments4. Lightweight—reduces costof handling and installation5. Attractive appearance5