T&B Conduit Fittings

T&B Conduit FittingsRigid Metal Conduit FittingsSuggested Specifications for Rigid Metal Conduit/PVC Coated Rigid Metal Conduitand Fittings (continued)Series 140LocknutSeries 3210Knockout BushingSeries 222TBInsulating BushingSeries 3870Insulated Grounding &Bonding BussingSeries 1942Insulated NippleSeries 674Threaded CouplingSeries TRIB50Threadless RigidInsulating Bushing• Where concrete-tight requirementsmust be met, or in dry locations, rigidmetal conduit or intermediate metalconduit fittings and couplings shallbe of the concrete-tight type. Fittingsshall be rugged, of ferrous metalconstruction, electro-zinc platedinside and outside, and furnishedwith a nylon bushing asmanufactured by Thomas & Betts,series 8123 and 8120. Insulated setscrew type fittings such as Thomas &Betts series 8125 and 8124 may besubstituted unless otherwiseindicated on drawings.Components critical to performancesuch as set screws, split rings, andlocknuts shall be hardened oradequately designed to insurepositive bond between conduitand enclosure or conduit runs.All fittings of the system shall becapable of carrying ground faultcurrents per the following:1/2” through 1-1/2” size…10,000 ampsRMS (duration of fault current 3 cycles)2” and above…20,000 amps RMS(duration of fault current 3 cycles)• All back-to-back nippling of boxesshall be done using locknuts and nylonbushed nipples as manufactured byThomas & Betts, series 140 locknutsand series 1942 nipples. Nipples, orsuitably designed bushings such asThomas & Betts series 3210, shall alsobe used where conductors passthrough either factory or field punched,cut or drilled holes in metallicmembers.• Where neither length of threadedconduit can be rotated, couplingssuch as Thomas & Betts series 674shall be installed in conduit runs.• Where threaded or threadlessconduit terminates outside a boxor an enclosure, or where conduit isstubbed up, it shall be equipped withan insulated metallic or nonmetallicbushing such as Thomas & Betts series1222 or TRIB50.• Where code requires bonding andgrounding of single or multiple rigidmetal conduits or where positivebonding and grounding of conduit tothe box, enclosure or auxiliary gutteris required, the end of the conduitshall be equipped with an insulatedmetallic grounding and bondingbushing such as Thomas & Bettsseries 3870.Insulated metallic grounding andbonding bushing shall be approved forthe purpose. It shall be of malleableiron/steel construction adequatelyprotected against corrosion, assembledwith an insulator listed or certified for150°C/302°F application andflammability rating of 94V-0 withinsulator positively secured in place.Bonding to enclosure shall not bedependent on locknut bushing typecontact but by a positive bondingmeans such as a hardened screw orequivalent.9