Busway Systems - Siemens

14BUSWAYSYSTEMSBusway SystemsNational Electric CodeWhere a separate equipment groundingconductor is used, connection of theequipment grounding conductor to thebusway shall comply with 250.8 and250.12.(B) Cord and Cable Assemblies.Suitable cord and cable assembliesapproved for extra-hard usage and hardusage, and listed bus drop cable shall bepermitted as branches from the buswayfor the connection of portable equipmentor the connection of stationaryequipment to facilitate their interchangein accordance with 400.7 and 400.8 andthe following conditions:(1) The cord or cable shall be attached tothe building by the approved means.(2) The length of the cord or cable forma busway plug-in device to a suitabletension take-up support device shall notexceed 1.8 m (6 ft.).(3) The cord and cable shall not beinstalled as a vertical riser from thetension take-up support device to theequipment served.(4) Strain relief cable grips shall beprovided for the cord or cable at thebusway plug-in device and equipmentterminations.Exception to (B)(2): In industrialestablishments only, where theconditions of maintenance andsupervision ensure that only qualifiedpersons service the installation, lengthsexceeding 1.8 m (6 ft.) shall bepermitted between the busway plug-indevice and the tension take-up supportdevice where the cord or cable issupported at intervals not exceeding2.5 m (8 ft.).(C) Branches from Trolley-TypeBusways. Suitable cord and cableassemblies approved for extra-hard sageor hard-usage and listed bus drop cableshall be permitted as branches fromtrolley-type busways for the connectionof moveable equipment in accordancewith 400.7 and 400.8.368.58 Dead Ends. A dead end of abusway shall be closed.368.60 Grounding. Busway shall begrounded.III. Construction368.120 Marking. Busway shall bemarked with the voltage and currentrating for which they are designed andwith the manufacturers name ortrademark in such a manner as to bevisible after installation.IV. Requirements for over 600 Volts,Nominal368.214 Adjacent and SupportingStructures. Metal enclosed buswaysshall be installed so that temperaturerise from induced circulating currents inany adjacent metallic parts will not behazardous to personnel or constitute afire hazard.368.234 Barriers and Seals.(A) Vapor Seals. Busway runs that havesections located inside and outside of abuilding shall have a vapor seal at thebuilding wall to prevent interchange ofair between indoor and outdoor sections.Exception: Vapor seals shall not berequired in forced-cooled bus.(B) Fire Barriers. Fire barriers shall beprovided where fire walls, floors andceilings are penetrated.FPN: See 300.21 for informationconcerning the spread of fire or productsof combustion.368.236 Drain Facilities. Drain plugs,filter drains or similar methods shall beprovided to remove condensed moisturefrom low points on a busway run.368.237 Ventilated Bus Enclosures.Ventilated busway enclosures shall beinstalled in accordance with Article 110,Part III and 490.24.368.238 Terminations andConnections. Where bus enclosuresterminate at machines cooled byflammable gas, seal-off bushings, bafflesor other means shall be provided toprevent accumulation of flammable gasin the busway enclosures. All conductortermination and connection hardwareshall be accessible for installation,connection and maintenance.368.239 Switches. Switching devices ordisconnecting links provided in thebusway run shall have the samemomentary rating as the busway.Disconnecting links shall be plainlymarked to be removable only when thebus is de-energized. Switching devicesthat are not load-break shall beinterlocked to prevent operation underload and disconnecting link enclosuresshall be interlocked to prevent access toenergized parts.368.240 Wiring 600 Volts or Less,Nominal. Secondary control devices andwiring that are provided as part of themetal-enclosed bus run shall beinsulated by fire-retardant barriers fromall primary circuit elements with theTechnicalexception of short lengths of wire, suchas at instrument transformer terminals.368.244 Expansion Fittings. Flexible orexpansion connections shall be providedin long, straight runs of bus to allow fortemperature expansion or contraction orwhere the busway run crosses thebuilding vibration insulation joints.368.258 Neutral. Neutral bus, whererequired shall be sized to carry all neutralload current, including harmonic currentsand shall have adequate momentary andshort circuit rating consistent withsystem requirements.368.260 Grounding. Metal-enclosedbusway shall be grounded.368.320 Marking. Each busway runshall be provided with a permanentnameplate on which the followinginformation shall be provided:(1) Rated voltage.(2) Rated continuous current; if bus isforced-cooled, both the normal forcedcooledrating and the self-cooled (notforced-cooled) rating for the sametemperature rise shall be given.(3) Rated frequency.(4) Rated impulse withstand voltage.(5) Rated 60Hz withstand voltage (dry).(6) Rated momentary current.(7) Manufacturers name or trademark.FPN: See ANSI C37.23-1987(R1991),Guide for Metal enclosed Bus andCalculating Losses in Isolated-PhaseBus, for construction and testingrequirements for metal enclosed bus.14-20Siemens Power Distribution & Control, SPEEDFAX 2007-2008 Product Catalog