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Application Guidelines for FMC

NEMA RV 3 Application & Installation Guidelines For Flexible & Liquid Tight Flexible Metal Conduits. Application Guidelines for FMC. Construction of FMC Grounding and Bonding Uses Permitted and Not Permitted. Construction for FMC. Constructed in accordance with NEC

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Application Guidelines for FMC

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  1. NEMA RV 3Application & Installation Guidelines For Flexible & Liquid Tight Flexible Metal Conduits www.nema.org

  2. Application Guidelines for FMC • Construction of FMC • Grounding and Bonding • Uses Permitted and Not Permitted www.nema.org

  3. Construction for FMC • Constructed in accordance with NEC • Complies with safety requirements of UL1 • Interlocked corrosion resistant steel or Aluminum strip www.nema.org

  4. Picture Example for FMC www.nema.org

  5. Diagram Example for FMC Cross-section view illustrating interlocking construction www.nema.org

  6. Grounding and Bonding for FMC • Permitted for bonding • When installed with listed fittings and; • Flexibility is not required after installation and; • When installed according to NEC Articles 348 and 250 and; • Protected by overcurrent device rated 20 Amperes or less. • Limited to 6’ lengths when used for bonding (see NEC 250.118 (5)) • Grounding conductor required if FMC • installed for flexible equipment or • when used in lengths greater than 6’. • Grounding and bonding continued in slide 7… www.nema.org

  7. Product Marking for FMC • Manufacturer’s designation • UL Logo • Conduit type • Reduced wall (RW) • Extra reduced wall (XRW) • Material type • Aluminum (AL) • Steel (No Mark Required) www.nema.org

  8. FMC Marking Example www.nema.org

  9. Uses Permitted for FMC • Exposed and concealed locations – NEC 348.10 • Dry locations only • Branch circuits and feeders • Ducts or plenums for environmental air • 300.22(B) limits to 4’ length • 300.22(C) no length limit • Under raised floors for computer rooms • Lighting whips and motor leads • These uses are not all inclusive, but serve as guidelines www.nema.org

  10. Uses Not Permitted for FMC • NEC 348.12 • Wet locations • 2008 NEC removed exceptions • Hoistways except as permitted in 620.21(A)(1) • Storage battery rooms www.nema.org

  11. Uses Not Permitted – cont. for FMC • Hazardous locations except 501.10(B) and 504.20 • Where conductors are exposed to deteriorating material • Underground or in concrete • Where subject to physical damage www.nema.org

  12. Reference ArticlesReference UL 1 and NEC • NEMA RV 3 1.4.1 – National Electric Code • NEMA RV 3 1.4.2 – Related NEC Articles • NEMA RV 3 1.4.3 – UL Standards • Guide information page: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/index.htm • White book “Guide Information for Electrical Equipment” www.nema.org

  13. Application Guidelines for LFMC • Construction of LFMC • Grounding and Bonding • Marking • Uses Permitted and Not Permitted www.nema.org

  14. Construction for LFMC • In accordance with NEC • Complies with safety requirements of UL360 • Interlocked zinc-coated corrosion resistant steel • Trades sizes are 3/8” through 4” • Sizes 3/8” – 1 ¼” have bonding strip enclosed by convolution www.nema.org

  15. Construction – cont. for LFMC • Jacket material is liquid-tight, non metallic • Jacket specifications governed by UL 360 • Fittings for LFMC are constructed to UL 514B www.nema.org

  16. Picture example for LFMC Cut-away view of Liquidtight Flexible Metal Conduit to illustrate construction www.nema.org

  17. Diagram Example for LFMC Cross-section view illustrating interlocking construction www.nema.org

  18. Grounding and Bonding for LFMC • LFMC trade sizes 3/8” – 1 ¼” permitted for equipment bonding: • When installed with listed fittings and; • Flexibility is not required after installation and; • When installed according to NEC Articles 350 and 250 and; • Only in 6’ lengths or less • Sizes 3/8” – 4” may be installed in unlimited lengths provided: • A separate grounding conductor is installed • And installed according to NEC Articles 350 and 250 www.nema.org

  19. Surface Print for LFMC • Manufacturer’s name or location • Trade size • Temperature rating • Burial rating (when applicable) • Flame rating (when applicable) • Current rating (for equipment bonding according to NEC article 250) www.nema.org

  20. Uses Permitted for LFMC • Exposed and concealed locations as follows: • When flexibility or protection from liquids, vapors or solids are required • As permitted by 501.10(B), 502.10, 503.1 and 504.20 • Other hazardous classified locations per 553.7(B) • Direct burial where listed & marked for that purpose • If LFMC is marked direct burial it is also suitable for use in concrete or in poured concrete • The following are references throughout the NEC code: www.nema.org

  21. Uses Permitted –cont. for LFMC • Outside branch circuits and feeders • Under raised floors for computer rooms • Lighting whips and motor leads • These uses are not all inclusive, but serve as guidelines • References throughout the NEC Code: www.nema.org

  22. Uses Not Permitted for LFMC • Where subject to physical damage • Where operating conditions cause temperatures to exceed material ratings • See NEC 350.12 for prohibited uses www.nema.org

  23. Reference Articles for LFMC • NEMA RV 3 2.4.1 – National Electric Code • NEMA RV 3 2.4.2 – Related NEC Articles • NEMA RV 3 2.4.3 – UL Standards • Guide information page: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/index.htm • White book “Guide Information for Electrical Equipment” www.nema.org

  24. Installation Guidelines • Installation Considerations • Securing & Supporting FMC & LFMC • Terminating FMC www.nema.org

  25. Installation Considerations for FMC & LFMC • Minimum centerline bend radius • Table 2 chapter 9 NEC • “Other bends” column • Maximum # of bends between pull points • Not to exceed (4) - 90 degree bends • Or a total of 360 degrees (any direction) www.nema.org

  26. Offset Table 2 3/4" Trade Size 0.75 Overall Length of Conduit for Given Offset and Lateral Distance "B" (in.) "R" Offset Distance (in.) Lateral Dist. 1.0 1.5 2 2.5 3.0 4.0 5.0 6.0 8.0 10.0 7 7.6 8 8.3 8.7 9 9.2 9.5 9.8 10 10.2 10.4 10.6 11.0 11 11.1 11.3 11.5 11.8 12 12.1 12.2 12.4 12.7 13.0 13 13.1 13.2 13.4 13.6 13.8 14.4 14 14.1 14.2 14.3 14.5 14.7 15.3 15 15.1 15.2 15.3 15.5 15.6 16.1 16.7 20 20.0 20.1 20.2 20.3 20.4 20.7 21.2 21.7 22.9 24.4 25 25.0 25.1 25.1 25.2 25.3 25.6 25.9 26.2 27.2 28.3 30 30.0 30.1 30.1 30.2 30.2 30.4 30.7 31.0 31.7 32.7 Lateral Offsets • Use tables for length • Lateral offset • Example below www.nema.org

  27. Vertical Loop • Vertical loop w/offset • L=(8xTS)+(1.57xA) +T/2+F • L = Overall length • TS = Trade size • A = Horizontal dist between fittings • T = Travel distance • F = Offset • This accounts for suggested tangent length www.nema.org

  28. Fittings should be tightened properly Section 3.3, tables 1 and 2 of NEMA guidelines for proper torquing values Closely follow manufacturer's instructions Installation Considerations – cont. for FMC & LFMC www.nema.org

  29. Securing & Supporting FMC & LFMC • According to NEC 348.30 & 350.30 • Both must be supported and secured every 4.5’ or less • Must be secured within 12” of each termination • These support requirements are waived if needed for flexibility or for luminaries www.nema.org

  30. Securing & Supporting – cont. for FMC & LFMC • Both may be unsupported when: • Conduit is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical • Flexibility is required • 3’ maximum for LFMC • 3’ maximum for FMC ½” through 1¼” • 4’ maximum for FMC 1½” through 2” • 5’ maximum for FMC 2½” and larger • Used on luminaries; 6’ maximum • Run through non-vertical framing members with distances not exceeding 4½’ www.nema.org

  31. Terminating FMC • Fitting Selection requires knowing: • Trade size or metric designator • Type of FMC, (standard, reduced or extra-reduced wall) • Type of metal (steel or aluminum) www.nema.org

  32. Conduit Preparation for FMC & LFMC • Square the cut end of the metal conduit • Insert conduit flush with fitting end stop • Ensure seating of clamp on conduit before torquing • Be careful torquing the securement screw • Always follow the manufacturer's instructions • Follow recommendations from NEMA FB 2.20, “Selection and Installation guidelines for Fittings for use with Flexible Conduit and Cable” www.nema.org

  33. Cutting Conduit for FMC • Rotary armor cutters • Hacksaw • Cut one convolution at a 60 degree angle • Diagonal wire cutters • Brake the conduit or twist open • Then cut with the cutters www.nema.org

  34. Cutting Conduit for LFMC • Hacksaw • Blade should have 32 teeth per inch • Band saw with ½” X .025 Blade with 24 teeth per inch at 350 ft/min www.nema.org

  35. Fitting Attachment for FMC • Always make sure the conduit is inserted completely to the smooth end stop • When using a clamp type fitting, be sure the fitting seats between the convolutions • Hand tighten the fitting screws and slightly rotate the conduit in the fitting • If there are two screws, tighten alternately to provide even pressure. • Table 1 in NEMA RV 3 shows standard torque values for FMC fittings www.nema.org

  36. Terminating for LFMC • Fitting Selection requires knowing: • Trade size or metric designator • The environment of installation • Conduit preparation • Square the end of the conduit • Fully insert conduit to end stop • Ensure jacketing is not cut or ripped • Always follow the manufacturers instructions • Follow recommendations from NEMA FB 2.20, “Selection and Installation guidelines for Fittings for use with Flexible Conduit and Cable” www.nema.org

  37. Fitting Attachment for LFMC • Squared end must be fully inserted into ferrule • Assembly methods vary for LFMC fittings, follow manufacturer's instructions • Table 2 in NEMA RV 3 show standard torque values for LFMC fittings www.nema.org

  38. Unthreaded Entries • Hand tighten the threaded portion of fitting to secured box using a locknut • Assemble nut, gland and ferrule onto conduit • After securely tightening the gland nut to the threaded body, finish tightening the locknut ¼ turn www.nema.org

  39. Fitting Example www.nema.org

  40. Verification of Installation • Conduit shall be properly terminated at boxes • Conduit shall be properly secured and supported • Conduit shall not show evidence of damage or physical abuse www.nema.org

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