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

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

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

Picture Example for FMC www.nema.org

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

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

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

FMC Marking Example www.nema.org

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

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

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

Reference Articles Reference 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

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

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

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

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

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

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

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

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

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

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

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

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

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

Lateral Offsets Use tables for length Lateral offset Example below Offset Table 2 3/4" Trade Size 0.75 "B" (in.) "R" Offset Distance (in.) 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 15.5 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 25.2 25.3 25.6 25.9 26.2 27.2 28.3 30 30.0 30.1 30.2 30.4 30.7 31.0 31.7 32.7 Overall Length of Conduit for Given Offset and Lateral Distance Lateral Dist. 1.0 1.5 2 2.5 3.0 4.0 5.0 6.0 8.0 10.0 www.nema.org

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

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

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

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

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

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

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

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

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

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

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

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

Fitting Example www.nema.org

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