NEMA RV 3 Application

1
NEMA RV 3Application Installation Guidelines
For Flexible Liquid Tight Flexible Metal
Conduits

2
Application Guidelines for FMC

• Construction of FMC
• Grounding and Bonding
• Uses Permitted and Not Permitted

3
Construction for FMC

• Constructed in accordance with NEC
• Complies with safety requirements of UL1
• Interlocked corrosion resistant steel or Aluminum
  strip

4
Picture Example for FMC

5
Diagram Example for FMC
Cross-section view illustrating interlocking
construction
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

7
Product Marking for FMC

• Manufacturers designation
• UL Logo
• Conduit type
• Reduced wall (RW)
• Extra reduced wall (XRW)
• Material type
• Aluminum (AL)
• Steel (No Mark Required)

8
FMC Marking Example
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

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

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

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

13
Application Guidelines for LFMC

• Construction of LFMC
• Grounding and Bonding
• Marking
• Uses Permitted and Not Permitted

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

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

16
Picture example for LFMC

Cut-away view of Liquidtight Flexible Metal
Conduit to illustrate construction
17
Diagram Example for LFMC

Cross-section view illustrating interlocking
construction
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

19
Surface Print for LFMC

• Manufacturers 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)

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

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

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

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

24
Installation Guidelines

• Installation Considerations
• Securing Supporting FMC LFMC
• Terminating FMC

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)

26
Lateral Offsets

• Use tables for length
• Lateral offset
• Example below

27
Vertical Loop

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

28
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

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

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

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)

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

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

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

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

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

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

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

39
Fitting Example
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