Liquid Tight Flexible Conduit generator span

conduitelectrical

I can't find a specific answer for this situation. I know that flexible conduit can be used as a 6 foot whip for luminary and "other equipment". It can be used over 6 feet. The question that I can't seem to answer is if a whip exceeds 6 feet and needs supported every 4.5 foot span, does that include the support of the 6 foot whip.

Ie does a 6 foot whip become 4.5 feet between supports. If a 10 foot section of flexible conduit 5 feet from a building has to be supported ever 4.5 feet?

So ultimately, I am asking if a 10 foot section of flexible conduit, can span 6 feet between a building and a generator without additional support between the two?

Best Answer

The NEC doesn't define a "whip" or uses of a whip. For each raceway type the code gives support requirements and exceptions. Since you are referencing 4.5' you must be referencing Liquidtight Flexible Metalic Conduit LFMC, since Non-metallic LFNC requires 3 ft support. LFMC Section 350.30 says:

350.30 Securing and Supporting. LFMC shall be securely fastened in place and supported in accordance with 350.30(A) and (B).

(A) Securely Fastened. LFMC shall be securely fastened in place by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other conduit termination and shall be supported and secured at intervals not to exceed 1.4 m (4'/2 ft).

Exception No. 1: Where LFMC is fished between access points through concealed spaces in finished buildings or structures and supporting is impractical.

Exception No. 2: Where flexibility is necessary after installation, lengths shall not exceed the following:

(1) 900 mm (3 ft) for metric designators 16 through 35 (trade sizes 1/2 through l 1/4)

(2) 1200 mm (4 ft) for metric designators 41 through 53 (trade sizes 1 1/2 through 2)

(3) 1500 mm (5 ft) for metric designators 63 (trade size 2.5) and larger

Exception No. 3: Lengths not exceeding 1.8 m (6 ft) from a luminaire terminal connection for tap conductors to lumi-naires, as permitted in 410.117(C).

Exception No. 4: Lengths not exceeding 1.8 m (6 ft) from the last point where the raceway is securely fastened for connections within an accessible ceiling to luminaire(s) or other equipment.

(B) Supports. Horizontal runs of LFMC supported by openings through framing members at intervals not greater than 1.4 m (4'/2 ft) and securely fastened within 300 mm (12 in.) of termination points shall be permitted.

None of the exceptions allow the last 6' of LFMC as you described to not be supported. You could argue that generator vibration would require flexibility as described in Exception 2, but you may not win that argument because you may need to justify how a support would limit flexibility.

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