LFNC Conduit Fill Chart
Liquidtight flexible nonmetallic (LFNC-B) wire capacity, computed from NEC 2023 Chapter 9 Tables 1, 4 and 5.
This is the complete LFNC-B wire fill chart, computed live from NEC 2023 Chapter 9 Tables 4 and 5. Pick an insulation, filter by wire size, then export as CSV or print. For a mixed-conductor whip, use the interactive conduit fill calculator.
- 1/2" LFNC9 wires
- 3/4" LFNC16 wires
- 1" LFNC26 wires
- 1-1/4" LFNC46 wires
- 1-1/2" LFNC59 wires
- 2" LFNC97 wires
| TRADE → WIRE ↓ | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" |
|---|---|---|---|---|---|---|
| 14 AWG | 13 | 22 | 36 | 63 | 81 | 134 |
| 12 AWG | 9 | 16 | 26 | 46 | 59 | 97 |
| 10 AWG | 6 | 10 | 16 | 29 | 37 | 61 |
| 8 AWG | 3 | 6 | 9 | 16 | 21 | 35 |
| 6 AWG | 2 | 4 | 7 | 12 | 15 | 25 |
| 4 AWG | — | 2 | 4 | 7 | 9 | 15 |
| 3 AWG | 1 | — | 3 | 6 | 8 | 13 |
| 2 AWG | 1 | — | 3 | 5 | 7 | 11 |
| 1 AWG | 1 | — | — | 4 | 5 | 8 |
| 1/0 | 1 | 1 | — | 3 | 4 | 7 |
| 2/0 | — | 1 | — | 2 | 3 | 6 |
| 3/0 | — | 1 | 1 | — | 3 | 5 |
| 4/0 | — | 1 | 1 | — | 2 | 4 |
| 250 | — | — | 1 | — | — | 3 |
| 300 | — | — | 1 | 1 | — | 3 |
| 350 | — | — | 1 | 1 | — | 2 |
| 400 | — | — | — | 1 | 1 | — |
| 500 | — | — | — | 1 | 1 | — |
| 600 | — | — | — | 1 | 1 | — |
| 700 | — | — | — | 1 | 1 | 1 |
| 750 | — | — | — | — | 1 | 1 |
| 800 | — | — | — | — | 1 | 1 |
| 900 | — | — | — | — | 1 | 1 |
| 1000 | — | — | — | — | — | 1 |
LFNC-B — Liquidtight Flexible × THHN (90°C dry) · NEC 2023 Ch.9 Tables 4 & 5 · 40% (3+), 31% (2), 53% (1)
NOTES & CONTEXT
How to use the LFNC fill chart
Each row is a trade size of liquidtight flexible nonmetallic conduit. The chart uses the LFNC-B interior areas from NEC 2023 Chapter 9 Table 4, because Type B is the variant tabulated there, and conductor areas from Table 5. NEC Chapter 9 Table 1 governs the fill: 53 % for one conductor, 31 % for two, and 40 % for three or more. LFNC is tabulated only through 2 in, so the chart ends there.
What is LFNC?
LFNC is liquidtight flexible nonmetallic conduit under NEC Article 356. It has a smooth or corrugated nonmetallic core with an outer jacket that keeps liquids out, and it flexes by hand. The tabulated form is Type B (LFNC-B), which has the nonmetallic reinforcement between two layers of plastic. Because it is flexible and liquidtight, it is the go-to for the final connection to equipment that moves, vibrates, or sits in a damp spot.
Where LFNC is used and its length limits
The most common LFNC application is a short whip from a rigid raceway or junction box to a piece of equipment: motors, rooftop HVAC units, pool and irrigation pumps, and machinery that vibrates in service. NEC Article 356 limits LFNC to trade sizes 1/2 in through 2 in and restricts its use as a fixed raceway in certain conditions, including length limits where it is used without being secured. Keep whips short and support them per 356.30. For the equivalent metal whip, see the flexible conduit fill chart.
Common LFNC scenarios
- The last 18 to 36 in to a motor terminal box, where vibration would fatigue a rigid connection.
- Final connection to a rooftop air handler or condensing unit exposed to weather.
- Feed to a submersible or jet pump in a wet pit or pump house.
- Connection to machine tools on a shop floor where the equipment shifts or is periodically moved.
Reading the fill limits
The same NEC Chapter 9 Table 1 percentages apply: 53 % for one conductor, 31 % for two, and 40 % for three or more. Whips are short, so it is tempting to cram them, but the fill rule does not relax for length except for the 60 % nipple allowance on runs 24 in or shorter, and even that is measured box-to-box. Flexible raceways also bend, and a tight bend effectively reduces usable area, so leaving margin below 40 % keeps the conductors from binding at the elbow of the whip.
Grounding in LFNC
LFNC is nonmetallic, so it cannot act as the equipment grounding conductor. NEC 356 and 250.118 require a separate grounding conductor pulled inside the whip, and that conductor counts toward the fill total in the chart. On a two-wire-plus-ground motor whip that means you are really filling for three conductors and must use the 40 % column, not the 31 % two-conductor column. Count the ground before comparing to the chart.
Heat de-rating note
This chart is a fill calculation, not an ampacity rating. It only says how many conductors fit under NEC Chapter 9. Whips often bundle several current-carrying conductors, so remember NEC 310.15(C)(1): adjust ampacity to 80 % for 4 to 6 current-carrying conductors, 70 % for 7 to 9, and 50 % for 10 to 20. Short LFNC whips still count toward conduit fill even though they are only a few feet long, and the flexing service they see makes generous margin worthwhile. The chart also assumes uniform 12 AWG THHN; a whip that carries larger phase conductors plus a smaller ground uses different Table 5 areas and a different count. Confirm the exact conductor set in the conduit fill calculator before you cut.