Short answer: 250.118 is the list of what may serve as an equipment grounding conductor: wire types, and certain raceways, cable armor and sheaths when they meet stated conditions. Flexible raceways qualify only under narrow conditions. For example, listed liquidtight flexible metal conduit (LFMC, Article 350) in trade sizes 3/8 through 1/2 can serve as the equipment grounding conductor only where it ends in listed fittings, the circuit overcurrent devices are rated 20 A or less and the total flexible length in the ground-fault path is not more than 6 feet (NEC 250.118(A)(6)(b)). Miss one condition and a wire-type equipment grounding conductor goes in the run. A run installed for flexibility, such as for vibration or movement, also needs one. Flexible metal conduit (FMC, Article 348) has its own conditions in the same list; check them in your 2026 NEC.
PSI lists raceways in the Wiring Methods and Materials subject area of the Texas Journeyman exam: 10 scored NEC Knowledge questions and 2 scored Calculations questions. PSI does not say how many cover flexible conduit or 250.118. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Why flexible conduit is treated differently
Rigid raceways have solid walls and tight fittings, so they make a low-impedance path back to the source. Flexible metal conduit is a spiral of metal strip, and the path runs through many small contact points and fittings. So the NEC limits when the metal of a flexible raceway can serve as the fault path. The conditions depend on the raceway type and include trade size, overcurrent device rating, total flexible length and listed fittings.
FMC or LFMC: which one goes where
| Raceway | Article | Typical use |
|---|---|---|
| Flexible metal conduit (FMC) | 348 | Dry locations, short connections to equipment that moves or vibrates |
| Liquidtight flexible metal conduit (LFMC) | 350 | Where flexibility is needed or the run needs protection from liquids, vapors or solids (NEC 350.10(1)) |
When a question describes exposure to liquids, vapors or solids, check the uses permitted for LFMC in 350.10. An outdoor location alone does not decide the wiring method; read the actual conditions. AC cable is not permitted in wet locations (NEC 320.12).
The LFMC checklist, one condition at a time
To let listed LFMC serve as the equipment grounding conductor in trade sizes 3/8 through 1/2, all of these must be true (NEC 250.118(A)(6)(b)):
- Trade size 3/8 through 1/2.
- Overcurrent device for the circuit rated 20 A or less.
- Total flexible length in the same ground-fault return path not over 6 feet. Add every flexible piece in that path, of any flexible raceway type, not just one whip.
Also check that the conduit ends in listed fittings. If the run is installed to give flexibility after installation, such as to reduce vibration or allow movement, a wire-type equipment grounding conductor or bonding jumper is required instead; check that condition in 250.118 in your 2026 NEC. Larger LFMC sizes have their own conditions in the same section; check them in your 2026 NEC. If the raceway does not qualify, run a wire-type equipment grounding conductor sized from Table 250.122.
Worked example: three whips
A 1/2-inch listed LFMC whip, 4 feet long, connects fixed equipment. Assume the run is not installed for flexibility after installation, the fittings are listed, and no other flexible sections are in the same ground-fault path.
- Circuit at 20 A. Size 1/2 is in range, 20 A is not over 20 A, and 4 feet is not over 6 feet. Under those assumptions, the LFMC may serve as the equipment grounding conductor.
- Same whip, circuit at 30 A. The overcurrent device is over 20 A. A wire-type equipment grounding conductor is required, sized from Table 250.122.
- Two 4-foot whips in the same ground-fault path, circuit at 20 A. The total flexible length is 8 feet, over 6 feet. A wire-type equipment grounding conductor is required.
Other items in the 250.118 list worth knowing
- Type MC cable. The grounding path can be an internal wire-type equipment grounding conductor, or a sheath construction listed and identified for it. Ordinary interlocked armor alone does not qualify. Interlocked armor needs the combined sheath and bare grounding or bonding conductor to be listed and identified; smooth or corrugated tube sheaths need the sheath itself listed and identified (NEC 250.118(A)(10)(b)). For the cable articles themselves, see NEC 334, 330 and 400 cables and cords.
- A grounding electrode conductor is not an equipment grounding conductor. In 2026 this rule, which used to be 250.121, sits in 250.118(B)(1). The exception lets one wire-type conductor serve as both when it meets the requirements for both (NEC 250.118(B)(1) Exception).
- Building steel is not an equipment grounding conductor. The 2026 NEC lists the structural metal frame of a building as not permitted to serve as one (NEC 250.118(B)(2)).
Check yourself
- A question describes a 3/4-inch flexible metal raceway on a 20 A circuit. What do you identify before deciding whether the raceway can serve as the equipment grounding conductor? Whether it is FMC or LFMC. FMC qualifies only on circuits protected at 20 A or less; the 3/8 through 1/2 rule is for LFMC, so 3/4-inch LFMC needs its separate conditions.
- A 1/2-inch LFMC whip of 5 feet and a second LFMC whip of 2 feet are in the same ground-fault path on a 15 A circuit. Can the LFMC serve as the equipment grounding conductor? No. The total is 7 feet, over 6 feet.
- Can a building’s structural steel frame serve as the equipment grounding conductor? No.
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Find 250.118 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Underline the size, rating and length limits in each flexible conduit item of 250.118 in the same color, so all three conditions show up together when you scan the list. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
Can liquidtight flexible metal conduit be used as a ground?
Listed LFMC in trade sizes 3/8 through 1/2 can serve as the equipment grounding conductor where the circuit overcurrent devices are rated 20 A or less and the total flexible length in the ground-fault path is not over 6 feet. Larger sizes have their own conditions.
What happens if the flexible conduit does not qualify?
A wire-type equipment grounding conductor or a permitted bonding jumper provides the fault path. A wire-type equipment grounding conductor is sized from Table 250.122.
Where is the old 250.121 rule in the 2026 NEC?
In 250.118(B)(1): a grounding electrode conductor is not an equipment grounding conductor, with an exception for one wire that meets the requirements for both.
When is LFMC used instead of FMC?
Where the run needs flexibility or protection from liquids, vapors or solids, as Article 350 permits.
Are raceways on the Texas Journeyman exam?
PSI lists raceways in Wiring Methods and Materials: 10 scored NEC Knowledge questions and 2 scored Calculations questions.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, 250.118, Table 250.122, Articles 320, 348 and 350
