NEC 342 IMC and 360 Flexible Metallic Tubing for the Journeyman Exam: Where Each Is Allowed, Sizes, Bends and the 6-Foot Limit

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 these two show up on the exam

Most raceway questions are about EMT, PVC and rigid metal conduit, covered on NEC 344, 352 and 358 raceway installation rules. IMC and FMT are tested because they look like their better-known cousins but have their own article and their own limits. The usual traps: thinking IMC cannot go where rigid conduit goes, and thinking FMT is the same as flexible metal conduit.

Item	IMC (Article 342)	FMT (Article 360)
What it is	Rigid steel conduit, threadable, thinner wall than RMC	Flexible, liquidtight metal tubing, no jacket
Where it can go	All atmospheric conditions and occupancies, concrete, wet locations, severe physical damage	Dry, accessible locations, branch circuits, 1000 volts or less
Trade sizes	1/2 through 6	1/2 and 3/4; 3/8 in limited uses
Length limit	None in the article	Not over 6 feet
Bends	360 degrees total between pull points	Bend radius from the tables in the article

IMC: the rules that get tested

• Uses permitted. All atmospheric conditions and occupancies, in concrete and in direct contact with the earth with corrosion protection where needed, in wet locations, and where subject to severe physical damage (NEC 342.10).
• Dissimilar metals. Where practicable, avoid contact between dissimilar metals in the run so galvanic action does not eat the conduit (NEC 342.14).
• Size. Trade size 1/2 is the smallest and trade size 6 is the largest (NEC 342.20). Whether a large size is easy to buy is a separate question from what the code allows.
• Fill. The number of conductors follows the conduit fill tables in Chapter 9 (NEC 342.22).
• Bends. Made without damage and without reducing the inside diameter (NEC 342.24), and no more than the equivalent of four quarter bends, 360 degrees total, between pull points (NEC 342.26).
• Reaming. Cut ends are reamed to remove rough edges (NEC 342.28).
• Securing and supporting. Generally fastened within 3 feet of each outlet box, junction box, device box, cabinet, conduit body or other termination, and supported at intervals of not more than 10 feet (NEC 342.30). The section has exceptions, including longer securing distances where structural members do not allow 3 feet and longer support spacing for straight runs with threaded couplings under the rigid metal conduit support table. Read the exception that fits the question instead of applying 3 and 10 feet everywhere.
• Couplings and connectors. Couplings and connectors are made up tight. Fittings used in concrete or masonry are listed for concrete-tight use, and fittings used in wet locations are listed for wet locations (NEC 342.42). Check the 2026 wording of this section in your own code book, because it was revised.

FMT: the rules that get tested

• Uses permitted. Branch circuits, in dry locations, where concealed, in accessible locations, at 1000 volts or less (NEC 360.10).
• Uses not permitted. Not in hoistways, storage battery rooms, hazardous locations unless another article allows it, underground or embedded in concrete, where subject to physical damage, and not in lengths over 6 feet (NEC 360.12).
• Size. Trade sizes 1/2 and 3/4. Trade size 3/8 is allowed in the same limited uses where 3/8 flexible metal conduit is allowed (NEC 360.20).
• Fill. Trade sizes 1/2 and 3/4 follow the Chapter 9 fill tables; trade size 3/8 follows the small-conduit table used for flexible metal conduit (NEC 360.22).
• Bends. Where the tubing will flex during use, the bend radius follows one table; where bends are fixed during installation, it follows another (NEC 360.24(A)).

Whether FMT can serve as the equipment grounding conductor depends on its length, its fittings and the circuit rating. That rule lives in Article 250 with the other flexible raceways.

Worked example: bends in an IMC run

An IMC run leaves a panel with a 90-degree bend, has two 45-degree offsets made of two 45-degree bends each, and enters a pull box with another 90-degree bend.

1. Add the bends. 90 + (45 + 45) + (45 + 45) + 90 = 360 degrees.
2. Check the limit. 360 degrees is the maximum between pull points, so the run is at the limit.
3. Add one more bend? A third offset would add 90 degrees and bring the total to 450 degrees. You would need a pull point, such as a conduit body or pull box, to split the run.

Worked example: FMT length

A luminaire whip in a dry, accessible ceiling space needs 7 feet of flexible metallic tubing.

1. Check the length limit. FMT cannot be used in lengths over 6 feet.
2. Result. 7 feet is not allowed. Shorten the run to 6 feet or less, or use a different wiring method that the job and the other articles allow.

Check yourself

1. Can IMC be installed where it is exposed to severe physical damage? Yes.
2. What is the largest trade size of IMC? Trade size 6.
3. Can FMT be installed underground? No.
4. A run has three 90-degree bends and one 45-degree bend. How many degrees remain before the limit? 360 − 315 = 45 degrees.

FAQ

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, Articles 342 and 360