10.1 Flexible Cords, Cables and Fixture Wires

Permitted Uses — 400.7

Flexible cords and flexible cables shall be used only for:

1. Pendants;
2. Wiring of luminaires;
3. Connection of portable luminaires, portable and mobile signs, or appliances;
4. Elevator cables;
5. Wiring of cranes and hoists;
6. Connection of utilization equipment to facilitate frequent interchange;
7. Prevention of the transmission of noise or vibration;
8. Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection;
9. Connection of moving parts;
10. Where specifically permitted elsewhere in the Code.

400.7(B) requires that where used as permitted in (3), (6), and (8), each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet or cord connector body.

Uses Not Permitted — 400.12

Unless specifically permitted in 400.10, flexible cords and cables shall not be used for the following:

1. As a substitute for the fixed wiring of a structure;
2. Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors;
3. Where run through doorways, windows, or similar openings;
4. Where attached to building surfaces, with an exception permitting cords to be attached to building surfaces in accordance with 368.56(B) for busway plug-in connections;
5. Where concealed by walls, floors, or ceilings, or located above suspended or dropped ceilings, with exceptions for specified listed assemblies;
6. Where installed in raceways, except as otherwise permitted in the Code;
7. Where subject to physical damage.

Item 2 is the one that catches the most installations. A cord run through a hole in a wall to power a shop tool in the next room is a violation regardless of how neatly it is done.

Decoding Cord Type Letters

So SOOW is extra-hard usage, oil-resistant insulation and jacket, and outdoor rated. SJTW is junior hard service, thermoplastic, outdoor rated at 300 volts. SEOOW is extra-hard usage, thermoplastic elastomer, doubly oil resistant, outdoor rated.

Read the letters in order and the cord tells you what it is. Table 400.4 is the master table of trade names, type letters, size, number of conductors, insulation, braid, and use.

Ampacity — Table 400.5(A)(1)

Flexible cords have their own ampacity table, distinct from Table 310.16 for building wire. Values depend on the number of current-carrying conductors in the cord:

Table 400.5(A)(3) provides adjustment factors where more than three current-carrying conductors are present: 4 through 6 conductors at 80 percent, 7 through 9 at 70 percent, and so on, paralleling the raceway adjustment table.

400.5(B) notes that a grounded conductor carrying only unbalanced current from other conductors, as in a three-wire circuit, need not be counted, and an equipment grounding conductor is never counted.

240.5 Protection of Flexible Cords, Flexible Cables, and Fixture Wires. Flexible cord and cable shall be protected against overcurrent by either the branch-circuit overcurrent device or by supplementary overcurrent protection. 240.5(B)(1) permits specific cord sizes on branch circuits: 18 AWG cord and larger on a 20-ampere circuit, and 16 AWG and larger on a 20-ampere circuit, under stated conditions for listed appliances and luminaires.

Strain Relief and Terminations

400.10 Pull at Joints and Terminals. Flexible cords and flexible cables shall be connected to devices and to fittings so that tension is not transmitted to joints or terminals. Suitable means include: knotting the cord; winding with tape; using a fitting designed for that purpose; or other approved means.

400.14 Protection from Damage. Flexible cords and cables shall be protected by bushings or fittings where passing through holes in covers, outlet boxes, or similar enclosures.

400.17 Fixture Wires and Flexible Cords in Show Windows and Show Cases and 400.16 Overcurrent Protection complete the general requirements.

400.36 Uses Not Permitted (Portable Cables Over 600 Volts) and Part III of Article 400 cover portable cables above 600 volts.

Fixture Wires — Article 402

402.3 and Table 402.3 list the types of fixture wire — TFN, TFFN, THHN as fixture wire, SF-2, PF, PAF, and others — with their maximum operating temperature, application, insulation, and outer covering.

402.5 and Table 402.5 give allowable ampacities: 18 AWG at 6 amperes, 16 AWG at 8 amperes, 14 AWG at 17 amperes, 12 AWG at 23 amperes, and 10 AWG at 28 amperes.

402.6 Minimum Size. Fixture wires shall not be smaller than 18 AWG.

402.7 Number of Conductors in Conduit or Tubing. The number of fixture wires permitted in a single conduit or tubing shall not exceed the percentage fill specified in Table 1, Chapter 9.

402.10 Uses Permitted. Fixture wires shall be permitted for installation in luminaires and in similar equipment where enclosed or protected and not subject to bending or twisting in use, or for connecting luminaires to the branch-circuit conductors supplying the luminaires.

402.11 Uses Not Permitted. Fixture wires shall not be used as branch-circuit conductors except as permitted elsewhere in the Code.

402.12 Overcurrent Protection. Overcurrent protection for fixture wires shall be as specified in 240.5.

Cold-Weather Cord Selection in Alaska

The Code does not set a minimum ambient temperature for cord use; it delegates that to the product listing through 110.3(B). What matters in practice is that thermoplastic jackets stiffen and crack at low temperature, while thermoset and thermoplastic elastomer jackets stay flexible far colder.

Manufacturers publish minimum installation and flexing temperatures for specific cords, and those published limits are enforceable through 110.3(B) when they are part of the listing or labeling. That is the correct Code basis for a cold-weather cord requirement — Alaska adopts the NEC without technical amendments, so there is no state rule mandating a particular cord type.

Two related Alaska realities worth naming:

• Engine block heater cords. Ubiquitous in Interior Alaska. These are cord-and-plug connections to portable equipment, permitted under 400.7(A)(3), and the receptacle they plug into outdoors requires GFCI protection under 210.8(A)(3) for dwellings or 210.8(B)(4) for other occupancies. The dedicated-circuit exception in 210.8(A)(3) applies to snow-melting and deicing equipment under 426.28, not to block heaters.
• Temporary construction power. Article 590 governs, and 590.6(A) requires GFCI protection for all 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets used by personnel during construction. Cords on a winter job site take a beating; 400.12(7) prohibits use where subject to physical damage, and a cord frozen into ice and driven over is exactly that condition.