14.1 Flexible Cords, Flexible Cables & Fixture Wires (Articles 400 & 402)

Why cords are tested

Cords are the most abused wiring method on job sites and in buildings. DLI's knowledge areas include flexible cords and cables and fixture wires. Most questions ask whether a cord use is permitted, what type of cord is needed, or how much current it can carry.

Uses permitted (400.10)

Flexible cords and flexible cables are permitted 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 whose fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, where the appliance is intended or identified for cord connection;
9. connection of moving parts;
10. where specifically permitted elsewhere in the Code; and
11. between an existing receptacle outlet and an inlet that supplies an additional single receptacle outlet, under specific conditions.

For items 3, 6, and 8, the cord must have an attachment plug and be energized from a receptacle outlet or cord connector body (400.10(B)).

Uses not permitted (400.12)

Unless specifically permitted elsewhere, flexible cords and cables may not be used:

1. as a substitute for the fixed wiring of a structure;
2. where run through holes in walls, structural ceilings, suspended or dropped ceilings, or floors;
3. where run through doorways, windows, or similar openings;
4. where attached to building surfaces;
5. where concealed by walls, floors, or ceilings, or located above suspended or dropped ceilings;
6. where installed in raceways, except as otherwise permitted; or
7. where subject to physical damage.

A common inspection failure is a cord-connected appliance in a ceiling space, such as a projector or condensate pump plugged into a receptacle above a lay-in ceiling. That cord is located above a suspended ceiling, which 400.12 prohibits, unless another article specifically permits it.

Cord types (Table 400.4)

For example, SJOOW is junior hard service, oil-resistant insulation and jacket, weather resistant. Construction-site cords for temporary power must be listed for hard or extra-hard usage (Article 590). Hard-service cords are marked with their type designation at intervals not exceeding 24 in.

Ampacity (Table 400.5(A)(1))

An equipment grounding conductor does not count as a current-carrying conductor. For more than three current-carrying conductors in a cord, adjustment factors from Table 400.5(A)(3) apply.

Splices, strain relief, and identification

• Splices (400.13): cords must be used only in continuous lengths without splice or tap when initially installed. Hard-service and junior hard-service cords 14 AWG and larger may be repaired by splicing if the completed splice retains the insulation, outer sheath, and usage characteristics of the cord.
• Strain relief (400.14): cords must be connected to devices and fittings so that tension is not transmitted to joints or terminal screws, for example with knots, cord clamps, or fittings designed for the purpose.
• Identification (400.22 and 400.23): the grounded conductor is identified by a white or gray finish, a tracer, ribbing, or similar means; the equipment grounding conductor is green or green with yellow stripes.
• Overcurrent protection (240.5): a flexible cord is considered protected when it is used within the listing of the appliance or portable lamp it supplies. Extension cord sets of 16 AWG and larger are considered protected when used with listed equipment.

Fixture wires (Article 402)

Fixture wires (such as TF, TFF, TFN, SF-2, and PTF) are used in luminaires and similar equipment, and to connect luminaires to branch-circuit conductors. They may not be used as branch-circuit conductors, except where another article permits it, such as for certain power-limited circuits. The minimum size is 18 AWG.

Protection of fixture wire (240.5(B)(2)): on a 20 A circuit, 18 AWG fixture wire may run up to 50 ft and 16 AWG up to 100 ft; 14 AWG and larger is permitted without a length limit. On 30 A circuits, 14 AWG and larger; on 40 A and 50 A circuits, 12 AWG and larger.

Worked example: a cord-connected shop machine

A woodworking machine is cord-and-plug connected so it can be moved for maintenance. Its nameplate is 12 A at 240 V, single phase.

1. The use is permitted for frequent interchange or ready removal, with an attachment plug and a receptacle.
2. The cord has two current-carrying conductors and an EGC, so use Column B: 16 AWG is 13 A, which carries 12 A, but a hard-usage cord of 14 AWG (18 A) is the practical choice for a shop.
3. The cord must have strain relief at both ends and may not be stapled along the wall or run through it.