SOOW and SJOOW are flexible portable cords covered by NEC Article 400. The letters are a specification, not a brand: S for 600 V service cord, J for the 300 V junior version, OO for oil-resistant jacket and oil-resistant insulation, and W for weather and water resistance including sunlight. Ampacity comes from NEC Table 400.5(A)(1), not from Table 310.16.
| Property | Value |
|---|---|
| SOOW voltage rating | 600 V |
| SJOOW voltage rating | 300 V |
| Temperature rating | Typically −40°C to 90°C; 105°C versions exist |
| Jacket | Thermoset CPE or neoprene, oil and weather resistant |
| Conductor | Fine-stranded annealed copper for flexibility |
| Sizes | 18 AWG through 2 AWG |
| NEC article | Article 400, ampacity from Table 400.5(A)(1) |
| Sunlight resistance | Yes — that is what the W denotes |
| Fixed wiring | Not permitted as a substitute (NEC 400.12) |
| Typical use | Portable tools, temporary power, stage and event, machine drops |
| Size | Column A — 2 current-carrying conductors | Column B — 3 current-carrying conductors |
|---|---|---|
| 18 AWG | 10 A | 7 A |
| 16 AWG | 13 A | 10 A |
| 14 AWG | 18 A | 15 A |
| 12 AWG | 25 A | 20 A |
| 10 AWG | 30 A | 25 A |
| 8 AWG | 40 A | 35 A |
| 6 AWG | 55 A | 45 A |
| 4 AWG | 70 A | 60 A |
| 2 AWG | 95 A | 80 A |
S — hard service cord, 600 V. SJ — junior hard service, 300 V, thinner jacket, lighter duty. E — thermoplastic elastomer insulation. O — oil-resistant jacket. OO — oil-resistant jacket and oil-resistant conductor insulation. W — weather and water resistant, and suitable for outdoor use including sunlight exposure.
So SOOW is 600 V, oil resistant inside and out, weather rated. SJOOW is the same construction at 300 V. SOW would be oil-resistant jacket only. The order of the letters is fixed by the standard, which is why the codes look cryptic but parse cleanly once you know the key.
NEC 400.12 is explicit about what flexible cord may not do, and it is the most violated rule in Article 400. Cord may not be used as a substitute for the fixed wiring of a structure. It may not be run through holes in walls, ceilings or floors, or through doorways and windows. It may not be concealed behind walls or above suspended ceilings, or attached to building surfaces except where specifically permitted.
The permitted uses in NEC 400.10 are the mirror image: pendants, wiring of luminaires, connection of portable equipment, elevator cables, connection of appliances designed for ready removal, and equipment that must be moved for maintenance. If the load is not intended to move or be removed, it needs building wire in a raceway or a cable assembly, not cord.
Because cord conductors are fine-stranded and bundled in a flexible jacket with no air gap, they use NEC Table 400.5(A)(1) rather than Table 310.16. Column A applies to cords with two current-carrying conductors, Column B to cords with three. Cords with four to six current-carrying conductors derate to 80%, and seven to nine to 70%.
The values are meaningfully lower than building wire. 12 AWG SOOW with three conductors is 20 A, matching 12 AWG THHN by coincidence — but 6 AWG SOOW is 45 A where 6 AWG THHN in conduit is 65 A. Size portable cord from Table 400.5, never from the building wire tables.