SOOW cord: portable power from 18/3 to 2/4

Reading the letters before the number

In SOOW, the S means flexible stranded cord, the O means oil resistant jacket, the second O means oil resistant insulation, and the W means moisture and weather resistant. Add a J and the cord becomes junior, a lighter construction rated 300 volts rather than 600. Add a T in place of the W and the jacket is thermoplastic rather than thermoset rubber.

So SOOW and SJOOW are the rubber cords, rated 600 and 300 volts respectively, and STOW is the thermoplastic version of the same idea. All three are outdoor-capable because of the W. A cord marked SO or SJT without the W is an indoor cord, and putting it on a jobsite in February is how jackets crack at the coil. A cord printed W is the only kind that belongs on an Ohio site in January.

Temporary power and cord reels

The big consumer of portable cord is temporary power: stringing circuits across a site before the permanent wiring exists, feeding spider boxes, task lighting and small tools. It is installed in a hurry, run over, coiled wet, and pulled out again at the end of the job. A two-inch cord with a moulded cap on one end is the unit of the trade.

Cord reels are the other source. A retractable reel with fifty feet of 12/3 SOOW that has failed its annual inspection is replaced as a unit, and the cord on it may be perfectly good apart from a worn section where it left the reel. That worn section is at a predictable spot, which is why a reel cord is often cut into shorter usable lengths rather than condemned.

Contractor yards and mixed pallets

Portable cord accumulates in the yards that serve the trades rather than at the plants. A Strongsville yard with I-71 and turnpike access takes in cord from jobs all over the northeast, and it arrives as a mixed pallet: ten-foot 12/3 pieces with moulded ends, twenty-five-foot 10/4 for a distribution box, a coil of 18/3 for control, and a tangle that nobody wants to identify.

The mixed pallet is where lots are lost. Cord is easy to identify by print and easy to measure, but only if someone separates it first. A single photograph of a heap tells a buyer nothing except that the seller has not looked at it either.

Sorting a cord lot

Separate by gauge and conductor count, then by length, then by whether ends are moulded or field-wired. Field-wired ends are usually cut off before resale, so a cord's usable length is measured from behind the cap.

• Gauge and conductor count, for example 12/3 or 10/4
• Type letters, SOOW, SJOOW or STOW
• Length of each piece, measured with the ends in place
• Whether ends are moulded, field-wired or cut off
• Jacket damage: flat spots, cuts, cracks at the coil