WELDING CABLE AND PORTABLE CORD, #6 TO 4/0 AND LARGER

Welding Cable Is Its Own Article

Welding cable is a single-conductor cable built for the secondary side of an arc welder: fine-stranded copper, a rubber jacket and a 600 volt rating, in sizes from 6 AWG through 4/0 and larger. Article 630 treats it separately, and so do the ampacity tables, because a welder lead is sized by duty cycle rather than by the continuous rating used for building wire.

Stranding is the number that matters. Class K cable is built from 30 AWG strands and Class M from 34 AWG, which is why a 2/0 welding lead feels like rope and a 2/0 building conductor feels like pipe. The finer the strand, the more the cable costs to make, and the more it is worth as surplus if the jacket has survived.

• Sizes 6, 4, 2, 1, 1/0, 2/0, 3/0 and 4/0, with 250 to 500 MCM in heavier leads.
• 600 volts, with a jacket temperature rating printed by the manufacturer.
• Neoprene or EPDM jacket, oil resistant, flame retardant and sunlight resistant.
• Class K stranding at 30 AWG and Class M at 34 AWG; both flex, M more so.
• Black, red, blue, green and orange jackets, with red and black the common pair.

Reading a Portable Cord Letter Code

Portable cord is named letter by letter, and each letter answers a question. S is a 600 volt hard-service cord; SJ is the 300 volt junior version with smaller conductors. The first O is an oil-resistant jacket, the second O is oil-resistant insulation, and W means the cord is rated for wet locations and outdoor use.

A T replaces the rubber with thermoplastic, which is cheaper and stiffer. A P means the conductors are parallel rather than twisted. That is why SOOW, SJOOW, STW and SJTW are not interchangeable: two letters change the voltage, the temperature and whether the cord may be used outdoors at all.

Cord Sets, Festoon and Stage Cable

Cord sets are the finished articles: molded generator cords, range and dryer cords, RV cords, L5-30 and L14-30 assemblies, CS6364 and CS6365 stage connectors, and the 12/3 and 10/4 extension cords that get left on site. They are bought as cord and connector together, and the connector type is worth a photograph.

Festoon cable hangs in a loop from a crane or hoist trolley and flexes thousands of times a shift, so it is built flat or round with a high strand count and an abrasion-resistant jacket. Stage cable is the entertainment version of the same problem: 12/3 and 14/3 SOOW, six-circuit multicable and 19-pin assemblies, usually black and always coiled hard.

• Molded cord sets with plug and receptacle still attached.
• Generator and transfer-switch cords in 10/4 and 6/4.
• Stage multicable and 19-pin fan-out assemblies.
• Flat and round festoon cable with the support core intact.
• Bulk SOOW and SJOOW on 250 and 500 foot coils.

Jackets, Flexibility and What Wears Out

Jacket condition decides most of the value. Rubber jackets fail by ozone cracking, abrasion, cuts and heat, and a cable dragged across a shop floor for three years shows all four. A deep cut that reaches copper retires that section, and a lead with several such cuts is priced as shorter usable pieces.

Flexibility is the second test. Bend the cable: a lead that has stiffened has usually been overheated or has absorbed oil, and it will not lie flat in a feeder. Water wicked down the strands from an open end is the third problem, and it is the one a photograph cannot show.

Photograph and Note

Uncoil three feet and photograph the print, then photograph the jacket damage honestly. The print gives the type and the voltage, and on better cable it gives the stranding class. The jacket gives the condition, which is most of the price.

The offer stops at wire and cable. Transformers, switchgear, breakers, motor control centers, generators, chillers and machinery are outside it, and a welder itself counts as machinery. Tray-rated portable power cable belongs with MC and tray cable, plant maintenance stock is described under manufacturing and industrial, and the quote form starts either conversation.

• The print on the jacket, unrolled flat and legible.
• The cut end, showing strand fineness and whether the copper is bright or dark.
• Any cuts, cracks or flat spots, photographed close.
• The full coil, so length and coiling are visible.
• Cord sets with the connectors in frame, so the configuration can be identified.