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Helpful Wire Jackets Chart

Below you will find a chart to help you understand what the different kinds of wire jackets are and what they are used for. This is stamped or etched into the outer jacket of the wire so you can tell what kind of wire you are using. We hope this chart will make that easier for you.

O: Oil-resistant, usually synthetic-rubber jacket, more flexible in cold temperatures

OO: Oil-resistant synthetic-rubber jacket and inner-conductor insulation

S: Standard service (synthetic-rubber insulated, rated for 600v)

SE: Extra-hard usage, elastomer

SEOW: Oil-resistant and weather-resistant elastomer jacket, rated for 600v (photo above)

SJ: Service junior (synthetic-rubber insulated, rated for 300v)

SJO: Same as SJ but Neoprene, oil resist compound outer jacket, rated for 300v

SJOW: Oil-resistant and weather-resistant synthetic rubber, rated for 300v

SJOOW: Oil-resistant and weather-resistant synthetic rubber (jacket and conductor insulation), rated for 300v

SJT: Hard service thermoplastic pr rubber insulate conductors with overall plastic jacket, rated for 300v

SJTOW: Oil-resistant and weather-resistant thermoplastic, rated for 300v

SJTW: Thermoplastic-jacketed, weather-resistant, rated for 300v

SO: Extra hard service cord with oil resistant rubber jacket, 600v

SOOW: Same as SOW but with oil resistant rubber conductor insulation and suitable for outdoor use.

SOW: Rubber jacketed portable cord with oil and water resistant outer jacket

SPT-1: All rubber, parallel-jacketed, two-conductor light duty cord for pendant or portable use, rated for 300v

SPT-2: Same as SPT-1, but heavier construction, with or without third conductor for grounding purposes, rated for 300v

SPT-3: Same as SPT-2, but heavier construction for refrigerators or room air conditioners, rated for 300v

ST: Extra-hard usage, thermoplastic (PVC), 600v

STO: Same as ST but with oil resistant and thermoplastic outer jacket, 600v

STOW: Same as STO but with oil and water resistant thermoplastic outer jacket, 600v

SV: Vacuum cleaner cord, two or three conductor, rubber insulated, rubber jacket, 300v

SVO: Same as SV except neoprene jacket, 300v

SVT: Same as SV except all thermoplastic construction, 300v

SVTO: Same as SVT except with oil resistant jacket, 300v

THHN: 600v nylon jacketed building wire

THW: Thermoplastic vinyl insulated building wire, moisture and heat resistant

THWN: Same as THW but with nylon jacket

W: Extra-hard usage, weather-resistant