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portable cord letters

Portable Cord Letters Explained

From contractors with power tools to families powering their holiday lights, everyone uses extension cords. We thought it would be helpful to define those pesky letters found on portable cord packaging and cable manufacturer websites. On the packaging of some portable cords (and on all of the service cords on our website), you'll see a set of letters. These letters indicate the set of ratings applicable to the cord.

Portable Cord Letter Meanings

Letter Meaning Explanation
S Service Severe heavy duty Service. These cords are portable cords that have a voltage rating of 600V (also 277/480 or 480) and can be used in place of SJ or SV in extra-severe service where abrasion resistance is needed.
J Junior Service These service cords have a rating of 300V (also 120 or 120/208 or 120/240 or 240 or 277, but not 277/480). Examples include SJ, SJO, SJOW, and SJT.
T Tinsel Cord Only applicable if it is the first letter of the code for a portable cord. Example: TTXOW.
T Thermoplastic (if not the first letter of code) This refers to the material the cord jacket is made out of. Thermoplastic material is light-duty and can be used as a consumer-grade portable cord. Examples include SJT, SPT, and SVT.
E Elastomer Short for Thermoplastic Elastomer, a flexible thermoplastic that looks and feels like rubber. This refers to the material the cord jacket is made out of. Thermoplastic elastomer material is medium-duty and performs better in colder temperatures than thermoplastic. (If a portable cord does not have a ‘T’ or an ‘E’, it is made of thermoset material, which makes it heavy-duty.) Examples include SEO/SEOW and SJEOOW.
N Nylon Outer jacket material.
O Oil-Resistant Outer Jacket Examples include SEO, SO, STO, and SVO.
OO Both the outer jacket and the insulation are oil resistant Examples include SJOOW and SOOW.
F Fixture Wire These cables are rated to 90°C. Examples include H07RN-F.
P Parallel This cable is parallel-jacketed, meaning the conductors are not twisted around each other. Sometimes called "zip cord." Examples include SPT.
H Heat Resistant Referred to as heater cord. This is used in UL cord types like HSJ, HS, HSO, and HSJO.
HH High Heat Resistant.
V Vacuum Cord This is a light-duty portable cord, rated at 300 volts. Typically used with vacuum cleaners and other portable cleaning equipment. "V" is the UL marking in parts like SVT and SVO.
RD Range or Dryer cord Product examples include SRD, SRDE, and SRDT cord.
W-A Weather Resistant UL approved for indoor and outdoor use. Examples include SEOO-WA and SJTO-WA.
W Weather and Water Resistant A portable cord with a W means it’s approved as weather (sunlight, moisture, etc.) and water-resistant and can be used indoors or outdoors. Examples include SEOW and SJOOW.

For a more visual approach check out our Power Cord Basics video below. The next time you’re in the market for some portable cordage, either from a manufacturer/distributor or from your local hardware store, you’ll be armed with the right information to make the correct choice for your needs!