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Cord Designations --
Listed below are designations for cord characteristics based on Underwriters Laboratories (UL) and National Electrical Code (NEC) Article 400.
S = Standard; rated at 600 VAC
SJ = Junior; rated at 300 VAC
E Elastomer; (thermoplastic rubber)
T = Thermoplastic
O = Oil-resistant outer jacket
OO = Oil-resistant insulation and outer jacket
P = Parallel construction (flat)
W = Approved for outdoor use
V = Lightweight, round vacuum cleaner cord
Cord Type Jacket Voltage Rating Duty
SO Thermoset Rubber 600 Heavy
SOW Thermoset Rubber 600 Heavy
SOOW Thermoset Rubber 600 Heavy
SEOW Elastomer 600 Heavy
SEOOW Elastomer 600 Heavy
ST Thermoplastic 600 Heavy
STO Thermoplastic 600 Heavy
STOOW Thermoplastic 600 Heavy
STW Thermoplastic 600 Heavy
SJEW Elastomer 300 Medium
SJO Thermoset Rubber 300 Medium
SJOW Thermoset Rubber 300 Medium
SJOOW Thermoset Rubber 300 Medium
SJEO Elastomer 300 Medium
SJEOW Elastomer 300 Medium
SJEOOW Elastomer 300 Medium
SJT Thermoplastic 300 Medium
SJTO Thermoplastic 300 Medium
SJTW Thermoplastic 300 Medium
SVO Thermoset Rubber 300 Light
SVT Thermoplastic 300 Light
SPT Thermoplastic 300 Light
source : https://www.multicable.com/resources/reference-data/cord-designations/
Letter Designations
SOOW Letter Designations
The letter designations of SO cable come from the National Electric Code. A new edition is published every 3 years by the National Fire Protection Agency (e.g. 2008 and 2011 NEC Handbooks). SOOW cable specifically refers to cable that is rated for up to 600 volt applications, has an oil resistant jacket and insulation, and is weather and water resistant (meaning it can be used outdoors).
Since SOOW cable (now largely sold in place of SO cord) is the most common type of portable control cable people use, you may see the term being used to refer to flexible cable in general. However, keep in mind that SOOW is only a specific type of flexible cable, so be aware of the context in which the term is being used.
Examples
SOOW - Extra hard usage, oil resistant jacket and insulation, for outdoor use.
SJTO - Hard usage, thermoplastic, oil resistant jacket.
SPT-2 - Parallel cord, thermoplastic.
See the table below for a simple breakdown the UL gives of common NEC flexible cable letter designations based on NEC table 400.4.
Flexible Cable Letter Designations
Designation What this means
S Service grade. Extra hard service when not followed by J, P, or V.
SJ Junior hard service. 300 volts
SV Vacuum Service and light duty cable. Originally designed for use with vacuum cleaners but now used for a variety of light duty applications.
P Parallel cord (also known as zip cord). Light duty only.
Parallel cord types SP-1, SP-2, SP-3, SPE-1, SPE-2, SPE-3, SPT-1, SPT-1W, SPT-2, SPT-2W, SPT-3 have only one layer of insulation (see "NI")
E As first letter: Elevator cable
After first letter: Thermoplastic elastomer insulation & jacket (UL/NEC designation only)
EV Electric vehicle cable (such as for use in electric cars)
H Heater cords (cords for heating applications)
NI "Non-Integral." This designation only applies to parallel cords and means the parallel cord has two layers of insulation.
Parallel cords without an "NI" have only one layer of insulation, with no outer jacket.
Add "NI" (e.g. NISPT-2) to indicate a parallel cord with conductor insulation and a jacket covering.
O Oil resistant*
T As first letter: Tinsel cord. Single flattened 27 AWG conductor wound around insulating core, for very low current, highly flexible application.
After first letter: Thermoplastic insulation & jacket
XTW Parallel cord for decorative lighting strings.
CXTW Twisted pair cord or single conductor for decorative lighting strings.
W As last letter: Suitable for use in wet locations and sunlight resistant.
As the only letter: Portable power cable
VW-1 Flame retardant. Passes UL Vertical Wire flame test.
Flame retardant means the cable stops burning once the heat source is gone (not the same as flame proof).
-1, -2, -3 Insulation thickness for parallel cords, thinnest to thickest. Actual insulation thickness varies with cord type and AWG size.
source : https://temcoindustrial.com/product-guides/wire-cable-and-accessories/so-cable/soow-letter-designations
Letter codes
In the United States, letter codes have been defined by Underwriters Labs (UL) to describe various attributes and ratings of portable cords. The Canadian Standards Association (CSA) also has defined similar letter codes, and ongoing standards harmonization should eventually resolve minor differences.[1][2][4][5]
SPT-1 = Service Parallel Thermoplastic, 0.030" Insulation | 18 AWG | 2 or 3 conductors | PVC Insulation | No Jacket | 300 V AC | Indoor Use Only
SPT-2 = Service Parallel Thermoplastic, 0.045" Insulation | 18-16 AWG | 2 or 3 conductors | PVC Insulation | No Jacket | 300 V AC | Indoor Use Only
SPT-3 = Service Parallel Thermoplastic, 0.060" Insulation | 18-10 AWG | 2 or 3 conductors | PVC Insulation | No Jacket | 300 V AC | Indoor Use Only
SVT = Service Vacuum Thermoplastic | 18 or 17 AWG | 2 or 3 conductors | PVC Insulation | PVC Jacket | 300 V AC | Light Usage Indoors
SJT = Service Junior Thermoplastic | 18-10 AWG | 2, 3 or 4 conductors | PVC Insulation | PVC Jacket | 300 V AC | Hard Usage Indoors
SJTW = SJT, Weather-Resistant | 18-10 AWG | 2, 3 or 4 conductors | PVC Insulation | PVC Jacket | 300 V AC | Hard Usage Outdoors
SJTO = SJT, Oil-Resistant Jacket | 18-10 AWG | 2, 3 or 4 conductors | PVC Insulation | PVC Jacket | 300 V AC | Hard Usage Indoors
SJTOW = SJT, Oil- & Weather-Resistant Jacket | 18-10 AWG | 2, 3 or 4 conductors | PVC Insulation | PVC Jacket | 300 V AC | Hard Usage Outdoors
SJTOOW = SJT, Oil-Resistant Insulation, Oil- & Weather-Resistant Jacket | 18-10 AWG | 2, 3 or 4 conductors | PVC Insulation | PVC Jacket | 300 V AC | Extra Hard Usage Outdoors
S = Service | 18-2 AWG | 2 or more conductors | Rubber Insulation | Rubber Jacket | 600 V AC | Extra Hard Usage Indoors
SO = Service, Oil-Resistant Jacket | 18-2 AWG | 2 or more conductors | Rubber Insulation | Neoprene Jacket | 600 V AC | Extra Hard Usage Indoors
SOO = Service, Oil-Resistant Insulation & Jacket | 18-2 AWG | 2 or more conductors | Rubber Insulation | Neoprene Jacket | 600 V AC | Extra Hard Usage Indoors
SOOW = Service, Oil-Resistant Insulation & Jacket, Weather-Resistant | 18-2 AWG | 2 or more conductors | Rubber Insulation | Neoprene Jacket | 600 V AC | Extra Hard Usage Outdoors
ST = Service Thermoplastic | 18-2 AWG | 2 or more conductors | PVC Insulation | PVC Jacket | 600 V AC | Extra Hard Usage Indoors
STW = ST, Weather-Resistant Jacket | 18-2 AWG | 2 or more conductors | PVC Insulation | PVC Jacket | 600 V AC | Extra Hard Usage Outdoors
STO = SThermoplastic, Oil-Resistant Jacket | 18-2 AWG | 2 or more conductors | PVC Insulation | PVC Jacket | 600 V AC | Extra Hard Usage Indoors
SRDT = Service Round Dry Thermoplastic (flat or round) | 10-6 AWG | 3 or 4 conductors | PVC Insulation | PVC Jacket | 600 V AC | Electric Range and Dryer Cords
W = Power Supply Cable | 8-4/0 AWG | 2, 3, 4 or 5 conductors | EPDM Insulation | Super Vu-Tron Jacket | 2,000 V AC | Extra Hard Usage Outdoors
S = Severe Service Cord – 600 volts (also 277/480 or 480) – May be utilized in place of SJ or SV in extra-severe service
SJ = Junior Severe Service – 300 volts (also 120 or 120/208 or 120/240 or 240 or 277, but not 277/480)
SVT = Vacuum cleaner cord, or light duty cord
T = Tinsel Cord (only if first letter of code for a portable cord)
T = Thermoplastic (if not first letter of code)
H = Heat Resistant
HH = High Heat Resistant
N = Nylon Outer Jacket Material
E = Elastomer (flexible thermoplastic that looks and feels like rubber)
O = Oil-Resistant Outer Jacket
OO = Oil-Resistant Outer Jacket and Oil-Resistant Interior Insulation
P = Parallel Cord (conductors are not twisted around each other)
V = Vacuum Cord – 300 volts (typically used with vacuum cleaners and other portable cleaning equipment)
W = Weather Resistant (UL approved for indoor and outdoor use)
W = Weather and Water Resistant (CSA approved for indoor and outdoor use)
source : https://en.wikipedia.org/wiki/Portable_cord
North American Cable Types
Nomenclature Key +
S = Service Grade (also means extra hard service when not followed by J, V, or P)
J = Hard Service
V = Vacuum cleaner cord (also light duty cable)
P = Parallel cord (also known as zip cord)—Always light duty
E = Thermoplastic Elastomer (UL/NEC designation ONLY)
O = Oil Resistant*
T = Thermoplastic
W = Outdoor—includes sunlight resistant jacket and wet location rated conductors (formerly "W-A")
H = Heater cable
VW-1 = Flame retardant
FT2 = Flame retardant
* When only one "O" appears in a classification (i.e. SJEOW), only the outer jacket material is oil resistant. If two "O's" are in the classification (i.e. SEOOW), the insulation covering the conductors and the outer jacket insulation are all oil resistant.
Definitions of Cable Types
SVT—Thermoplastic insulated vacuum cleaner cord, with or without third conductor for grounding purposes; 300V. (PVC)
SJT—Junior hard service, thermoplastic insulated conductors and jacket. 300V. (PVC)
SJTW—Same as SJT except outdoor rated. (PVC)
SJTO—Same as SJT but oil resistant outer jacket. (PVC)
SJTOW—Same as SJTO except outdoor rated. (PVC)
ST—Hard service cord with all thermoplastic construction, 600V. (PVC)
STW—Same as ST except outdoor rated. (PVC)
STO—Same as ST but with oil resistant outer jacket. (PVC)
STOW—Same as STO except outdoor rated. (PVC)
SPT-1—Parallel jacketed thermoplastic cable, 300V. With or without third conductor for grounding. (PVC)
SPT-2—Same as SPT-1 but heavier construction. (PVC)
SPT-3—Same as SPT-2 but heavier construction. (PVC)
SJE—Hard service cord, thermoplastic elastomer insulated and jacketed, 300V. (TPE)
SJEW—Same as SJE except outdoor rated. (TPE)
SJEO—Same as SJE but with oil resistant jacket. (TPE)
SJEOW—Same as SJE except outdoor rated. (TPE)
SJEOO—Same as SJE but conductor insulation and jacket BOTH oil resistant. (TPE)
SJEOOW—Same as SJEOO except outdoor rated. (TPE)
SE—Extra hard service cord, thermoplastic elastomer conductor insulation and jacket, 600V. (TPE)
SEW—Same as SE except outdoor rated. (TPE)
SEO—Same as SE but with oil resistant jacket. (TPE)
SEOW—Same as SEO except outdoor rated. (TPE)
SEOO—Same as SE but with oil resistant conductor insulation and jacket. (TPE)
SEOOW—Same as SEOO except outdoor rated. (TPE)
S—Extra hard service cord, thermoset-insulated conductors and thermoset jacket, 600V.
SO—Same as S but with oil resistant jacket. (thermoset)
SOW—Same as S except outdoor rated. (thermoset)
SOO—Same as S but both conductor insulation and jacket are oil resistant. (thermoset)
SOOW—Same as SOO except outdoor rated. (thermoset)
SJ—Hard service cord, thermoset insulated conductors and thermoset jacket, 300V. (thermoset)
SJO—Same as SJ but with oil resistant jacket. (thermoset)
SJOW—Same as SJO except outdoor rated. (thermoset)
SJOO—Same as SJ but both conductor insulation and jacket are oil resistant. (thermoset)
SJOOW—Same as SJOO except outdoor rated. (thermoset)
NOTICE: Definitions of cable designations are derived from UL's designation scheme as defined in the National Electrical Code (NEC)—NFPA-7
SOOW Product Description
The SOOW is the most popular of the portable cord category. These cables are constructed with a flexible rubber jacket, which is reliable for its resistance to abrasion and heat. The last major benefit to this construction is its cost-effectiveness.
SOOW Construction
S for Service
OO for Oil-resistant insulation and Oil-resistant jacket
W for Weather and Water resistance.
Rated to: 600 Volts
Temp. Range: -40 to 90ºC
Size: 18 to 2 AWG
Conductors: 2 to 40 Conductors
SEOOW Product Description
The SEOOW is slightly different from the other portable cables as this construction is made with a thermoplastic elastomer jacket. The biggest difference between this cable and other similar constructions is the additional chemical resistance and the rubber's additional flexible properties.
In more generic terms, Sycor's SEOOW is an engineered, high-quality flexible cord, while other similar constructions are much stiffer. The SEOOW is more resistant to water than SOOW, and it has the largest temperature from –50ºC to 105ºC.
SEOOW Construction
S for Service
E for Thermoplastic Elastomer
OO for Oil-resistant insulation and Oil-resistant jacket
W for Weather and Water resistance.
Rated to: 600 Volts
Temp. Range: -50 to 105ºC
Size: 18 to 2 AWG
Conductors: 2 to 5 Conductors
STOOW Product Description
The various constructions of the STOOW have similar resistance properties as the SOOW and the SEOOW, but not to the same extent. The main difference in this construction can be identified in the name S(T)OOW. The T stands for Thermoplastic, which actually makes the cable significantly less flexible. The STOOW construction is a reliable cable for consumer applications, portable power and lighting extensions when flexibility isn't essential.
STOOW Construction
S for Service
T for Thermoplastic
O for Oil-resistant jacket
W for Weather and Water resistance.
Rated to: 600 Volts
Temp. Range: -40ºC to 60ºC
Size: 18 to 10 AWG
Conductors: 2 to 4 Conductors
The portable and power cabling category has a wide range of constructions that are used for a variety of different industries and applications. The SOOW, SEOOW and STOOW, are very similar products that are relied on by hundreds of unique applications worldwide. With a variety of different constructions, voltage ratings and temperature ratings available, the portable power cord category has one of the widest selections of products available. Sycor is a stocking distributor of all current power cord products and has the ability to track down any obscure requests your team may have.
Source: Cord Designations UL 62 (https://www.sycor.com/blog/post/soow-vs-stoow-vs-seoow/)
What Do The Letters on the Portable Cord Mean?Portable Cord Letter MeaningsLetter | Meaning | Explanation |
S | Service | Severe heavy-duty service. These cords are portable cords with a heavy rating of 600V (size 277/480 or 480) and can be used in places like SJ or SV where abrasion resistance is needed. |
J | Junior Service | These service cords have a rating of 300V (size 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 | Refers to the material the cord jacket is made of. Thermoplastic material is light-duty and can be used as a consumer-grade portable cord. Examples: SJT, SPT, and SVT. |
E | Elastomer | Short for Thermoplastic Elastomer, a flexible thermoplastic that looks and feels like rubber. Performs better in harsh environments than thermoplastic materials. Examples: SEO/SEOW and SJEOW. |
N | Nylon | Outer jacket material. |
O | Oil-Resistant Jacket | Examples include SEO, STO, and SVO. |
OO | Oil-Resistant Insulation | Both the outer jacket and the insulation are oil-resistant. Examples: SJOOW and SOOW. |
F | Fixture Wire | These cables are rated to 90°C. Examples: H07RN-F. |
P | Parallel | This cable is parallel-jacketed, meaning the conductors are not twisted around each other. Sometimes called "zip cord." Examples: SPT. |
H | Heat Resistant | Refers to a 75°C heater cord. This is used in UL cord types like HSJ, HS, HSO, and HSJO. |
HH | High Heat Resistant | Rated for 90°C. |
V | Vacuum Cord | This is a light-duty portable cord, rated at 300 volts. Typically used with household vacuum cleaners and other portable cleaning equipment. "V" is the UL rating. Examples: SVT and SJVT. |
RD | Range or Dryer Cord | Examples include SRD, SRDE, and SROT cord. |
W | Weather and Water Resistant | UL approved for indoor and outdoor use. Examples include SEOW-WA and SJTOW-A. |
WA | Weather Resistant Jacket | A "W" means it's approved as weather-resistant (sunlight, moisture, and abrasion-resistant and can be used outdoors). Examples: SEOW and SJOW. |
North American Cable Types
Nomenclature Key +
S = Service Grade (also means extra hard service when not followed by J, V, or P)
J = Hard Service
V = Vacuum cleaner cord (also light duty cable)
P = Parallel cord (also known as zip cord)—Always light duty
E = Thermoplastic Elastomer (UL/NEC designation ONLY)
O = Oil Resistant*
T = Thermoplastic
W = Outdoor—includes sunlight-resistant jacket and wet location rated conductors (formerly "W-A")
H = Heater cable
VW-1 = Flame retardant
FT2 = Flame retardant
* When only one "O" appears in a classification (e.g., SJEOW), only the outer jacket material is oil resistant. If two "O's" are in the classification (e.g., SEOOW), both the insulation covering the conductors and the outer jacket insulation are oil resistant.
Definitions of Cable Types
SVT—Thermoplastic insulated vacuum cleaner cord, with or without third conductor for grounding purposes; 300V. (PVC)
SJT—Junior hard service, thermoplastic insulated conductors and jacket. 300V. (PVC)
SJTW—Same as SJT except outdoor rated. (PVC)
SJTO—Same as SJT but oil-resistant outer jacket. (PVC)
SJTOW—Same as SJTO except outdoor rated. (PVC)
ST—Hard service cord with all thermoplastic construction, 600V. (PVC)
STW—Same as ST except outdoor rated. (PVC)
STO—Same as ST but with oil-resistant outer jacket. (PVC)
STOW—Same as STO except outdoor rated. (PVC)
SPT-1—Parallel jacketed thermoplastic cable, 300V. With or without third conductor for grounding. (PVC)
SPT-2—Same as SPT-1 but heavier construction. (PVC)
SPT-3—Same as SPT-2 but heavier construction. (PVC)
SJE—Hard service cord, thermoplastic elastomer insulated and jacketed, 300V. (TPE)
SJEW—Same as SJE except outdoor rated. (TPE)
SJEO—Same as SJE but with oil-resistant jacket. (TPE)
SJEOW—Same as SJE except outdoor rated. (TPE)
SJEOO—Same as SJE but conductor insulation and jacket BOTH oil resistant. (TPE)
SJEOOW—Same as SJEOO except outdoor rated. (TPE)
SE—Extra hard service cord, thermoplastic elastomer conductor insulation and jacket, 600V. (TPE)
SEW—Same as SE except outdoor rated. (TPE)
SEO—Same as SE but with oil-resistant jacket. (TPE)
SEOW—Same as SEO except outdoor rated. (TPE)
SEOO—Same as SE but with oil-resistant conductor insulation and jacket. (TPE)
SEOOW—Same as SEOO except outdoor rated. (TPE)
S—Extra hard service cord, thermoset-insulated conductors and thermoset jacket, 600V.
SO—Same as S but with oil-resistant jacket. (thermoset)
SOW—Same as S except outdoor rated. (thermoset)
SOO—Same as S but both conductor insulation and jacket are oil resistant. (thermoset)
SOOW—Same as SOO except outdoor rated. (thermoset)
SJ—Hard service cord, thermoset insulated conductors and thermoset jacket, 300V. (thermoset)
SJO—Same as SJ but with oil-resistant jacket. (thermoset)
SJOW—Same as SJO except outdoor rated. (thermoset)
SJOO—Same as SJ but both conductor insulation and jacket are oil resistant. (thermoset)
SJOOW—Same as SJOO except outdoor rated. (thermoset)
NOTICE: Definitions of cable designations are derived from UL's designation scheme as defined in the National Electrical Code (NEC)—NFPA-7.
📌 Cable Code Designations (NEC Article 400 & UL Standards)(https://www.cabledatasheet.com/gallery/74_22_02_25_9_44_45.jpeg)
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🟢 Common Portable Cord Types & RatingsCode | Full Name | AWG Range | Conductors | Insulation | Jacket Material | Voltage Rating | Usage |
SPT-1 | Service Parallel Thermoplastic | 18 AWG | 2 or 3 | PVC | No Jacket | 300V AC | Indoor, light use |
SPT-2 | Service Parallel Thermoplastic | 18-16 AWG | 2 or 3 | PVC | No Jacket | 300V AC | Indoor, medium use |
SPT-3 | Service Parallel Thermoplastic | 18-10 AWG | 2 or 3 | PVC | No Jacket | 300V AC | Indoor, heavy use |
SVT | Service Vacuum Thermoplastic | 18-17 AWG | 2 or 3 | PVC | PVC Jacket | 300V AC | Light duty indoors |
SJT | Service Junior Thermoplastic | 18-10 AWG | 2, 3, or 4 | PVC | PVC Jacket | 300V AC | Hard usage indoors |
SJTW | Service Junior Thermoplastic, Weather-Resistant | 18-10 AWG | 2, 3, or 4 | PVC | PVC Jacket | 300V AC | Hard usage outdoors |
SJOOW | Service Junior Thermoplastic, Oil-Resistant Insulation & Jacket, Weather-Resistant | 18-10 AWG | 2, 3, or 4 | PVC | PVC Jacket | 300V AC | Extra hard usage outdoors |
SOOW | Service Oil-Resistant Insulation & Jacket, Weather-Resistant | 18-2 AWG | 2 or more | Rubber | Neoprene Jacket | 600V AC | Extra hard usage outdoors |
ST | Service Thermoplastic | 18-2 AWG | 2 or more | PVC | PVC Jacket | 600V AC | Extra hard usage indoors |
📌 Key to Letter Codes in NEC Portable Cords(https://www.cabledatasheet.com/gallery/74_22_02_25_9_46_23.jpeg)
Letter Code | Meaning |
S | Service Grade (Extra Hard Use, 600V) |
SJ | Junior Service Grade (Hard Use, 300V) |
E | Thermoplastic Elastomer (TPE) |
T | Thermoplastic |
O | Oil-Resistant (Single 'O' = Outer Jacket, 'OO' = Insulation & Jacket) |
P | Parallel Cord (Zip Cord, always light duty) |
W | Weather-Resistant (Outdoor Rated, Sunlight & Wet-Location Safe) |
V | Vacuum Cleaner Cord (Light Duty) |
H | Heater Cable |
VW-1 | Flame Retardant |
FT2 | Flame Retardant (Canadian Standard) |
📌 Additional Notes- Cables with "W" in their designation are suitable for outdoor use and sunlight resistant.
- "O" denotes oil resistance:
- A single "O" applies to the outer jacket only.
- "OO" applies to both conductor insulation and the jacket.
- Thermoplastic (T) vs. Thermoset Rubber:
- Thermoplastic (PVC): Lighter and less flexible, best for indoor applications.
- Thermoset Rubber (Neoprene, EPDM): Higher durability, oil and temperature resistance, used in industrial settings.
- Voltage Ratings:
- 300V: Light to medium-duty applications (e.g., household cords, office equipment).
- 600V: Heavy-duty applications (e.g., construction sites, industrial machinery).
📌 SummaryThis list includes
NEC Article 400 portable cord classifications, their properties, and typical applications. These designations are used to
standardize cord ratings, ensuring
safety and durability across different use cases.
For more details, refer to the
National Electrical Code (NEC) Article 400 and
UL Standards.