Flexible cord letters explained: SJT, SJTOW, SJOOW, SOOW, SEOOW

The letters

Letter	Means	In practice
S	Hard service	600 V rated; the heaviest jacket, for portable power, construction and industrial equipment.
SJ	Junior hard service	300 V rated; the everyday tool, appliance and shop-equipment cord.
SV	Vacuum / light duty	300 V, thin jacket, light appliances only. Not stocked here.
T	Thermoplastic (PVC) jacket	Stiffer and cheaper than rubber; the SJT family. Rated 105 °C on most of ours.
E	Thermoplastic elastomer jacket	A rubber-like plastic: flexible in the cold, lighter than true rubber.
O	Oil-resistant jacket	The outer jacket shrugs off oil; the conductor insulation does not.
OO	Oil-resistant jacket and insulation	Both the jacket and the conductor insulation resist oil — machine areas, hydraulics, food plants.
W	Weather and water	Rated for outdoor use and wet locations, sunlight-resistant jacket.

Put together

Type	Jacket	Rating	Reads as
SJT	PVC	300 V	Junior hard-service thermoplastic
SJTW	PVC	300 V	Junior hard-service thermoplastic, weather-rated
SJTOW	PVC	300 V	Junior hard-service thermoplastic, oil-resistant jacket, weather-rated
SJTOOW	PVC	300 V	Junior hard-service thermoplastic, oil-resistant throughout, weather-rated
SJOW	Rubber	300 V	Junior hard-service rubber, oil-resistant jacket, weather-rated
SJOOW	Rubber	300 V	Junior hard-service rubber, oil-resistant throughout, weather-rated
SJEOW	Rubber	300 V	Junior hard-service elastomer, oil-resistant jacket, weather-rated
SOOW	Rubber	600 V	Hard-service rubber, oil-resistant throughout, weather-rated
SEOOW	Rubber	600 V	Hard-service elastomer, oil-resistant throughout, weather-rated
H05VV-F	PVC	300/500 V	Harmonized PVC flexible cord (HD 21.5) — indoor appliances and equipment
H07RN-F	Rubber	450/750 V	Harmonized rubber flexible cord (HD 22.4) — outdoor, heavy duty, site power
UNIV	PVC	300/500 V	Universal PVC cord listed UL / CSA and HAR-marked — one reel for both markets

Reading one

SJTOW: SJ junior hard service (300 V), T thermoplastic PVC jacket, O oil-resistant jacket, W rated for weather and wet locations. The everyday shop cord. SOOW: S hard service (600 V), OO oil-resistant jacket and insulation, W weather. The portable-power and construction cord. The difference between the two is not toughness alone; it is the 300 V ceiling on every SJ type.

What the letters do not say

Gauge and conductor count. Those come first on the label — 14/3 SJTOW is 14 AWG, three conductors — and they are what the ampacity table and the voltage-drop rule decide.

Read the jacket before you buy it

The letters

Put together

Reading one

What the letters do not say

Every reel, by its letters