Extension Cord Elmo Tips – Extension Cord Codes

Extension Cord Codes – What Those Markings Really Mean

The Jackets of extension cords are covered with imprints or embossing indicating how and where they can appropriately be used.

It is essential to choose the correct cable jacket if you plan to use the extension cord in a demanding environment.

Here’s the key to some of that code as outlined in the National Electrical Code.

Extension Cord Key

SHard Service Flexible Cord
SJJunior Hard Service Flexible Cord
EThermoplastic Elastomer Insulation
TThermoplastic Insulation
OJacket is Oil Resistant
OOJacket & Conductors are Oil Resistant
RThermoplastic Rubber Insulation
XCross-linked Synthetic Polymer Insulation
HHHigh Temperature
WMoisture Resistant
NNylon Jacket