Allied Encyclopedia – STJ Cable vs. SFJ Cable

Allied EncyclopediaThere are so many cables available on the market today that even simple variations in materials or construction can create almost identical cables with completely different names. This can make finding the right cabling solution difficult, especially if you are having trouble pinpointing the differences between one cable and another. Today, we’ll look at STJ cable and SFJ cable. They have almost everything in common, but recognizing their differences could make identifying the right cable for your application a little easier.

STJ cable and SFJ cable share the same usage ratings. They are 600 volt cables with temperature ranges of -65°C to +200°C. Both are MIL-W-16878D Cables with M16878/4 Type E NEMA HP3 inners. With all of these ratings and specifications in common, there is no doubt that these cables are very similar.

When we break down the construction and materials used in each cable, we see even more common features. Each cable is available in single or multi-conductor versions.  The conductors are made with silver-plated copper, feature Type E extruded PTFE insulation, and have an overall silver-plated copper braid shield with 90% coverage.

STJ Cable

STJ Cable – 14 AWG with 6 Conductors

Now you’re probably getting confused. Are these the same cables? That wouldn’t necessarily be surprising, considering the industry’s tendency to identify a cable by multiple standards or names, so long as the cable itself meets or exceeds each individual specification. However (fortunately), that is not the case here.

Although the names and ratings used in the wire and cable industry can be confusing, there is an obvious difference between STJ cable and SFJ cable: jacket material. STJ cable has an overall sintered wrapped PTFE tape jacket. SFJ cable, on the other hand, has an overall extruded FEP non-stick jacket.

Despite their different jacketing materials, both cables resist acids, alkalis, oil, flame, moisture, solvents, and fungus. Both are also non-reactive and exhibit low friction properties. That’s because PTFE and FEP are very similar polymers. Feel like we’re back to square one? Don’t.

SFJ Cable

SFJ Cable – 24 AWG with 4 Conductors

Generally, SFJ cable’s FEP jacket is softer than PTFE. It is also transparent, very sunlight resistant, and has a lower melting point. It has slightly lower tensile strength than the PTFE used in STJ cable, but it is also a little more flexible and more abrasion resistant. Finally, FEP has a higher dielectric strength and dissipation factor, but lower resistivity than PTFE.  SFJ cables also tend to be slightly more expensive than STJ cables as well. Though these may not seem like huge differences, they may be the characteristics that decide whether you choose STJ cable or SFJ cable for your application.

To learn more about STJ Cable and SFJ Cable, visit the STJ and SFJ section of the AWC online catalog.

About awcwire
Allied Wire & Cable is a value-added manufacturer and distributor of electrical wire and cable, tubing, and more. We are a family owned and operated company, serving a wide range of industries, including the military, automotive, aerospace, and telecommunications markets. Allied is headquartered in Collegeville, PA. Additional locations can be found across the US, in Phoenix, AZ; Bedford, NH; Pewaukee, WI; Rochester, NY, Tampa, FL; and Mt. Juliet, TN. For more information on Allied, visit our main website at

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