Compression Couplings or Set-screw Fittings?

While meeting with electrical contractors and fire-alarm vendors during my travels, great discussion surrounds electrical circuit integrity systems and meeting and maintaining UL 2196 & NFPA 72 code compliance. Radix Wire’s DuraLife 2-Hour fire-resistive cables are certified for 2-hour circuit integrity, which means they meet the pathway survivability circuit requirements in the NFPA 72, but the hardware system seems confusing. Let’s take the opportunity to review three of the most common challenges seen in the field regarding certified hardware components.

Today, we’ll focus on compression couplings versus set-screw fittings. In the next article of this three-part series we’ll discuss metallic raceways, and finally we’ll touch on splicing and the usage of connectors inside of the fire zone.


According to the UL-published FHIT.28A & FHIT.28B, Radix Wire’s DuraLife-W (wet-rated) and DuraLife FPL (dry-rated) cables must be installed utilizing only certified hardware materials. Our specification sheets currently reference enclosure set-screw fittings from Hubbell-Raco, as well as compression fittings by Cooper Crouse-Hinds.


Either one has worked for us in the past; which do we need to use and when?


While both materials are typically interchangeable in the field, Radix Wire specifically certified Hubbell-Raco set-screw fittings to connect raceways to boxes. Only! Whereas Cooper Crouse-Hinds compression fittings are intended to connect metallic raceways together, and connectors are used for splices – but we’ll get to that last one later.

For more information and to ask all of your installation questions, please feel free to contact me directly at 216-400-6719. Stay tuned next week for a Q & A on metallic raceways and why EMT must be used. Thank you!

Eli, the CI Guy
(216) 400-6719