First, I don’t think it is BX.
I don’t believe that exist anymore.
Look at this.
How Installable is Your Armored Cable?
What does “flexibility” really mean for corrugated welded armored cables, and how do you know if you’re getting it?
“Flexibility in armored cable is important at installation,” says Mark Dixon, development engineer at Southwire’s Cofer Technology Center. “Flexibility is a measure of the bending the armor can take before it breaks, and the force needed to bend it – but neither UL nor the NEC address the issue.”
Industry requirements focus on post-installation protection
“UL testing focuses on the protection the armor gives after the cable is installed,” Dixon says. “The UL flexibility test simply verifies that the cable will withstand three 180o bends around a mandrel diameter 14 times the armor diameter without rupturing.”
The NEC (National Electrical Code) doesn’t define flexibility either. Section 330.24(B) only specifies that during installation, corrugated armor shouldn’t be bent in a radius less than seven times the diameter of the armor.
“The UL flexibility test doesn’t reflect installation practices in day-to-day wiring projects,” Dixon comments. “And neither UL nor NEC requirements tell whether one cable is more flexible than another in number of cycles to failure or the force needed to bend it.”
Southwire customers asked for more flexible welded armor
“Our customers were asking for a welded armor construction that would make installation easier and more reliable – so we devised testing methods to ensure that we were delivering what was needed,” says Dixon.
One Southwire test is based on the UL flexibility model, but it goes much further. A powered test mechanism bends cable samples around a curved mandrel then straightens them out again. Samples are cycled till they fail to give a performance comparison. A second test directly measures the force needed to bend an armored cable sample.
The result was Southwire’s ARMOR-Xtra™ cable. ARMOR-Xtra’s proprietary corrugation profile delivers industry leading flexibility and installation performance. In comparison testing, ARMOR-Xtra samples averaged more than 60 bending cycles before failing – over 200 percent better than the next best performer.