While doing my own research (going through 2020 and 2023 codes) on the interchangeability of NM-B and UF-B cable indoor and the ampacity of 60C vs 90C, I stumbled upon yet another issue, flame retardant. The UF-B wire (atleast the Southwire) doesn't have flame retardant certifications. Then I went to check the UL standards in both the NM-B and UF-B cables listed at Sourthwire.com (same wires listed at Homedepot with pdf spec sheets) and the only difference between the two was UL 719 and UL 493, which i'm not sure covers flame retardant. UL 83 listed on both cables might have some flame/smoke properties per UL 83 point 5.12.
I would prefer to use the flame retardant wire indoors so I did some more research. The plot thickened because I found two separate spec sheets for the 12/2 NM-B cable at southwire.com and other at cabletechsupport.southwire.com. The NM-B cable listed at cabletechsupport.southwire.com had additional fire certifications but missing (or not printed on the same cable at southwire.com). The stock# of both cable is same #288282. Fire specs only apply to larger cables which generally are not found in homes/indoors. So the question remains is NM-B cable 12/2 or 10/2 has flame retardant and UF-B doesn't?
Reference links are below.
UL 83 5.12
https://www.intertek.com/standards-updates/ul-83-thermoplastic-insulated-wires-and-cables/
NM-B cable with fire certifications Spec 10029
http://cabletechsupport.southwire.com/en/tile/30/cable/25634/?country=US
- ASTM B3 Standard Specification for Soft or Annealed Copper Wire
- ASTM B8 Concentric-Lay-Stranded Copper Conductors
- ASTM B787 19 Wire Combination Unilay-Stranded Copper Conductors
- UL 719 Nonmetallic-Sheathed Cables
- UL 1685 Vertical-Tray Fire Propagation and Smoke Release Test (1/0 and Larger)
- UL 2556 Standard for Safety Wire and Cable Test Methods
- ICEA S-95-658 (NEMA WC70) Power Cables Rated 2000 Volts or Less for the Distribution of Electrical Energy
- IEEE 1202/FT4 Flame Test (70,000 BTU/hr) 350kcmil and Larger
NM-B cable without fire certifications
https://www.southwire.com/wire-cable/building-wire/romex-brand-simpull-type-nm-b-cable/p/BW7
Southwire Romex® Brand SIMpull® NM-B cable complies with the following:
- Listed per UL Standard 719
- UL 83 (Conductor Construction)
- ASTM B-3 and B-8
- Federal Specification A-A-59544
- National Electrical Code, NFPA 70
- REACH/RoHS Compliant
