Cable Installation Practices
Plenum and riser ratings, bend radius rules, conduit fill, pull tension, cable management, and pulling techniques.
- Identify fire ratings CMP, CMR, CM, CMG, and LSZH and where each is required
- Calculate minimum bend radius for UTP and fiber cables
- Apply NEC conduit fill percentage rules
- Describe pull tension limits and proper pulling techniques
Lección 1
Fire Ratings - CMP, CMR, CM, CMG & LSZH
Cable Fire Ratings for Copper
The National Electrical Code (NEC) Article 800 mandates specific fire ratings for communications cables based on the installation space. Installers must select the correct rating to pass inspection and protect building occupants.
CMP (Communications Plenum) cable uses low-smoke jacket compounds (typically FEP or LSZH) that pass the NFPA 262 flame and smoke test. Plenum spaces are areas used for air circulation - above drop ceilings and below raised floors connected to the HVAC system.
CMR (Communications Riser) cable passes the UL 1666 vertical flame test. It is required in vertical shafts connecting multiple floors.
CM (Communications) and CMG (Communications General) cables are general-purpose ratings for horizontal runs on a single floor in non-plenum, non-riser spaces.
Substitution Hierarchy
CMP can substitute for CMR, CM, or CMG. CMR can substitute for CM/CMG. Always use equal or higher rated cable - never substitute a lower rating into a space requiring a higher one.
LSZH Cable
Low Smoke Zero Halogen (LSZH) cable uses jacket materials that produce minimal smoke and no toxic halogen gases when burned. LSZH is required in many international installations, military facilities, subway systems, and marine environments. LSZH is not a direct NEC plenum substitute but meets IEC 60332 standards.
CMP Plenum
NEC recognized
Low flame spread
Low smoke
Required in US plenums
LSZH
IEC standard
Zero halogen emissions
International standard
Transit and marine use
CMP is the highest copper cable fire rating, required in plenum air-handling spaces. CMR is for riser runs between floors. Higher-rated cable can substitute for lower, but not the reverse. LSZH is the international standard for low-smoke, halogen-free installations.