Structured cabling, telecom, CATV, and broadband systems

Chapter 8 — Communications Systems

Structured cabling, CATV, radio/TV, and broadband. Learn ratings, separation, support, and grounding that keep low-voltage safe and compliant.

10
Major Articles
15
Quiz Questions
20
Visual Examples
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800 — Scope & Framework (Modern Article Family)

  • 800.1Chapter 8 governs communications systems (telecom/data/CATV/broadband) and can be independent of Chapters 1-7 unless they modify it.
  • 800.3Follow manufacturer listings and markings; cable type must match the space (plenum, riser, general, dwelling).
  • 800.24Mechanical execution of work applies: neat, secure, protected from damage.
  • 90.3Remember: Ch. 8 is largely independent, but other chapters can still modify requirements where noted.
EXAM TRAP
CH. 8 INDEPENDENCE
Don’t assume Chapter 3 wiring methods always apply. Chapter 8 stands alone unless another rule explicitly modifies it.
Structured cabling room
Communications systems have their own article family.
Cable listings close-up
Install per listing and space rating.
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805 — Cable Ratings (CMP, CMR, CM, CMX)

  • 805.179Use CMP in air plenums, CMR in vertical risers, CM/CMG in general purpose, and CMX where specifically permitted.
  • 300.22(C)Plenum spaces require low-smoke/low-flame cables (CMP) or listed plenum raceways.
  • ListingUse marked cable types or listed raceway/assembly evaluated for the space.
  • ReplacementIf in doubt, go one rating higher (e.g., CMP in risers)—never lower.
TABLE
Communications Cable Ratings — Quick Map
SpaceAllowed Cable TypesNotes
Plenum (air-handling)CMPLowest smoke/flame
Riser (vertical shafts)CMR (or CMP)CMP also OK
General areasCM/CMG (or higher)No plenums/risers
Dwelling limited-useCMX (permitted cases)Check article limits
Higher ratings are acceptable in lower-risk spaces; the reverse is not.
CMP jacket print
Verify jacket print before pulling.
Riser shaft
Riser-rated cable for vertical shafts.
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Separation From Power Conductors

  • 800/805.133Keep communications cabling separated from power unless separated by a barrier or in a listed assembly.
  • Raceway SharingPower and communications generally cannot share a raceway unless specifically listed for it.
  • Boxes & CabinetsUse partitions or separate enclosures when combining low-voltage with power devices.
  • Induced NoiseSeparation reduces crosstalk and conducted noise—quality and safety win.
CHART
Separation Spacing (inches)
Open runs6"
Parallel in tray2"
Barriered1"
Examples only. Follow the specific article text and listings.
Separated cable paths
Parallel runs kept apart.
Barriered box
Partition kits allow shared device boxes.
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Support, Bends, and Protection

  • 805.24Support cables with listed means; don't lay on ceiling tiles or use non-listed wires.
  • RadiusRespect minimum bend radius—protect performance and listing.
  • EdgesBushings and grommets at sharp edges or metal penetrations.
  • Physical DamageGuard exposed cabling in work areas; use raceways or sleeves as needed.
RULE OF THUMB
Protect Performance
Good workmanship = listed supports, proper radius, and protection at edges/penetrations.
J-hooks in ceiling
Use listed supports, not tie wire to grid.
Grommeted penetration
Protect jackets at metal penetrations.
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Firestopping & Penetrations

  • 300.21Maintain fire-resistance of assemblies—use listed firestop systems for the construction type and cable set.
  • 805.26Sleeves and raceways penetrating fire-rated barriers must be sealed with compatible firestop materials.
  • LabelingDocument system numbers and maintain as-builts for AHJ review.
  • Re-EntryUse re-enterable systems where frequent changes are expected.
NEC REFERENCE
Maintain the Rating
Every penetration must restore the tested fire-resistance—no foam improvisations.
Firestop around sleeve
Follow the tested system details.
Labelled firestop tag
Tagging helps maintenance and AHJ.
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Bonding & Grounding of Communications

  • 800.100Bond shields, racks, and metal raceways per article rules to the building grounding electrode system (GES).
  • SurgeUse listed protectors where outside plant enters the building—bond close to the point of entrance.
  • SDS/CoordCoordinate with power grounding to avoid ground loops and maintain effective surge paths.
  • RacksBond equipment racks, ladder tray, and cable sheaths.
TABLE
Entrance Protection — Checklist
ItemAction
Primary protectorListed device at entry
Bonding conductorShortest path to GES
Rack/Tray bondingBond to telecom busbar
LabelingIdentify protectors and bonds
Reduce surge risk and noise by bonding correctly near the entrance facility.
Telecom ground busbar
Busbar ties telecom bonds to GES.
Entrance protectors
Mount near point of entrance.
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810 — Radio & TV Antenna Systems

  • 810.15Provide a discharge unit (arrester) and bond the mast to the building grounding electrode.
  • 810.21Use the correct bonding conductor size and routing; keep it straight and short.
  • 810.18Locate the antenna and lead-ins away from power conductors and lightning exposure where practical.
  • RoofProtect lead-ins at edges/penetrations; follow listing.
RULE OF THUMB
Short & Straight Bonds
Antenna bonding conductors should be as short, straight, and direct as possible to reduce surge impedance.
Mast bond clamp
Bond the mast and arrester to GES.
Antenna entry
Protect lead-in at roof penetration.
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820 — Community Antenna Television (CATV)

  • 820.93Bond the shield at the building entrance to the GES or to the nearest accessible bonding point.
  • 820.44Maintain separations from power conductors; do not use power raceways unless specifically listed.
  • 820.100Use listed grounding blocks and protectors for outside plant.
  • SupportSupport coax at proper intervals—no ad-hoc ceiling grid support.
NEC REFERENCE
Shield Bonding Matters
Unbonded shields invite surge and noise issues. Use listed grounding blocks at the entry.
Grounding block
Bond coax to the building GES.
Coax routing
Maintain spacing from power.
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830/840 — Premises & Network-Powered Broadband

  • 830.133Cables that also power equipment must be listed for the purpose and routed with separation from power unless permitted.
  • 830.100Provide primary protection at the building entry when required.
  • 840.24Follow equipment instructions for power insertion and PoE/remote powering.
  • Fire RatingsSpace ratings still apply—CMP/CMR/CM hierarchy remains.
TABLE
Broadband Cabling — At a Glance
UseKey Requirement
Remote powerListed for power + data
Entry protectionPrimary protectors as required
SeparationFollow article rules & barriers
Space ratingMatch CMP/CMR/CM to space
When cables carry power, treat them with the same respect as power-limited circuits.
Powered node
Remote powering requires listed cabling.
PoE switch
Follow equipment ratings and loading.
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Abandoned Cable Removal & Labeling

  • 800/805 (Abandoned)Remove abandoned communications cable not identified for future use—especially in plenums and risers.
  • IdentificationLabel backbone, horizontal, and device cabling; keep records for renovations.
  • Tray/TunnelKeep pathways clear; replace broken supports before they become hazards.
  • CoordinationCoordinate with IT/owner so 'future use' actually means documented and tagged.
JOBSITE HORROR STORY
Ceiling Rat’s Nest
A renovation uncovered hundreds of feet of abandoned cable that blocked air movement and violated plenum rules—two nights of rework and tagging avoided a red tag.
Abandoned cable pile
Remove unused cable—especially in plenums.
Labeled cabling
Label now, save hours later.

Chapter 8 — Field Quick Hits

Use the Right Jacket

CMP in plenums, CMR in risers, CM in general spaces.

Keep Separation

Use barriers or listed assemblies when you can’t.

Restore Ratings

Firestop every penetration per tested system.

Bond at Entry

Protectors + short bond to the GES.

Support & Label

Listed supports, neat routing, clear labels.

Remove Abandoned

Don’t leave a rat’s nest in plenums.

Knowledge Check

Answer all questions, then click Submit Answers. You’ll see your score after submitting. Nothing is graded until then.

1

Chapter 8 rules are...

2

Which jacket is permitted in air-handling plenums?

3

Minimum jacket for vertical riser shafts:

4

When unsure about jacket rating for the space, the safe choice is to:

5

Communications and power conductors may share a raceway when:

6

At the building entry, outside-plant communications cables typically require:

7

Ceiling support best practice for low-voltage cabling:

8

Fire-rated penetrations for comms cables must be sealed with:

9

Abandoned communications cable in plenums/risers should be:

10

Antenna mast bonding should be routed:

11

CATV (Art. 820) shields at the building entrance must be:

12

Network-powered broadband/PoE cabling must be:

13

Combining power and communications in the same box requires:

14

Minimum separation goal for parallel open runs (typical practice):

15

Good documentation practice for comms cabling includes: