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Practice question · NEC 820.100
Does Coax Cable Need to Be Grounded?
Exam-style question (Sparky QOTD)
The outer conductive shield of a coaxial CATV cable entering a building must be ___.
A. grounded or bonded to the building grounding electrode system
B. connected to the neutral
C. wrapped in tape
D. left floating
Answer: A) grounded or bonded to the building grounding electrode system.
Where to Find It
Open your Code book to Article 820, section 820.100. The outer conductive shield of a coaxial cable entering a building shall be grounded — or bonded to the building's grounding electrode system.
Why It Matters
That shield is a big conductive surface running into the building from outside — lightning and surges love it. Bonding it to the same grounding electrode system everything else uses keeps the whole building at one potential. Tying it to the neutral (choice B) would put shield current on the grounded conductor; leaving it floating (choice D) leaves it as an antenna for trouble.
The Trap
Choice B preys on the “ground and neutral are basically the same” instinct. They're not — and on a communications cable, the Code is explicit: grounding electrode system, not the neutral.
Exam Tip
The communications articles (800, 810, 820, 830) each have their own grounding section, but they all end at the same place: the building grounding electrode system. Learn the pattern once, apply it four times.
Keep Drilling
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