Grounding Your Coax: What NEC-810 Requires and Why It Matters
The National Electrical Code (NEC-810) requires all coaxial cable shields to be grounded at the point where they enter your home. This ground connection should tie into your home’s main electrical ground to create a single, unified grounding system.
Why ground the shields?
The goal is to bring the cable shields as close to zero volts (earth potential) as possible. When everything is at the same potential, there’s no voltage difference to drive current flow—that’s basic Ohm’s law. This helps prevent common-mode currents from traveling on your coax shields.
The reality: no ground is perfect
A single ground rod doesn’t achieve a true zero-ohm connection to earth, so some common-mode current can still flow on the shields. This is where a Common Mode Choke (CMC) helps.
What a CMC does
A CMC presents high impedance to common-mode currents at RF frequencies, blocking them from traveling down the cable. It’s an extra layer of protection that works alongside proper grounding to keep RF out of your shack and reduce interference.
Take a moment and watch this excellent video about station grounding and more. While Dave’s video mostly addresses possible concerns for US radio amateurs, you can also view this excellent publication by RSGB, which applies to most European amateur radio installations.
See the following links as well for supplementary info regarding any grounding and code/safety guidelines :
- ARRL.org- Electrical Safety and Grounding Article
- NEC 810 code for grounding
- CTU- Grounding for a HAM radio station
- Grounding presentation
