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In a previous question, I had planned a Cat6 (Ethernet) cable run outside a home, adjacent to a coax run. I was advised against it, and I'm interested in taking that advice.

Now I'm considering running the cable inside an exterior wall. (I mean running it inside a wall which separates the house from the outdoors.) It will go from the basement to the 2nd floor.

Questions:

  1. Once installed, is this "safe" in terms of lightning and surge considerations? Does the single wall actually add a significant amount of insulation in addition to the miles of air gap between the house and the clouds?

If it's a reasonable approach...

  1. Does it matter if the cable is shielded or not? If shielded, should the shield be grounded?

  2. What additional protections should I add? Like types and locations of surge protection, etc. I'd like to protect the equipment at both ends, but one is more valuable than the other.

cp.engr
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The standard would dictate you do not run a cable inside a wall without putting it into a pipe (conduit), however this is often done. You're talking of home installation here, not professional office so that is not uncommon to find.

Generally, by experience, you won't have issues with that, even with an exterior wall. Assuming your house has an operational lightning rod and that the ground cable is not right there next to your network cable.

However, also by experience, I have had many computer which had their network card fried through surges dissipating through the network cables running in the walls. They must have picked up the surge through contact with other metal structures in the wall or other wires since the lightning hit the side of the building (the lightning rods weren't operational).

If your cable goes outside the building, then it should be outdoor cable and have a surge protector at both ends which is well grounded. If it runs inside the walls, then you can take the risk. Might not follow the building code of your area. It might never cause problems.

ETL
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Answer to questions is found in concepts introduced in elementary school science. Lightning seeks earth ground. An electrically shorter path to earth is via a wooden church steeple. Because wood is a better electrical conductor.

Why is an ethernet cable better protected by wooden (plywood) walls? Same reason.

Now that is a direct strike to the structure. What protects direct strikes to appliances? A direct strike to utility wires far down the street is a direct strike incoming to all household appliances.

To protect the wooden structure, earth a lightning rod. So that earth ground protects the structure. To protect internal appliances and ethernet cables, earth a 'whole house' protector. So that earth ground protects everything inside the building.

One a surge is permitted (by humans) to be inside, then that surge will hunt for earth ground destructively via appliances. Nothing inside the building will avert that destructive hunt. You must connect that surge (ie lightning) to earth BEFORE it can enter. For the same reason that Ben Franklin's lightning rod kept lightning from conducting to earth destructively via wood.

BTW, that is earth ground. Not safety ground provided by wall receptacles. If a surge is not earthed BEFORE entering, then nothing will avert the destructive hunt. As has been understood and demonstrated for over 100 years. Appliance damage indicates a human made a mistake.

westom
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