I'm going to have a network cable run between floors of a home, and most of the run will be outdoors, up the side of the building. I ordered a spool of shielded UV-rated waterproof Cat6 cable.

From what I've read, I should ensure that if any part of the run is parallel to electrical / power lines, there is at least ~6" - 8" separation. And I need to watch that the minimum bend radius for the length of the run is > 4x the outside cable diameter.


  1. Should the shielding be grounded somehow? Or is it enough to just serve as EMI shielding? (I don't know yet if the cable has a drain wire.)

  2. I would like to protect the equipment at both ends from surges / lightning strikes (to the extent possible). Is an Ethernet surge protector at one end of the cable sufficient? Would putting them on both ends create a ground loop?

  3. Is the risk of damage from lightning strike any different from an outdoor coax run?

  4. Any other hazards that I should consider?

EDIT: In light of the advice received here, I'm considering a different approach.

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    Ditch the copper and run fiber. That's the only responsible thing to do. – EEAA Jun 22 '15 at 1:08
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    @EEAA, please elaborate. Why is that "the only responsible thing"? I only want a LAN connection, and don't want to purchase the extra equipment (e.g. transceivers), nor to deal with fragile fiber. – cp.engr Jun 22 '15 at 1:14
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    A surge protector is going to do nothing to protect your equipment, nor is shielding. It doesn't even take a direct strike to do damage. One lightning strike within half mile or so will induce enough current to destroy whatever equipment you have on either end of the cable. You asked your question on a site for professionals, so you're getting a professional answer. Fiber isn't always about speed. In this case, you don't need the speed, but you do need a cable that isn't susceptible to EMI. Fiber is your answer. – EEAA Jun 22 '15 at 1:18
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    Several sites where copper was used between buildings, inside steel cable, with surge suppressors, where ICs were blown clear off of switch PCBs on both ends of the run. Various other situations where equipment was not physically damaged, but was dead nonetheless. It's plain just not worth the risk. Running fiber once is cheaper than running copper twice and re-purchasing equipment. – EEAA Jun 22 '15 at 2:06
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    I don't understand why, with so little domain experience you are even thinking of doing this yourself. You should hire a local cabling contractor. They will be able to advise you of the correct way to do this while staying within the bounds of the local building/electrical codes. – user9517 Jul 6 '15 at 9:51

Telco COs suffer about 100 surges with each storm due to copper wires all over town. How often is your town without phone service for four days after each storm while they replace that $multi-million computer? Never. You must do what they do.

Your concern is for a direct strike that hunts for earth destructively via interior appliances. That ethernet wire is exposed - not protected by something that is lightning conductive - wood. So use another proven technique. A lightning rod (and this is what actually does the protection) connected to an earth ground means an ethernet wire below is unlikely to be a victim of a lightning strike. Any lightning that seeks earth will use the lightning rod and not your exposed ethernet wire.

Protection from lightning is routine. But that means understanding a fundamental question. Where do hundreds of thousands of joules harmlessly dissipate? A lightning strike far down the street means lightning is incoming to every household appliance. Your TV cable has a hardwire that connects that cable low impedance (ie 'less than 10 feet') to single point earth ground. That means a surge connects to earth BEFORE entering the building. That means hundreds of thousands of joules dissipate harmlessly outside in earth.

Telephone and AC electric cannot connect directly to earth. So we (and that telco CO) do what has been proven by over 100 years of science and experience. Connect every wire inside every incoming cable to earth directly or via a 'whole house' protector. Again, protector does not do protection. Earth gruond absorbs that energy. Protector is only doing what that TV cable's direct hardwire connection does better.

That is the point. How does a surge current get to earth. Either harmlessly outside. Or it goes hunting for earth destructively via appliances.

Ethernet shield is for noise. Would be grounded at one end to a chassis of that appliance. Should lightning strike the shield, then lightning is connected destructively to earth via that appliance.

For a shield to provide tiny surge protection protection, it must connect a completely different ground - earth ground. An ethernet shield first must drop down to the single point earth ground to make a low impedance (ie 'less than 10 foot') connection to earth BEFORE entering the building. Surge protection is always about how that surge current connects to earth.

What would an ethernet protector do? Is is connected low impedance (hardwire with no sharp wire bends) to single point earth ground? If not, then it only protects from other surges already made irrelevant by protection inside all ethernet interfaces.

Appreciate the many electrically different grounds. Chassis ground is completly different from a wall receptacle safety ground; is completely different from earth ground. All may be interconnectded and are still electrically different grounds. Term 'low impedance' makes that obvious.

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    I appreciate your time and effort. There is definitely some good info in your answer, but there are too many sentences that I can't parse for me to accept it. – cp.engr Jun 26 '15 at 2:19
  • So only read only the first paragraph - and no more. Grasp or ask questions about that paragraph: Telco COs suffer about 100 surges with each storm due to copper wires all over town. How often is your town without phone service for four days after each storm while they replace that $multi-million computer? Never. You must do what they do. Move on the next paragraph only after learning what the first paragraph says. – westom Jul 1 '15 at 19:19
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    My questions start after the first paragraph. I think it would be a discussion best suited for chat (not comments), which I don't have enough rep for. – cp.engr Jul 3 '15 at 16:29
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    So I am confused. What part is too vague or confusing? What do you not understand? What an earth ground is? What lightning seeks to do damage? How surge do damage by finding earth via appliances? What Franklin demonstrated in 1752? None of this stuff is technically complicated. Something understood in a first reading was already known. Things that are new are never understood until a third reread. – westom Jul 4 '15 at 16:56

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