My company needs to create a network link between two buildings.

Currently we have a cat5e network in one building and would like to connect some computers(about 15) in our second building to the main network in the first building.

The distance between the two buildings is 30 metres. The 30 metres means going through a wall from the first building. Going through the car park and then through a wall into the other building. We can run any cables through speed ramps and so we do not need to dig up the road!

Also the second building does not have an Internet connection and so we have to create some sort of cable link so that they can share our Internet connection.


Should we just run cat5e?

Should we run fibre?

Should we run coaxial?


Definitely go with fiber.

The two buildings most likely don't have a common ground. Running anything with an electrical connection such as a CAT5 cable across that takes a risk of electrical surges due to the difference in grounds. I've seen a lightning strike one building and take out everything connected to a network in another building b/c they were linked via a cat5. It killed a lot of switches and network cards. Maybe modern switches do more to protect against this as this was a long time ago. But I wouldn't risk it.

Also with fiber you can also upgrade the speed to 10GBit in the future.

Also while you're running the lines run a couple of spares if you can. No matter what you choose to go with.

  • 1
    +1 trunking fiber is my first choice. – Warner Mar 25 '10 at 18:16
  • Thanks - Could you supply links to switches, fibre channels and fibre which you would recommend? – Adam Chetnik Mar 25 '10 at 18:17
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    +1 - I have seen copper wiring (coax, cat5, etc) take out all sorts of gear from lightning strikes as well. Fiber is the way to go, worst case, he could use transcievers at either end to convert to copper at switches. – Kevin K Mar 25 '10 at 18:20
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    UTP-based Ethernet isn't susceptible to ground loops, to my knowledge. You should definitely use lightning arrestors, though, any time you egress a building with a metallic cable. – Evan Anderson Mar 25 '10 at 18:20
  • Definitely run spares. – Joe Mar 25 '10 at 18:33

Either category 5e/6 copper or fiber would be your best bets. There's no good application for co-axial cable with modern commodidy data networking.

Fiber is nice because you don't need lightning arrestors, but it's a more costly cable to terminate than copper. Multimode fiber would be my choice, since it's a lot cheaper to terminate than single-mode fiber. For that kind of distance, the 10GBASE-LRM standard allows 10GB Ethernet, in the future, over multimode fiber.

Your distance is short enough that copper is feasible. You definitely need to use lightning arrestors. UTP-based Ethernet doesn't suffer from ground loop problems.

Both copper and fiber will do gigabit Ethernet fine, and with the number of users you're talking about in the "remote" building, feeding their entire network with gigabit Ethernet ought to be fine.


A physical connection fiber/wire will almost always be better from the perspective of functionality and performance.

OTOH another inexpensive option might be to just setup a point to point wireless connection. A wireless connection using recent technology should be able to provide between 50-150 MB of bandwidth and seems like it should be enough for 10-15 people using computers for typical office functions.

  • 2
    I've done a few installations for wireless between buildings and I would say unless you're buying high end equipment it isn't worth it. Especially since the OP said they don't have a problem running a cable. – einstiien Mar 25 '10 at 19:34
  • I've run a building-to-building wireless link at my church for years using commodity equipment. – Keith Stokes Mar 26 '10 at 0:31
  • What does OP stand for?! :))) – blank3 Mar 28 '10 at 20:22
  • @blank3, OP - Original Poster. In this case, the person who asked the question. – Zoredache Mar 28 '10 at 21:16

I vote fiber. You can use MM and for 30 meters it is cheap. As has been mentioned connecting copper between separate buildings is a recipe for disaster (ask me where I got shocked).

WIFI, commercial quality, is also not a bad option. My ISP uses it to hook-up rural users (me). I am three radio hops away(30 miles) from the ISP's POP and get good service.


Fiber is going to be expensive. I would recommend going with copper as a first step. With copper (ethernet) you've already got the infrastructure in place (I'm assuming that the other building already has plant wiring, a switch, etc). The only implementation costs is going to be for a copper cable run from one building to the other. If you go with fiber, you're going to have to pay for the fiber cable, installation and qualification, new switches and\or fiber interfaces for the current switches if they support fiber, etc.

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