Inside advice for outside: Tips on running LAN cabling outdoors

Good old-fashioned Cat 5e or Cat 6 network cabling has some serious advantages over WiFi as far as local area networking is concerned. For example, wired cabling is intrinsically more secure than wireless networking as it requires some sort of mechanical intervention to eavesdrop on or perform a man-in-the-middle attack against. LAN cabling can also carry a much higher bandwidth for data transmission than your run-of-the-mill, garden-variety WiFi network. A wired network is also much more resistant to electromagnetic interference than WiFi as this article from NetworkWorld explains.

On the other hand, there are certain situations where you might obviously prefer a wireless network solution than laying down some twisted-pair network cables. One of the more obvious of these is when installing a cable would involve ripping up flooring or knocking sizeable holes in your walls. Hey, why didn’t they design houses with false ceilings or floors? I don’t know.

Another problem with wired cabling is when you need to run it outdoors, for example to connect two buildings together in a campus or connect an outdoor CCD security camera to your home security system. WiFi networking is the most common way of solving these kinds of problems, but as I said it might not be the best approach depending upon your constraints (with security being the primary consideration). Let’s take a brief look at some of the ways you can approach the problem of running LAN cabling outdoors.

Go for direct burial

If you need to run a network cable outdoors for any appreciable length, you’ll probably want to bury it instead of hanging it in the air where birds can peck on it and the elements can work their damage. For this purpose you’ll need to obtain some direct burial cabling, which comes in various grades from Cat 5 through Cat 6.

Direct burial cables are made with a special insulating jacket composed of either polyvinyl chloride (PVC) for the cheaper variety, or the better Linear Low-Density Polyethylene (LLDPE), which has strong protection against impact so it won’t be punctured and is highly resistant to deterioration even in harsh environments. These cables are generally filled with a special gel for moisture protection or have their twisted pair wires wrapped with a special water-resistant tape. They’re also usually shielded for extra protection from RF interference, and they’re available from a wide variety of vendors including Amazon though I prefer the types available from Structured Cable Products. Monoprice is also a great place to look for good deals on bulk outdoor network cabling.

Laying down a conduit

While simply burying a cable can be a workable solution, it’s often better if you also use a conduit for your cable run. While laying down a conduit properly does mean you can avoid the added cost of needing direct burial cabling, it’s always best to use such cabling instead of the cheaper and less durable indoor Cat 5e cabling because conduits can fail under harsh environmental conditions like heavy rainstorms.

In addition to providing extra protection for your cabling, the other basic advantage of a conduit is that you can easily run more cables if you need to. If you need to pull an additional network cable through a conduit that already has other cables in it, the simplest way is usually to attach and use a string to pull the new cable — provided, of course, that you can get the string through the conduit. Of course, it would make sense to leave a string in the conduit when you bury it in the ground.

Advice is always best when you consider it before you get started. So what if you’ve already buried your conduit and pulled a cable through it, and you need to pull another cable through your conduit and you didn’t leave a string in the conduit? One tip I’ve heard from some of my geeky colleagues is to try attaching a vacuum cleaner hose to the far end of the conduit and suck the string through. Bill Bach, one of the regular readers of our popular weekly IT pro newsletter WServerNews, amplifies this tip with the following suggestion which he has himself used on certain occasions: “Sometimes the vacuum can’t pull the string through the conduit because the conduit is open at the end and much of the suction is lost. This issue can be solved by adding a small bit of plastic bag to the string with a tight knot. The amount of plastic needed may depend on the size of the conduit, how much free space there is, and so on. This seals up the end of the conduit, allowing the suction to be applied to the plastic bag and connected string and pulling it through much more easily.”

Alternatively, you can avoid the “how to pull” problem entirely by running some extra unused cabling when you install the conduit. After all, if you’re going to all the trouble of digging up a trench and installing a conduit, adding a few more cables into the conduit is probably going to mean only an incremental increase to the overall cost of your outdoor cabling project.

Using your HVAC conduit

Many buildings and campus environments already have a system of HVAC conduits in place. How can you leverage this existing conduit system for laying down some Ethernet cabling through it? One colleague suggests using a string, some washers and some fish tape. You start by turning off your furnace and air-conditioning system including any fans used in the conduit. Tie some of the washers onto one end of a string to make a “pull string” and locate the duct that is nearest to the “up tube” of your system. Then tie the rest of the washers to another piece of string that will be your “drop string.” Also, tie the fish tape to your drop string using a slipknot. Now push the fish tape along until you reach the up tube.
It helps to have someone watching the up tube to let you know when you’ve reached it. Now pull the drop string that has the slipknot to drop the washers with the pull string attached to them. If you did this right, your pull string will case out until it hits the bottom. Once you’ve figured out where it landed, use the fish tape to hook the pull string and then use the pull string to pull your network cabling through the system.

Don’t forget

One final tip to make your life easier. Don’t forget to test your cabling before you bury your conduit or go through the effort of snaking around your HVAC system. The last thing you want to do is expend a lot of blood, sweat, and tears laying a network cable outdoors only to find out afterward that the cable has a flaw or doesn’t perform as well as you expected. Test your cables for connectivity before, during, and after you install them in the ground, in a conduit, or in your HVAC system. And don’t just use a simple Ethernet testing tool with blinking lights; be sure to use a tester that can actually determine the transfer speed you’re getting in your cable. I’ll look at some good Ethernet cabling testers in a future article here on Techgenix.

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