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How to Run Network Cables?

The best time to run your cables for a Computer Network is at the construction/renovation time. At this time it is the easiest to run cables and drill all the passage holes. If the building is already done and it doesn’t need any renovation you can still run your cables.

Fishing and Running Network Cables

For a new building, it is wise to run the cables through designated conduits and to calibrate your conduit so additional cables can be added at a later time if needed. Plan junction boxes at each floor or major node.

For an old building, installing conduits might not be possible. In this case you need to tie your cables in a bunch and secure the bunch to walls, ceiling, etc… You need to use a fish tape to fish your cables in the wall cavity. You might need to use a stud finder to avoid obstructing framing. Adjust your outlet’s position accordingly. Very often the help of a second person is needed when fishing cables, especially when you fish the cables from ceiling to the outlet, behind the wall. In this case on person feeds the fish tape down, or up depending on the case, the other person tries to catch the fish tape with another fish tape or something similar. Once the fish tape is on the position, passed through the drywall hole, attach your cables to the fish tape using duct tape. Run a pull line as well, it will be very useful in the future, in the case you want to add additional cables or replace the defective ones.

Rules for running Network Cables
Make sure before drilling any holes into joists, that you follow the building codes.
Take care of the network cable integrity:

  • do not drop objects on the cables
  • do not step on the cables,
  • do over-bend or over-twist the network cable

When you pull your cable through holes do not pull too hard as this could stretch the cable and modify its electrical qualities. Using a pull-string will provide additional firmness.
Try to avoid electric cables and other electromagnetic sources.

Cable Length and Routes

On an Ethernet type network, typically, we use a star network topology. This means that all of the devices connect into a central point, which is usually a network switch. The network switch receives and distributes all the network packets to network devices.

You need to plan your network so that the longest path from any two network devices is less than 100m, (328ft). If this is not possible plan using additional repeaters or switches. Position your network room, to obtain the least cable lengths.  

Computer Network – Tools and Supplies

Punch down tool

Punch down tool – The punch tool is used to insert the network cable in the patch panel or similar connection panels. For a small network up to 7 devices you might not need it as you can easily connect all of your devices directly into the switch.

Keystone module RJ45

Keystone Jacks – The RJ45 keystone jack is the female connector, usually immobile, part of a network connection that is mounted on the wall or similar. It provides a network connection close to the device to be connected. A patch-cord is used to connect the device to the keystone jack.

There are many types of RJ45 keystones, some require a punch down tool to be used, and some are tool-les, providing a lever for insertion and a retaining clip to secure the connection. The keystone is also produced for various categories, (Cat 3 – Cat 7), make sure you buy the correct one.


Deep Surplus
Wire Stripper Twisted Pair Cable

Wire stripper / Knife – I am not a fan of the wire stripper because it always cuts a little of the wires. Most of the times, the cut is superficial and it doesn’t get to the wire. But sometimes the stripper will scratch the wires. Using a utility knife or cutting pliers, is a little more laborious but I prefer it as I get more control. Moreover the many crimper tools come with a cable stripper. Don’t use that one, it doesn’t work for round cables, it only works for flat cables.

Simple Cable Tester

Network Tester – This is not a must, but if you are doing this for the first time, it will save you a lot of troubleshooting. For professional network cabling an expensive Network Tool that can measure attenuation, cable length, category supported, etc…, it’s a must. You need to give your client a report with your measurement results.
For small DIY jobs a simple tester will do it.


Patch Panel

Patch Panel – This is beyond the purpose of this article since it applies to bigger networks.

Network Switch

Network Switching device – The switching device switches packets between the different devices on your network. Modern switching devices can make a virtual map of all of the devices in your network and route packets according to this map.

Older connectivity devices, such as network hubs, used to indiscriminately broadcast the packets on all of the ports and only the device which the packet belonged to would have accepted it. This design creates a lot of collisions and saturates the network with unnecessary traffic.

Network hubs, (two or more ports), or repeaters, (only one port), are used to increase the maximum of 100m, (333 ft), between two devices connected on an Ethernet segment. Every repeater adds up another 100m.

Computer Network – RJ45 Connectors

RJ45 Crimped
RJ45 Crimped

RJ-45 connectors

RJ45 is a type of registered jack. The registered jack specifies the physical male and female connectors as well as the pin assignments. RJ45 features 8 pins and is the standard connector for Ethernet based networks. We can also find it on ISDN, and T1 connections. Ethernet is the standard media for the VOIP phones so we can find it used with modern digital phone systems. The RJ11 male connector, (standard telephone connector), fits perfectly into an RJ45 female connector being a little narrower, which is why many companies have deployed data networks only. The middle pair only is used for the telephone connection. There are different RJ45 male connectors for various cables.

  The male RJ45 are very cheap but they are prone to various problems.
Shielded RJ45
Shielded RJ45
The locking tab is prone to breaking. Here are some tricks to avoid this: buy the connectors with the locking tab curved down so it avoids the snagging. If you can’t find the cleverly designed connectors use boots to avoid snapping the tabs.
Snagless RJ45
Snagless RJ45

Snagless RJ45
Snagless RJ45

Snagless RJ45
Snagless RJ45

Snagless Shielded RJ45 Male
Snagless RJ45 Sheilded


There are RJ45 specially designed for solid cable, for stranded cable, for STP cable.
Rj45 Male Compare Rj45 Male Compare Use only the appropriate connector for the cable you install. Using an RJ45 for solid wire with stranded wires, or the other way around, will cause poor contacts, hence a bad connection.
Use a good quality crimper that doesn’t press on the tab when you crimp the connector.
Crimping a male RJ45 is not easy. The operation requires dexterity attention and training. If you want to make your life easier, you can use wire guides that come with some packages. Practice a lot and you won’t need the guides.
Check the “How to make a patch cord” post, for a detailed, step by step article with pictures. (coming soon)