Cabling Requirements

Cabling requirements

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Doing It Right... The First Time

Here is an example of taking a proactive approach to computer networking. The idea for this manufacturing plant's offices was to anticipate all necessary wiring in advance, at the time the building was constructed. Every office was given at least two "standardized computer network drops".

As seen in the photo below, these consisted of two Ethernet ports (blue), one phone jack (a green RJ-45 socket), and one modem jack (a red RJ-45 socket). Since a computer, FAX machine, or printer would be located here, these "standardized drops" would include an isolated-ground power outlet for computer equipment, and a regular power outlet for anything else.

Medium- to large-sized rooms were wired with three or four drops. This allowed for a great deal of flexibility in future expansion of the office staff. Conference rooms typically had four drops, with extra regular power outlets interspersed. This allowed up to eight sales people and engineers to bring their laptops, connect online and all work as a team.

Advantages of this system:

	The cost for providing this comprehensive standard upfront was estimated to be far less than the cost for paying a network installer to run new cables as needed.
	The sequential number labeling of the network drops made the technical support documentation simpler.
	The installation carried out during the construction phase resulted in a much neater, uniform appearance.
	The delay and inconvenience of retro-cabling when offices are occupied could be avoided.

A typical network drop as connected.

Always with corporate expansion in mind, extra facilities were provided. Below is a photo of cored holes leading from the computer room on the second floor, to the first floor office area. Eight four-inch holes were drilled, and electrical conduit pipes installed to provide a way for wiring to pass between floors.

The seventh hole is partially filled, while the eighth hole is purposely left vacant for future needs. The white cables are for the computer network (UTP, plenum rated, FT6). The gray cables are for phone and modem (plenum rated, FT6), and for security system cameras and proximity sensors. Difficult to see here is red serial network cable which is used with the timeclock system.

Avoiding electrical interference near power lines. The Ethernet cables are required to cross close to numerous 600 Volt high current power lines, when they enter the plant area. To prevent induced currents in the copper network cables two four-inch conduit pipes were installed at 90 degrees to the power lines. The power lines can be seen as seventeen thick black cables running in parallel diagonally across the first photo:

Conduit Pipes to the Plant.
Crossing 600 Volt High Current Power Cables.

The two pipes were fastened to the metal ceiling pan, and were grounded to the office isolated-ground. The coaxial antenna cable from the Ethernet bridge and the network cable for the wireless barcoding transmitter are run through these pipes.

Robust, well protected hardware installations. When there is some concern about possible damage to network cabling, two-inch or four-inch metal conduit pipes are used to protect the relatively delicate wire.

Protecting Ethernet cables, and accessing rooms below.

In the photo above, the network cabinet is to the right, in the second photograph. It is a double hinged, lockable, wall mounted cabinet, with its own isolated-ground power supply. The network switch and hubs are plugged into a dedicated UPS.

The switch has a fibre-optic module, and the fibre run links it back to the computer room. The orange innerduct can just be seen above the network cabinet. For an extra measure of protection, the innerduct tubing is fastened to the inside of the I-beam column, as it rises to the ceiling pan.