SOT - Att 3 - SOCAMES 6 Design Alert 1 - Miami Infra - 546 20 120.pdf

HEFP/10NA5G/29APR20

SOCAMES 6 Design Alert 1

Problem

During a recent construction activity of cable upgrades to an existing telecommunication room (TR) at an Initial Operating Capability (IOC) site, it was discovered during cable testing procedures that some of the cables being upgraded were greater in length to the end user device than standards allows.

Background

ANSI/TIA-568.D, “Balanced Twisted-Pair Telecommunications Cabling and Components” (Sep 2018) version of industry standards for telecommunication room fixed cabling installation, limits the total length of a network Unshielded Twisted Pair (UTP) cable segment to 100 meters. The 100 meters is broken down as 10 meters for patch cables and 90 meters for total fixed cabling. Cable length requires a three-dimensional assessment to ensure that the fixed cables being installed do not exceed the specified UTP cable segment of 90 meters of fixed cable length.

There are several scenarios that require an assessment to occur to ensure that a telecommunication rooms UTP cable segments do not exceed 90 meters.

Scenario 1: The installation of a new telecommunication room to serve an area.

Scenario 2: The relocation of an existing telecommunication room to serve an area.

Scenario 3: The installation of new cabling upgrades in a telecommunication room that will remain in place to serve an area.

Scenario 4: An existing telecommunication room that will not receive any cabling upgrades.

Solution

To ensure that an assessment is performed for each of the four telecommunication room scenarios listed above, our office in conjunction with the SD-DCIE team is providing a recommended three-dimensional estimation approach that can be shared with your respective facility leads and design team to verify all telecommunication rooms do not exceed the specified UTP cable segment of 90 meters.

Step 1: Ensure you have an accurate floor plan that depicts the locations of the telecommunication rooms serving the facility.

Step 2: Utilizing AutoCAD or rule, center on the location of the telecommunication room being assessed.

From the center of the room project out lines, 80 meters in length from that point, in the plan north, south, east and west respectively.

Step 3: At the end each of the 80 meters lines created, connect a line 45 degrees from that point out to the next end point creating a diamond.

Step 4: Validate that all areas served by that telecommunication room fall within the parameters of the diamond overlay.

HEFP/10NA5G/29APR20

Step 5: If the area served by that telecommunication room is within the diamond overlay then the distance, as provided by the estimation tool, is adequate for that telecommunication room.

Step 6: If the area served by that telecommunication room is outside the diamond overlay then the distance, as provided by the estimation tool, is inadequate for that telecommunication room and further investigation is required by electronically testing the cable lengths to see if they pass or physical measurement. Any UTP cabling that does not pass testing protocols and is too long will need to have further design considerations to remedy the distance issue.

Notes

Since it is necessary to account for vertical cable distance, installation of slack for bypassing obstructions, cable management, bend radii and other in-situ obstacles 80 meters is utilized instead of the 90 meters acceptable length. This is to provide a realistic estimation of coverage of the representative telecommunication room.

This estimation tool is a recommended approach to validate fixed cable lengths meet the standards.

Designers and installers remain responsible for ensuring actual cable distances do not exceed the limits in the standards.

Below is a diagram of an example demonstrating the use of the estimation tool.