by Barry Poitras
Knowing the type of cabling infrastructure being implemented on your next project is very important. It can be critical to the success of the coordination between other disciplines and cost impacts for the overall budget of the project. The type and quantity of cabling infrastructure can impact the project by creating inadequate pathways that have to be revised during or worse after installation having a huge impact on the schedule and budget of the project. A solid understanding of questions to ask during the early stages of the design project can aid in success of the project.
For many years now, the telecommunications industry has created and used the classification of Unshielded Twisted Pair (UTP) copper cable in terms of “Categories”. The term Category was developed by standards organizations EIA/TIA to assist in design and implementation of structured cabling systems that meet or exceed the transmission characteristics of the ever increasing speed and bandwidth compression of Ethernet switch manufacturers to send high speed signals over unshielded copper cables.
As cable manufacturers continued to develop and push their cables beyond the testing parameters of the standards organizations of ANSI/EIA/TIA, the manufacturers began to promote their newest version of the category 6 cable as better than the competition due to the boundaries or “headroom” in which they tested their cable above and beyond the standards requirement. This forced the standards organizations into reviewing, testing, validating and accepting the new levels of performance of the higher levels from cable manufacturers. However, instead of classifying the next level of cable as Category 7, 8, etc. the standards organizations labeled them as levels within the category 6 standard. This has created great confusion for end users, design Specifiers and integrators trying to review competitive proposals.
There are currently four levels of category 6 cable. They are category 6 minimum compliance, category 6 mid compliance, category 6 maximum compliance, category 6a augmented. As you can see this has created a source of frustration for design engineers and contractors both on specifying and RFP responses since signal quality, cost and size of each cable can have an impact on the project. Let’s review each of these and discuss the potential impact on the next project.
As a general rule of thumb, signal quality goes up as category level goes up, but so does the cost of the cable. The reason is that more bits per second can be sent over the same length of the cable. For instance jumping from 1 gigabit per second Gb/s to 10 Gb/s will be limited to approximately 100 feet on the mid compliant as opposed to 300 feet on the augmented level. This can have an impact on the client’s IT staff that may be rolling out Ethernet switches and network interface cards with higher transmission rates than the cabling cannot support. This will only manifest itself in transmission failures after the cabling infrastructure is in installed.
The cost of each level also varies and can have a huge impact on the project budget and bidder responses. The delta between Category 6 maximum compliance to Category 6 minimum compliance cable is approximately $100 per 1000 feet of cable. In addition to cost, Category 6A cable has almost a three times larger cable outside diameter size than category 6 which can have a huge impact on conduit pathways and boxes usually specified under the electrical design.
In conclusion, it is best to know exactly what type of cabling infrastructure is being specified, proposed and installed to ensure a smooth coordination and expectation of the structured cabling system solution.
Barry Poitras, RCDD, is a principal and the director of telecommunications and ESS design at RDK Engineers in Andover, Massachusetts.