Terminating Cat6A Shielded Direct Burial Ethernet for Performance

Written by Don Schultz, trueCABLE Senior Technical Advisor, Fluke Networks Copper/Fiber CCTT, BICSI INST1, INSTC, INSTF Certified

4K HDBASE-T and 10G Internet over coaxial is here, and you should be ready for it! Up until now, our Cat6 Shielded Direct Burial Ethernet cable was good enough to handle direct burial or general outdoor situations equally well. Well, that Cat6 cable was good as long as you did not require 10GBASE-T past 165 feet or required shielded cable that could sustain 10G at 328 feet when outside. Many installers are finding themselves in a situation where they need:

• Tough direct burial cable that can be used above or below ground
• Shielded to handle issues with ESD (Electrostatic Discharge) or EMI/RFI (Electromagnetic and Radio Frequency Interference)
• Cabling that reaches 328 feet without signal loss when running 10GBASE-T (10Gb/s)

Today we are going to cover detailed best practices and termination procedures for the latest addition to the trueCABLE lineup, our Cat6A Direct Burial Shielded Ethernet LAN cable. Now, networks that need to drive 10GBASE-T and provide the best possible cable for 4K (HDBASE-T) have a shielded direct burial cable that will completely future proof your network. This blog specifically addresses how to get the most when installing and terminating this brute of a cable. And, a brute it is.

If the process of direct burial intimidates you, then you are not alone. We make this process more accessible in Into the Great Outdoors: Running Ethernet Cable Outside.

Cable Characteristics:

• ANSI/TIA 568-2.D compliant and Permanent Link tested to Cat6A performance
• Shielded
• CMX rated LLDPE outdoor jacket for rain, snow, UV sunlight, and ice resistance
• Water blocking tape for direct burial applications
• Ability to be used above or below ground
• 23AWG solid pure copper conductors
• Supports PoE, PoE+, and PoE++ (IEEE 802.3af/at/bt) up to 90W DC
• Rated for 300V
• Thick 7.60mm cable jacket outer diameter (OD)
• 1.14 mm insulated conductors
• Bend radius is 2.00 inches (best visualized as bend diameter, which means if you turn the cable into a circle it cannot be tighter than 4.00 inches across)

 The full spec sheet can be found here.

Installation Best Practices

That last thing you want to do is impair the performance of your high performance cable. There are a number of ways to cause yourself issues, but if you follow some basic guidelines you will achieve success.

• Do not exceed 328 feet. Total end to end link length is called the Channel and may encompass one or more patch cables and your solid copper permanent cable installation. Formal guidance is solid copper Ethernet cable should not exceed 295 feet, and this leaves 33 feet in total (at both ends) for patch cable.
• Do not exceed the bend radius for the cable. This particular cable requires a bend no tighter than 2 inches, and can be easily visualized if you turn the cable into a circle. The circle should be no tighter than 4 inches, If you bend the cable any tighter damage may occur and reduced performance will result.
• Use shielded Cat6A patch factory pre-made patch cords. Don’t attempt to make patch cords in the field unless there are no alternatives. Factory made patch cable has been assembled by a machine with precision and tested.
• Know your worst case ambient temperature! The run distances of 328 feet or 295 feet are at 68℉. As your temperatures go up, the permitted run lengths go down. Consider your installation environment. Will your cable be buried most of the length? If so, you can use the maximum distances for 68℉. If your cable will be above ground and subject to higher summer temperatures, find out the highest temperature in your area for the last five years and base all run length maximums on that worst case upper temperature. Low temperatures do not affect performance unless you are in the arctic. A handy guide for run lengths based upon temperature can be found in Temperature's Effect on Ethernet Cable Length. A quick rule of thumb is if your solid copper Cat6A cable run that is exposed to the outdoors will not exceed 250 feet, you don’t have to worry about it.

Termination Best Practices

• Use the most effective termination hardware. The best terminations are IDC terminations (insulation displacement contact) and this is the termination strategy that keystone jacks, 110 patch panels, and field termination plugs use. RJ45 8P8C plugs should be left to factory pre-terminated patch cords, except in some rare circumstances that we will cover later.**
• Use shielded Cat6A termination hardware. Keystone jacks, 110 patch panel if you are using one, and field termination plugs should be shielded Cat6A. If you substitute in a lower Category for any of these items, your runs will likely perform to the lower Category.
• Shielded cable must be bonded to ground. Shielded cable should be bonded to ground for the cable shield to function properly, or even to avoid issues induced by a “floating” cable shield. Bonding and grounding is beyond the scope of this blog, but it is addressed in our Commercial Bonding and Grounding of Ethernet Cable Systems blog. 
  Pay close attention to untwist. The maximum distance of the last twist in any one pair to the actual point of electrical contact is 1/2 inches. Tighter is better. Ideally, the last twist in the pair will be right up to the point of termination, but this is not always possible. When it is not physically possible to get the last twist right up to the point of termination, then one additional untwist is OK but no more. Adding a half-twist in an attempt to compensate may disrupt the electromagnetic balance of the cable and actually decrease performance.

** A common installation scenario is a MPTL or Modular Plug Terminated Link. Fancy term, but essentially this means a patch panel or keystone jack on one end and a male plug on the other end for purposes of PoE (Power over Ethernet). This is used for applications such as WiFi access points and surveillance cameras. Ideally, the male plug will be a field termination plug but due to size constraints this may not be possible. In cases such as this, it is permissible to put a RJ45 8P8C on your solid copper Ethernet cable, but only at one end. That plug must be properly fit!

Modular Plug Terminated Link

Here are some pictures of the types of terminations you will want to use to achieve the best performance from your Cat6A shielded direct burial cable, all validated and tested to fit perfectly onto your cable and sold by trueCABLE:

Performance and Compatibility Test Proof

As is normal for trueCABLE, we test our Ethernet cable and accessories together as a system. This is an example Fluke DSX-8000 test result of our Cat6A Shielded Direct Burial Cable (in black) using a Cat6/6A Pass Through RJ45 Connectors｜Shielded at one end (this is a pass-through 8P8C plug) and a tool-less shielded Cat6A keystone jack at the other end. This is known as a MPTL or “Modular Plug Terminated Link” which is commonly used for PoE device connections. This is a stringent test and demonstrates that our connection hardware has been fit and tested with the cable.

 Various Bond Strategies

Earlier we spoke about “bonding to ground”. Although we won’t discuss the concept of bonding and grounding at length I will demonstrate several valid strategies of bonding the Ethernet cable shield to your termination hardware. Of all of them, I prefer the copper fabric strips method.

Method 1. This is an oldie, but goodie. Foil shield folded backwards and ESD drain wire wrapped around the foil.

Method 2. Foil shield removed and ESD wire wrapped around jacket. Valid, but a little difficult to deal with due to the ESD drain wire shifting around easily and this can lead to a cable shield that is not bonded properly.

Method 3. This is identical to method 2, but now the bonding surface is much broader via the use of a conductive adhesive copper fabric strip. I prefer this method.

So, that is the recommended way of working with and terminating our Cat6A Shielded Direct Burial Ethernet. There is a bit more to it than Cat6A F/UTP Riser, for example, but all the extra stuff inside and tough exterior LLDPE CMX jacket give it the ability to perform at 10G right in the dirt!

HAPPY NETWORKING!

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