How To: Terminating a Field Term Plug Onto Cat6A Direct Burial Unshielded Ethernet

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

When terminating Cat6A Ethernet cable of any kind, including Cat6A direct burial unshielded Ethernet cable, it is good to have options that will give you the performance you expect, especially if your individual installation needs to deviate a bit from what is considered “normal practice”. What and who defines “normal practice”? The ANSI/TIA 568 standard does, and for good reason. Normal practice is to terminate solid copper structure Ethernet cable at both ends to keystone jacks or patch panels as explained in the second part of this series, How To: Terminating a Keystone Jack Onto Cat6A Direct Burial Unshielded Ethernet. You get the key advantage of Insulation Displacement Contact (IDC) style terminations with this practice. The IDC to IDC method would be considered the “permanent link” of your system that you patch into. You would then complete the “channel” with two factory pre-terminated stranded copper patch cords at both ends. 

However, not all installations are the same and sometimes the traditional permanent link with patch cord strategy is not practical. There could be structural reasons why this cannot be pulled off, or you might be near the maximum distance of Ethernet and adding patch cords on both sides puts you over the magic “328 foot” number. So is there another equally effective way to terminate your solid copper Cat6A direct burial Ethernet cable to get the performance and reliability you seek? Yes there is, and it involves Category rated field termination plugs. Field termination plugs are considered high quality IDC terminations and can be used to create the entire channel, skipping the stranded copper patch cords.

Cat6A Unshielded Field Termination Plug. Notice the IDC termination prongs.

In this third part of the series, we will discuss the ins and outs of field termination plugs, how to terminate them onto Cat6A Unshielded Direct Burial Ethernet cable, and some installation considerations! Please watch this video below and then come back and finish reading the blog for very detailed pictures and additional information!

What exactly are we creating? Isn’t this a patch cable?

When you terminate both ends of solid copper Ethernet cable to male connectors then this is considered to be a patch cable, and sometimes is referred to as a “direct attach cable”. It all depends on how you are using the cable. Patch cords are normally for patching into an existing permanent link. On both ends of the permanent link you have female ports to accept the patch cords. Normally you would buy the correct length patch cable already pre-terminated with 8P8C (aka RJ45) connectors and simply plug and go. However, sometimes you need to custom create such a cord and in other cases your cable needs to be hundreds of feet long, perhaps directly buried outside. Factory made patch cords won’t cut it.

But why field termination plugs? Why not RJ45s?

It is a bad idea to hand terminate 8P8C modular plugs onto both ends of solid copper Ethernet cable and expect high speeds with any degree of reliability. For much more on why 8P8C RJ45s can be the source of headaches, please see Terminating Pass-Through RJ45 Connectors onto Solid Copper Ethernet Cable  --  A Really Bad Idea?

PCB inside of the trueCABLE Cat6A Unshielded Field Termination Plug.

Field termination plugs have a Printed Circuit Board (PCB) inside just like keystone jacks do. That PCB is Category rated and also impedance matches your link. You get a lot of “secret sauce” helping you out. 8P8C (aka RJ45) modular plugs have none of the secret sauce and all of the problems you might encounter when terminating Ethernet cable! Field termination plugs are not nearly as “fitment sensitive” as 8P8C modular plugs and play much more nicely with solid copper Ethernet due to the way the IDC prongs bite into the conductor wires from 90° angles. 

So, if you intend to custom create a patch cord that can really go the distance and must be reliable, field termination plugs are the only way to go assuming their physical size does not limit you…

Understanding the benefits and trade-offs of field termination plugs

As with anything in life there will be advantages and disadvantages. Utilizing this alternative method of termination should be kept to a minimum and as needed. You need to carefully consider your individual installation and opt for the traditional method where possible and make use of alternative strategies when necessary.

Benefits of links using field termination plugs:

• You are using solid copper conductors for the whole link, which gives the best possible performance and PoE handling over distance
• You might get additional length depending on the ambient temperature conditions--up to 335 feet if you can keep the cable at 68℉ or less
• Stranded copper patch cords are absent from the mix; so you don’t need to de-rate (shorten) your channel length for that. You need only derate for temperature.
• Field termination plugs are human friendly and easy to terminate for novices

Trade-offs of links using field termination plugs:

• This is solid copper Ethernet cable we are talking about, so it does not like repeated handling. Stranded copper patch cord is meant for repeated handling.
• You lose flexibility for adds, changes, and corrections that you would otherwise have gained with a more traditional “rack to jack” strategy making use of patch panels, keystone jacks, and factory pre-made patch cords
• Field termination plugs are considerably larger than 8P8C (aka RJ45) modular plugs due to the need for a printed circuit board (PCB) inside along with a human-friendly toolless termination method. Field termination plugs are also more expensive than plain plastic 8P8C modular plugs.

Field termination plugs are physically larger than 8P8C modular plugs.

Ideal Use Case

Why would you wish to use this strategy for select links in your Local Area Network cable system? The simple answer is backhauls (backbones). The idea is you need a highly reliable and typically super high speed connection from one powered device to another. This normally takes the form of two Ethernet switches that need to be connected together to expand a network where speed and reliability are paramount, and a fiber optic connection is not an option or impractical. If you are curious as to how backbones are used in formal structured cable systems, please see What's the Difference Between Backbone and Horizontal Cabling?

When installing high speed Ethernet cable designed to interconnect two structures, sometimes you are limited in how you get that done due to structural limitations or lack the expertise to install a more formal structured cabling system.  At the same time, you wish to leverage Cat6A unshielded direct burial cable to get the job done because you need or want 10Gbps speeds (or at least the possibility of achieving that down the line) . For example, assume you need to connect a primary home to a repurposed garage. You measured, and you know you will need a cable that is 290 feet long and must be buried. You need a “bullet proof” alternative to the regular way. You are in luck. First, though, you should probably read up on the best way to go about how to actually bury direct burial Ethernet cable correctly, so take a look at Into the Great Outdoors: Running Ethernet Cable Outside.

Second, you don’t need to be concerned about ambient temperatures above 68℉ because the cable will be buried at least 10” deep, so we will proceed with the permissible full length of 335 feet for this scenario. The run is less than that at 290 feet, so this is still in specification.

How did I come up with the 335 foot number? Isn’t it supposed to be 295 or 328 feet? Well, those other maximum lengths apply in other circumstances, and this is the one and only exception! Here is the proof:

Total channel length with patch cord de-ratings. Notice column "D = 1.0", 102(335).

D = 1.0 denotes a solid copper Ethernet “patch cord”. Maximum length is 335 feet when there is no “permanent link” in the middle. In other words, this exactly fits the situation at hand. If you are curious about this chart and what it all means, please see Calculating Ethernet Cable Overall Channel Length for Success.

Cat6A unshielded field termination plugs & Cat6A unshielded direct burial cable to the rescue!

Tools and Materials

• Cat6A Unshielded Direct Burial Ethernet cable, bulk solid copper
• 2 x Cat6A Field Term Plugs, Unshielded
• Cable cut and strip tool
• Micro flush cutters
• Field term plug closure tool (parallel pliers that are optional but strongly recommended--otherwise slip-joint pliers can be substituted)

Once you install your cable, you will need to perform the following steps at both ends.

Cable Stripping Guide

These are the tools you will need for cable preparation.

Strip off about 1.5 to 2” cable jacket. The goal is to SCORE the jacket, not cut through!

Once the jacket has been scored, break the jacket at the score.

Jacket removed revealing the PE tape, rip cord, and waterblock tape. All need to be removed with the flush cutters right down to the jacket edge.

Removal process with flush cutters. Be careful not to nick any conductors during this process or you will need to start over!

Once the dielectric wraps have been removed, splay the conductor pairs into a star pattern exposing the center spline.

Carefully remove the spline. Make four downward cuts, one cut on each “wing”. Resist the temptation to cut the spline straight across as this will make termination more challenging.

Once the spline has had four cuts, twist to remove the excess spline.

Termination Guide

Now that the cable has been prepared for termination, it is time to put on the hardware! Here we go!

Lacing up the conductor holder cap. We used the T568B pattern for this. Be sure to place the cable jacket edge right to the green line as this pre-sets the 0.50” untwist maximum.

A helpful tip. Untwist the conductor pairs that will seat into the rear slots fully, and seat them first. This will effectively set the 0.50” termination distance AND help you keep the cap steady when seating the forward pairs.

You may use either the T568A or T568B pattern. One is NOT better than the other. The key is to pick a color sequence scheme and stick with it!