Selecting the Correct Connector

Selecting the Correct Connector

Written by Don Schultz, Networking Consultant & trueCABLE Customer


All Ethernet cable must be terminated at both ends. One way is to use a RJ45 connector. Selecting the correct connector for your Ethernet data cable is entirely dependent upon the type and construction of the cable to be run.


If the cable is shielded, you will want to use shielded RJ45 connectors. Conversely, if the cable is unshielded, you will want to use unshielded RJ45 connectors. Using a shielded connector on an unshielded cable will yield no benefit, although it won't cause issues. The same cannot be said for using an unshielded connector on a shielded cable. Shielded cables need shielded connectors for the ground and shield to function properly.

Shielded vs Unshielded RJ45 Connectors

Next, you need to conduct research on the cable and connectors. You will need to know:

  • Ethernet category rating for the cable and connector (for example, Cat5e/6/6A)
  • OD (outside diameter) of the cable (the overall thickness) and the maximum cable OD the RJ45 connector can accept
  • AWG (American wire gauge) conductor size, and if possible the conductor insulation diameter (the actual conductor wire plus insulation thickness) and the size the connector is compatible with
  • If the cable has solid or stranded conductors, and if the connector will work with that type of conductor

Wire Closeup Info

Let’s take a typical indoor wiring project as an example. In this scenario:


  • The cable run needs to meet Cat6 specifications, and therefore the connector too
  • Shielded cable is not needed, so unshielded connectors are proper

Here is an example of trueCABLE’s information and what you are looking for:

Cat6 Riser Spec Info

Based upon the specifications, we have CAT6 CMR Riser unshielded cable with a 23AWG conductor. The conductor insulation diameter is 0.96mm and the OD is 5.90mm. The conductors are solid. 

Here is an example of a manufacturer’s connector specifications with the most relevant information highlighted:


  • Cat6
  • Eight conductor mod plug with loading bar
  • For conductors with an OD range of .044”
  • 3 prong contact for solid conductors only
  • Max cable jacket OD, 0.280”
  • RoHS & UL Compliant

This manufacturer has expressed their specifications in inches. Converting this we come up with the following:


  • Conductor with insulation OD accepted is up to 1.11mm
  • Maximum cable OD is up to 7.11mm


Looking back at the trueCABLE specification, this connector meets the requirements of the cable.


  • For cable insertion into the back of the connector, connectors come in three primary types:
    • Push-in
    • Push-in with modular load bar
    • Pull-through
  • A higher category rated connector will not necessarily be physically backward compatible with lower rated cable due to cable thickness (OD)
  • Using a higher rated connector than your cable does not provide any additional performance benefit, but there is no harm in doing so
  • You may be forced into using a higher rated connector since these connectors usually allow for greater cable OD and bigger gauge conductors
  • Buy more connectors than you need. It is wise to test terminate (crimp) the connectors onto the cable to make sure you can work with them. In addition, if you make a bad crimp then you can simply use any extras.  Even the most experienced installers make a bad crimp from time to time.
  • If you are new to this kind of activity, then practice as much as practical. The more terminations you make, the better you will get.
  • Different manufacturers refer to measurements differently and in either English or Metric units
  • A manufacturer might indicate their Ethernet cable has 23AWG conductors but provide no information on the conductor insulation diameter. If you cannot locate this information, then select a connector that can accept a wide range of conductor diameters such as 22AWG through 24AWG if you are using 23AWG conductor cable. This is likely a safe choice, but there are no guarantees.
  • If you do make a bad termination, then the connector is trash and cannot be reused
  • Cable strain relief boots are helpful, but entirely optional


trueCABLE presents the information on our website, including the “Cable Academy” blog and live chat support, as a service to our customers and other visitors to our website subject to our website terms and conditions. While the information on this website is about data networking and electrical issues, it is not professional advice and any reliance on such material is at your own risk.

Albert Kleyn February 14, 2020

DON, Yet again an excellent and clearly written article.
Am most grateful for the down to earth and supurbly written explanations.
Albert, Rep. Of Ireland.

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