Re: Cat-5e

Leonard Davis

Thank you Mark, I have NCE Power Cab and SB5. So I take it from what you have said the CAT 5 UTP's really only allow you to wire up the layout easier. So there is no other advantage to the using the CAT 5  other than ease of installation.

L. D.

---In wiringfordcc@..., <gurriesm@...> wrote:

To answer your specific questions, the Cat Cables  and the RJ12 cables are NOT alike at all.  Both the wiring and the plugs are not compatible with each other. 

What DCC system are you using?  The DCC system will determine the type of cables you need to expand the cab/throttle bus of the DCC system.

CAT or any ethernet (CAT5, CAT5e & CAT6) cable uses a ROUND 8 conductor cable with a larger 8 conductor telco plug.  They are wired Pin1 to Pin1.  The only DCC system that uses this type of cable is MRC.  MRC also allows use of RJ45 cables too.  See notes below.

RJ11 is a flat 4 conductor cable that use 4 conductors of a 6 conductor telco plug.  The cable can be wired both in pin1 to pin 1form  or flipped as in Pin 1 to Pin6.   The only DCC system that uses this cable is EasyDCC.

RJ12 is a flat 6 conductor conductor cable that use a 6 conductor telco plug.  A TRUE RJ12 cable is only wired Pin1 to Pin1.    This cable is used by NCE and Digitrax.


1) RJ11 is your common everyday telephone cable you can fine at any store that carries telephone supplies.  RJ11 is a telephone code name/term for this type of cabling.   Technically RJ11 is supposed to be wired Pin1 one to Pin1 per the RJ specifications.   But the specification allows for a flipped cable (Pin1 to Pin6) in they way it is designed.

2)  RJ12 is NOT a telephone company term.  It evolved as an data industry term to show that it is wired differently than a RJ11 cable.   Be aware than many time RJ12 cable are mis-identified as RJ11 cables.    That comes about only because you can use a RJ12 in a RJ11 setup and it will work but the reverse is not true.  At first glance at RJ12 may look to be the same as the RJ11 but upon closer inspection you will see the cable is wider/fatter because of the extra two wires. The RJ12 is sometimes called a RJ11 Data Cable since it is used in low speed data systems unlike Ethernet.  

3) RJ11-6.   You can get RJ12 Cables incorrectly wired in Pin1 to Pin6 format if your not careful.  They may be called RJ11-6 cables.  Technically such cables will never work with NCE and also run the risk of damaging NCE throttles but in practice it does not happen.  These cables will work with Digitrax but can cause other side effect problems such a flipped booster phasing or in some cases will not allow some digitrax devices to work correctly such as the BDL-16 and BDL-168.  A RJ11-6 cable will work in a RJ11 telephone setup just like the RJ12 will work.

4) RJ45 cable is not a CAT cable but uses the same 8 conductor telco connector.  RJ45 cables use a very wide 8 conductor flat cable that looks like a oversize telephone cable.  RJ45 is a technical term used by the telephone company.  This form of a cable will also work on MRC setups.  The term RJ45 cable is often incorrectly associated with CAT cables for the similar reasons R12 and RJ11 cables are mixed up.

5) NCE is now offering a new line of cab bus products that use the CAT cables for the layout side of the cab bus wiring.   NCE is attempting to allow on to use the cheaper and more common standard CAT cables to make the cab bus wiring easier.   RJ12 cables are harder to find and one needs to worry about the proper Pin1 to Pin1 wiring of a RJ12 cable when purchasing them.   The older RJ12 versions are still supported.

6) RJ means Registered Jack which is a telephone industry term.  It describes a level of wired telephone service as in how many telephone lines (hence number of wires) the connection it will support.   It does not actually state the connectors to be used.   The common connectors we associated with RJ11, Rj12 and RJ45 cables are actually part of larger modular connector system that included the flat cable.  This connection system allowed fast, easy and inexpensive cable construction.  These "modern" connection system came long after the RJ definitions were set.

On Sep 30, 2013, at 9:00 PM, <lleeblues@...> <lleeblues@...> wrote:

For some reason I can not find any file on the difference between RJ-12 cable and CAT-5e cable for cab buss. I know this subject5 has been covered before.

 I would appreciate any info available. I don't know if I need CAT-5e or stay with RJ-12.
Thanks in advance.

Leonard Lee Davis

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics:

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