How to wire Ethernet Cables

  How to wire your own ethernet cables and connectors.

  What You Need:

  Required:

  Ethernet Cable – bulk Category (Cat) 5, 5e, 6, 6a or higher ethernet cable

  Wire Cutters – to cut and strip the ethernet cable if necessary

  For Patch Cables:

  8P8C Modular Connector Plugs (“RJ45”)

  Modular Connector Crimper (“RJ45”)

  For Fixed Wiring:

  8P8C Modular Connector Jacks (“RJ45”)

  110 Punch Down Tool

  Recommended:

  Wire Stripper

  Cable Tester

  About the Cable:

  You can find bulk supplies of ethernet cable at many computer stores or most

  electrical or home centers. You want UTP (Unshielded Twisted Pair)

  ethernet cable of at least Category 5 (Cat 5). Cat 5 is required for basic 10/100 functionality, you will want Cat 5e for

  gigabit (1000BaseT) operation and Cat 6 or higher gives you a measure of future

  proofing. You can also use STP (Shielded Twisted Pair) for extra resistance to external interference but I won’t cover shielded connectors. Bulk ethernet cable comes in many types, there are 2 basic categories,

  solid and braided stranded cable. Stranded ethernet cable tends to work better in

  patch applications for desktop use.

  It is more flexible and resilient than solid ethernet cable and easier to work

  with, but really meant for shorter lengths.

  Solid ethernet cable is meant for longer runs in a fixed position.

  Plenum rated ethernet cable must be used whenever the cable travels through

  an air circulation space. For example, above a false ceiling or below a raised

  floor. It may be difficult or

  impossible to tell from the package or labeling what type of ethernet cable it is, so peal out an

  end and investigate.

  Here is what the internals of the ethernet cable look like:

  Cat 5 cable

  Internal Cable Structure and Color Coding

  Inside the ethernet cable, there are 8 color coded wires. These wires are twisted

  into 4 pairs

  of wires, each pair has a common color theme. One wire in the pair being

  a solid or primarily solid colored wire and the other being

  a primarily white wire with a colored stripe (Sometimes

  ethernet cables won’t have any color on the striped wire, the only

  way to tell which is which is to check which wire it is twisted around). Examples

  of the naming schemes used are: Orange (alternatively Orange/White) for

  the solid colored wire and White/Orange for the striped cable.

  The twists are extremely important. They are there to counteract

  noise and interference. It is important to wire according to a standard

  to get proper performance from the ethernet cable. The TIA/EIA-568-A specifies two wiring

  standards for an 8-position modular connector such as RJ45. The two wiring

  standards, T568A and T568B vary

  only in the arrangement of the colored pairs. Tom writes to say “…sources

  suggest using T568A cabling since T568B is the

  AT&T standard, but the US Government specifies T568A since it matches USOC

  cabling for pairs 1 & 2, which allows it to work for 1/2 line phones…”.

  Your choice might be determined by the need to match existing wiring, jacks or

  personal preference, but you should maintain consistency. I’ve shown both below for straight

  through cabling and just T568B for crossover cabling.

  About Modular Connector Plugs and Jacks:

  The 8P8C modular connectors for Ethernet are often called RJ45 due to their physical resemblance. The plug is an 8-position modular connector that looks like a large

  phone plug. There are a couple variations available.

  The primary variation you need to pay attention to is whether the

  connector is intended for braided or solid wire.

  For braided/stranded wires, the connector has sharp pointed contacts that actually pierce the wire. For solid wires, the connector has fingers which cut through the

  insulation and make contact with the wire by grasping it from both sides.

  The connector is the weak point in an ethernet cable, choosing the wrong

  one will often cause grief later. If you just walk into a computer store, it’s nearly impossible to tell what type of plug it is. You may be able to determine what type it is by crimping one without a cable.

  Modular connector jacks come in a variety styles intended for several different mounting

  options. The choice is one of requirements and preference. Jacks are

  designed to work only with solid ethernet cable. Most jacks come labeled with color

  coded wiring diagrams for either T568A, T568B or both. Make sure you end up with the correct one.

  Here is a wiring diagram and pin out:

  RJ45 jack pin out

  Modular Connector Plug and Jack Pin Out

  Ethernet Cable Pin Outs:

  There are two basic ethernet cable pin outs. A straight

  through ethernet cable, which is used to connect to a hub or switch, and a

  crossover ethernet cable used to operate in a peer-to-peer fashion

  without a hub/switch. Generally all fixed wiring should be run as straight

  through. Some ethernet interfaces can cross

  and un-cross a cable automatically as needed, a handy feature.

  Standard, Straight-Through Wiring Diagram(both ends are the same):

  RJ45 Pin #

  Wire Color

  (T568A)

  Wire Diagram

  (T568A)

  10Base-T Signal

  100Base-TX Signal

  1000Base-T Signal

  1

  White/Green

  white/green

  Transmit+

  BI_DA+

  3

  White/Orange

  white/orange

  Receive+

  BI_DB+

  5

  White/Blue

  white/blue

  Unused

  BI_DC-

  7

  White/Brown

  white/brown

  Unused

  BI_DD+

  Straight-Through Ethernet Cable Pin Out for T568A

  RJ45 Pin #

  Wire Color

  (T568B)

  Wire Diagram

  (T568B)

  10Base-T Signal

  100Base-TX Signal

  1000Base-T Signal

  1

  White/Orange

  white/orange

  Transmit+

  BI_DA+

  3

  White/Green

  white/green

  Receive+

  BI_DB+

  5

  White/Blue

  white/blue

  Unused

  BI_DC-

  7

  White/Brown

  white/brown

  Unused

  BI_DD+

  Straight-Through Ethernet Cable Pin Out for T568B

  Crossover Cable Wiring Diagram:

  RJ45 Pin # (END 1)

  Wire Color

  Diagram End #1

  RJ45 Pin # (END 2)

  Wire Color

  Diagram End #2

  1White/Orangewhite/orange

  1White/Greenwhite/green

  3White/Greenwhite/green

  3White/Orangewhite/orange

  5White/Bluewhite/blue

  5Brownbrown

  7White/Brownwhite/brown

  7Blueblue

  Crossover Ethernet Cable Pin Outs

  +Note: The crossover ethernet cable layout is suitable for 1000Base-T

  operation, all 4 pairs are crossed.

  How to wire Ethernet Patch Cables:

  Strip off about 2 inches of the ethernet cable sheath.

  Untwist the pairs – don’t untwist them

  beyond what you have exposed, the more untwisted cable you have the worse

  the problems you can run into.

  Align the colored wires according to the wiring diagrams above.

  Trim all the wires to the same length, about 1/2″ to 3/4″

  left exposed from the sheath.

  Insert the wires into the RJ45 plug – make sure each wire

  is fully inserted to the front of the RJ45 plug and in the correct order.

  The sheath of the ethernet cable should extend into the plug by about 1/2″ and

  will be held in place by the crimp.

  Crimp the RJ45 plug with the crimper tool.

  Verify the wires ended up the right order and that the wires extend

  to the front of the RJ45 plug and make good contact with the metal

  contacts in the RJ45 plug

  Cut the ethernet cable to length – make sure

  it is more than long enough for your needs.

  Repeat the above steps for the second RJ45 plug.

  How to wire fixed Ethernet Cables:

  Run the full length of ethernet cable in place, from endpoint to endpoint, making sure to

  leave excess.

  At one end, cut the wire to length leaving enough length to work, but not too much

  excess.

  Strip off about 2 inches of the ethernet cable sheath.

  Align each of the colored wires according to the layout of the jack.

  Use the punch down tool to insert each wire into the jack.

  Repeat the above steps for the second RJ45 jack.

  If an ethernet cable tester is available, use it to verify the proper connectivity of the cable.

  That should be it, if your ethernet cable doesn’t turn out, look closely

  at each end and see if you can find the problem. Often a

  wire ended up in the wrong place or one of the wires is making no contact or

  poor contact. Also double check the color coding to verify it is correct. If you see a mistake or problem, cut the end off and start again. A ethernet cable tester is invaluable at identifying and highlighting these issues.

  When sizing ethernet cables remember that an end to end

  connection should not extend more than 100m (~328ft).

  Try to minimize the ethernet cable length, the

  longer the cable becomes, the more it may affect performance. This is usually

  noticeable as a gradual decrease in speed and increase in latency.

  Notes:

  Power over Ethernet (PoE):

  Power over Ethernet has been implemented in many variations before IEEE standardized 802.3af. IEEE 802.3af specifies the

  ability to supply an endpoint device with 48V DC at up 350mA or approximately 16.8W. IEEE 802.3at updates the PoE standard to supply up to 600mA or approximately 28.8W, it is often known as PoE+. The power is delivered using two pairs in the ethernet cable. The device must be capable of receiving power on either

  the data pairs [Mode A] (often called phantom power) or the unused pairs in 100Base-TX [Mode B]. IEEE 802.3bt further updates the PoE standard to use all four pairs of the cable to deliver up to 90W of power. PoE can be used with any ethernet

  configuration, including 10Base-T, 100Base-TX or 1000Base-T. Power is only supplied when a valid PoE endpoint is

  detected by using a low voltage probe to look for the PoE signature on the endpoint. PoE power is typically supplied

  in one of two ways, either the host ethernet switch provides the power, or a “midspan” device is plugged in between

  the switch and endpoints and supplies the power. No special cabling is

  required.

  RJ45 Pin #

  Wire Color

  (T568A)

  Wire Diagram

  (T568A)

  10Base-T Signal

  100Base-TX Signal

  PoE

  1

  White/Green

  white/green

  Transmit+

  Mode A +

  3

  White/Orange

  white/orange

  Receive+

  Mode A –

  5

  White/Blue

  white/blue

  Unused

  Mode B +

  7

  White/Brown

  white/brown

  Unused

  Mode B –

  Power over Ethernet Power Delivery

  Protocol Details:

  ProtocolStandardSymbol

  EncodingSymbol Rate (Mbaud)Data EncodingData Bits per SymbolPairs per ChannelPairs UsedNyquist Frequency Bandwidth (MHz)Minimum Cable Category

  10Base-TIEEE 802.3iManchester10None112103

  1000Base-TIEEE 802.3ab4D-PAM5125None24462.55e (5)1

  5GBase-TIEEE 802.3bzDSQ128 (2D-PAM16)400LDPC(1723,2048), 64B/65B, CRC83.125442006 (5e)2

  25GBase-TIEEE 802.3bqDSQ128 (2D-PAM16)2000LDPC(1723,2048), 64B/65B, CRC83.12544100084

  Data Rate=Symbol Rate x Data Bits per Symbol x Pairs per Channel

  The combination of the Symbol Encoding and Data Encoding determines how

  many Data Bits per Symbol there are.

  1. Designed to work on most Cat 5 ethernet cable, Cat 5e specifications

  ensure 1000Base-T operation.

  2. Although designed for Cat 5e/6, not all cabling will be usable at the full range, especially for 5GBase-T on Cat 5e.

  3. Reduced range when used with Cat 6 (55m), Cat 6a supports the full 100m range. Some Cat 5e may support operation at reduced distance.

  4. 30m range.

  Cable Category Details:

  Cable CategoryRated Nyquist Frequency

  Bandwidth (MHz)Common Uses

  1NoneTelephone Wiring

  316Telephone Wiring, 10Base-T

  5100100Base-TX, 10Base-T

  62501000Base-T, 100Base-TX

  71600>10GBase-T

  8200025GBase-T, 40GBase-T

  Increasing category levels are backward compatible.

  Manufacturers will often test and certify their ethernet cable well beyond the

  standards.

  1. Category 7/7a specification wiring does not use RJ45 connectors.

  Related Reading Material

  Get IEEE 802 – Ethernet Standards

  Charles Spurgeon’s Ethernet Website

  Network Connection Speeds Reference

  Fiber Optic Connector Reference

  Ethernet:

  The Definitive Guide

  The

  All-New Switch Book: The Complete Guide to LAN Switching

  Technology times, since inception on September 1, 1997

  Last Changed: January 31, 2019

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