How Do I Wire a Network Cable? Step-by-Step RJ45 and Keystone Jack Guide (T568B)
A dead network jack or a patch cable that is a few feet too short is a common frustration in any office. If you have asked yourself “how do I wire a network cable,” the good news is that the core skill is learnable in an afternoon. You need the right tools, the right wiring order, and a careful hand.
This guide covers the two terminations most people need: crimping an RJ45 plug onto a patch cable and punching down a keystone jack on in-wall cable. It also explains the T568A and T568B color codes, how to test your work, and when a project is better handed to a licensed cabling contractor. Businesses looking for reliable network cabling services in Carson, CA can get professional assistance with cable selection, installation, wiring, and network setup.
Table of contents
- Before you start: plug or jack?
- Tools and materials
- The wiring order: T568B and T568A
- How to wire an RJ45 plug (patch cable)
- How to wire a keystone jack (in-wall cable)
- Wiring a patch panel
- How to test a network cable
- Troubleshooting common problems
- Common mistakes and misconceptions
- When to call a professional
- Key takeaways
- FAQ
Before You Start: Plug or Jack?
The first question is not how to wire the cable, but which end you are building. There are two main types of termination, and they use different cable and different tools.
- RJ45 plug (crimped): The clear connector on a patch cable. It uses stranded cable and a crimp tool.
- Keystone jack or patch panel (punched down): The wall outlet or rack port for permanent in-wall cable. It uses solid cable and a punch-down tool.
This matters because solid and stranded cable behave differently. One installation guide explains that fixed in-wall solid cable should terminate to keystone jacks at the room end and a patch panel at the closet or network equipment end, with factory-made patch cables (stranded) for the flexible connection between the wall jack and the device. It also warns that putting a field-crimped RJ45 plug directly on solid cable works initially but the solid conductors are brittle — they crack internally with repeated plug insertion and become intermittent.
There is one recognized exception for devices like ceiling cameras and access points. The TIA approved a cabling topology known as the Modular Plug Terminated Link, or MPTL, which has the horizontal cable terminated using a modular plug rather than an equipment outlet. MPTL links use plugs rated for solid cable and require certification testing. We cover it later in this guide.
Tools and Materials
For crimping an RJ45 plug:
- Stranded Cat6 or Cat6A patch cable (pure copper)
- RJ45 plugs rated for your cable category and conductor type
- Strain relief boots (optional)
- RJ45 crimp tool
- Cable jacket stripper
- Flush cutters
For terminating a keystone jack:
- Solid Cat6 or Cat6A cable (pure copper)
- Keystone jack rated for your cable category
- 110-style punch-down tool with a cutting blade
- Cable jacket stripper
- Wall plate or surface mount box
For testing:
- A continuity or wire map tester at minimum
- A certification tester for commercial or high-speed links
Match every component to the cable. A Cat6A plug on Cat6A cable, a Cat6 jack on Cat6 cable. Mixing categories lowers performance to the weakest part.
Buying tip: Avoid copper-clad aluminum (CCA) cable. It is not compliant with TIA category standards and performs poorly with Power over Ethernet. See our guide to [the most common type of network cable](INTERNAL LINK) for more.
The Wiring Order: T568B and T568A
Every Ethernet cable has eight wires in four color-coded pairs: orange, green, blue, and brown. The TIA-568 standard defines two ways to arrange them, called T568A and T568B. Before wiring a network connection, it is helpful to understand the four types of cables and how their construction and intended applications differ.
T568B (most common in U.S. commercial work)
For T568B, the order from pin 1 is white/orange, orange, white/green, blue, white/blue, green, white/brown, brown.
| Pin | T568B | T568A |
|---|---|---|
| 1 | White/Orange | White/Green |
| 2 | Orange | Green |
| 3 | White/Green | White/Orange |
| 4 | Blue | Blue |
| 5 | White/Blue | White/Blue |
| 6 | Green | Orange |
| 7 | White/Brown | White/Brown |
| 8 | Brown | Brown |
T568A
T568A from pin 1 to pin 8 is white/green, green, white/orange, blue, white/blue, orange, white/brown, brown. The only change is that the orange and green pairs trade places.
Which one should you use?
Both perform the same. Both standards deliver identical electrical performance. The deciding factor is what the building already uses. For US commercial networks, T568B is the usual default. Choose T568A for residential work or when a government or federal specification calls for it.
The one hard rule is consistency. What you must never do is terminate one end of a cable with T568A and the other with T568B — that turns it into a crossover cable, which will not work as a standard straight-through Ethernet connection.
How to find pin 1
Hold an RJ45 plug with the clip facing away from you and the contacts facing up: pin 1 is on the left. A simple memory trick helps too. One guide suggests remembering the pairs in order: Orange, Green, Blue, Brown. For each pair, the striped wire (white/color) comes before the solid color. Exception: Green pair is split around Blue!
Why all eight wires matter
Do not skip any wires. Gigabit Ethernet uses all eight wires, because 1000BASE-T sends data over all four pairs. PoE devices and multigigabit links depend on all four pairs too.
How to Wire an RJ45 Plug (Patch Cable)
Follow these steps to crimp a straight-through patch cable using T568B.
Step 1: Cut the cable to length
Cut the cable squarely with flush cutters. Add a little extra length so you can re-terminate if the first attempt fails. Slide a strain relief boot onto the cable now if you are using one.
Step 2: Strip the outer jacket
Use a cable stripper to remove about an inch of the outer jacket. Rotate the stripper gently so it scores the jacket without nicking the wire insulation underneath. Remove any plastic spline or separator inside Cat6 cable by trimming it flush with the jacket.
Step 3: Untwist and arrange the wires
Untwist the pairs only as much as needed. Straighten each wire and line them up in the T568B order, from left to right: white/orange, orange, white/green, blue, white/blue, green, white/brown, brown. Keep them flat and side by side.
Step 4: Trim the wires evenly
Hold the wires tightly in order and trim them straight across. Leave just enough length to reach the end of the plug while the cable jacket still sits inside the plug body. The goal is short, even wires and very little untwisted length.
Step 5: Insert the wires into the plug
With the plug’s contacts facing up, push the wires straight into the plug. Each wire must slide fully into its channel and reach the metal contact at the front of the plug. The outer jacket should extend inside the plug so the strain relief grips it during crimping. Look through the front of the plug to confirm every copper end touches the end of its channel and that the colors are still in order.
Step 6: Crimp the plug
Place the loaded plug into the crimp tool and squeeze firmly until you feel and hear the contacts seat. This pushes the 8 metal pins through the insulation of each conductor and locks the jacket in the strain relief. Slide the boot over the plug if you used one.
Step 7: Repeat on the other end
Terminate the other end using exactly the same T568B order. Then test the cable before using it.
Tip: For short patch cords, factory-made cables are often more reliable and certified to category performance. Field crimping is best for custom lengths or repairs.
How to Wire a Keystone Jack (In-Wall Cable)
Keystone jacks terminate the solid cable that runs inside walls and ceilings. Instead of crimping, you punch each wire into a metal slot that cuts through the insulation. When setting up a LAN, understanding the cable used in a local area network can help determine the appropriate option for the network installation.
A punch-down tool presses insulated copper conductors into IDC (Insulation Displacement Contact) slots. The IDC blades in the jack slice through the wire insulation and make contact with the copper core. That means you do not strip individual wires, only the outer jacket.
Step 1: Leave a service loop and cut the cable
Pull the cable through the wall opening with some extra length. A small service loop gives room for future repairs. Cut the cable squarely.
Step 2: Strip the outer jacket
Remove about an inch of jacket. One termination guide recommends removing about 25–30mm (1 inch) of outer jacket — enough to reach the contacts without excessive untwisting.
Step 3: Check the jack’s color label
Most keystone jacks print both color codes on the side. Most keystone jacks have a color-coded diagram on the body showing T568A and T568B positions. Use the same scheme as the patch panel at the other end of the run.
Step 4: Lay the wires into the slots
Keep each pair twisted as close to the jack as possible. Separate the pair only at the point where the two wires go into their slots. Lay each wire into the correct slot according to the label, pressing it lightly into the groove.
This is where performance is won or lost. The TIA-568 standard specifies a maximum of 13 mm (0.5 inch) of untwisted conductor at the termination point. For Cat6 at 250 MHz, aim for 10 mm (0.4 inch) or less.
Step 5: Punch down each wire
Place the punch-down tool squarely over each wire with the cutting side facing outward. Push firmly until the tool clicks. This seats the wire and trims off the excess in one motion.
Step 6: Inspect and close the jack
Check that every wire is fully seated at the same depth and that no copper is exposed. Trim any leftover ends. Snap on the jack’s cap if it has one, then mount the jack into the wall plate.
Key point: One guide notes that a bad Cat6 keystone jack termination is the single most common cause of network certification failures, often because one conductor sits a millimeter short of full depth.
Wiring a Patch Panel
The other end of an in-wall run usually terminates at a patch panel in the telecom closet. The process is almost identical to a keystone jack:
- Route the cable neatly to the back of the panel and support it with cable management.
- Strip the jacket and keep the pairs twisted up to the termination point.
- Follow the color label on the panel, using the same scheme as the wall jack.
- Punch down each wire with a 110 tool.
- Label the port and the wall jack with the same identifier.
Individual jacks and panels share tooling with larger termination blocks. Individual Category 5e and better-rated 8P8C jacks (keystone and patch panel) with IDC connectors commonly use the same punchdown ‘teeth’ dimensions and tools as a full size 110 block.
MPTL: Wiring a Plug Directly to a Device
Security cameras, Wi-Fi access points, and other ceiling devices are often connected with a plug on the end of the in-wall cable instead of a jack and patch cord. This is the Modular Plug Terminated Link.
MPTL is recognized in the current copper standard. An annex defining the modular plug terminated link (MPTL) cabling topology and field test procedure has been incorporated into the recently published TIA-568.2-D Standard. It also has length limits. For both MPTL and permanent link, the maximum length of the horizontal cable shall not exceed 90 meters.
MPTL is not the same as crimping a standard patch cord plug onto solid cable. It uses field termination plugs designed for solid horizontal cable, and it should be tested with the MPTL procedure on a certification tester.
How to Test a Network Cable
Never assume a new cable works just because it clicked together. Test every cable before you use it.
Basic wire map test
A simple tester checks that each wire lands on the correct pin at both ends. Plug both ends into a cable tester and confirm that all 8 pins light up in sequence (1→1, 2→2, and so on). An out-of-order light means a wire is in the wrong position.
The limit of basic testers
A basic tester can miss real problems. A split-pair cable can show 8 connected conductors on a simple continuity tester and still fail a cable certifier. Split pairs happen when wires from two different pairs are placed where one pair should be. The pin order looks right, but crosstalk protection is lost.
Certification testing
For business networks, certification testing measures crosstalk, loss, length, and other parameters against the cable category. It is the only way to prove a link supports its rated speed. Our guide on [whether network cabling is hard](INTERNAL LINK) explains why certification separates professional work from basic DIY.
Troubleshooting Common Problems
No link at all: Check that both ends use the same color scheme and that every wire reaches the end of the plug or is fully seated in the jack.
Link works at 100 Mbps but not gigabit: One of the blue or brown pairs may be faulty. One guide notes the classic cause is a fault on the blue or brown pair — pins 4, 5, 7 or 8.
Intermittent drops: Look for a loose crimp, jacket not captured by the plug, or a plug crimped onto solid cable that has cracked.
PoE device won’t power on: Check all four pairs, confirm pure copper cable, and verify the run is within length limits.
Tester shows pins crossed: One end may be T568A and the other T568B. Re-terminate one end to match.
Common Mistakes and Misconceptions
Mixing T568A and T568B on one cable. This creates a crossover cable. Pick one scheme and use it everywhere.
Untwisting too much. Long untwisted sections increase crosstalk and cause certification failures. Keep untwist to half an inch or less.
Stripping insulation off individual wires. RJ45 plugs and IDC jacks pierce the insulation. Stripping wires causes poor contact and shorts.
Crimping standard plugs onto solid cable. Use keystone jacks for solid cable, or MPTL-rated plugs for direct device connections.
Leaving the jacket outside the plug. Without the jacket inside the plug, the strain relief cannot grip the cable and wires can pull loose.
Using mismatched parts. A Cat5e plug on Cat6A cable will limit performance and may not even fit.
Relying on a basic tester for business links. A wire map test confirms order, not performance.
Buying CCA cable. It is cheaper for a reason and can fail with PoE devices.
When to Call a Professional
Wiring a single patch cable or replacing one wall jack is a reasonable DIY task. Commercial projects are different. Call a licensed cabling contractor when:
- You need more than a few new runs or any work above ceilings
- Cables pass through plenum spaces, firewalls, or between floors
- The network supports POS, security cameras, access control, or business-critical systems
- You need certified test results for warranties or IT requirements
- The project involves fiber, shielded cable, or high-power PoE
- The job is large enough to require a California low voltage license
If you are in Carson, Long Beach, or the greater Los Angeles area, see our [Network Cabling Company Carson CA](INTERNAL LINK) and [Commercial Network Cabling Company in Carson, CA](INTERNAL LINK) pages to request a site survey.
Future Trends in Cable Termination
- More tool-free connectors. Field termination plugs and tool-less jacks are making consistent terminations faster.
- More direct-to-device links. MPTL is becoming common for cameras, access points, and building systems mounted in ceilings.
- Higher PoE loads. As devices draw more power, termination quality and pure copper conductors matter more.
- More Cat6A. New commercial projects increasingly specify Cat6A, which requires more careful stripping and termination than Cat6.
Key Takeaways
- Use RJ45 plugs on stranded patch cable and keystone jacks or patch panels on solid in-wall cable.
- T568B is the most common U.S. commercial standard: white/orange, orange, white/green, blue, white/blue, green, white/brown, brown.
- Use the same color scheme on both ends of every cable.
- Keep pairs twisted to within half an inch of the termination.
- Crimp plugs with the jacket inside the plug and every wire fully seated.
- Test every cable, and use certification testing for business networks.
- For commercial or multi-run projects, hire a licensed low voltage contractor.
Frequently Asked Questions
How do I wire a network cable?
Strip about an inch of jacket, arrange the eight wires in T568B order, trim them evenly, insert them into an RJ45 plug, and crimp. Wire the other end the same way, then test the cable.
What is the correct color order for an Ethernet cable?
For T568B, the order from pin 1 to pin 8 is white/orange, orange, white/green, blue, white/blue, green, white/brown, brown. T568A swaps the orange and green pairs.
Should I use T568A or T568B?
Either works if both ends match. T568B is the usual choice for U.S. commercial networks, while T568A is often specified for residential and government projects. Match whatever the building already uses.
Do I need to strip the individual wires?
No. Only strip the outer jacket. RJ45 plugs and keystone jacks pierce the wire insulation to make contact with the copper.
Can I put an RJ45 plug on solid cable?
Standard plugs are designed for stranded patch cable. Solid in-wall cable should terminate to keystone jacks or patch panels, or to plugs specifically rated for solid cable in an MPTL installation.
How much wire can be untwisted?
The TIA standard allows up to half an inch of untwisted wire at the termination point. For Cat6 and Cat6A, less is better.
Why does my cable work but only at 100 Mbps?
This usually means one of the blue or brown pairs is not connected properly. Gigabit Ethernet needs all four pairs, while 100 Mbps uses only two.
Do I need a special tool to wire a keystone jack?
Yes. Keystone jacks require a punch-down tool, usually a 110-style tool. RJ45 plugs require a crimp tool. The two tools are not interchangeable.