Ethernet Cable Color Order: The Complete Wiring Guide (T568A vs T568B)
The standard Ethernet cable color order follows two wiring schemes — T568A and T568B — defined by the TIA/EIA-568 standard. T568B is the most widely used in the United States for home and commercial installations, while T568A is preferred in government and some international settings.
Whether you’re terminating a keystone jack, punching down a patch panel, or crimping an RJ45 connector for the first time, understanding the correct Ethernet cable color order is the difference between a network that flies and one that frustrates. This guide breaks down both standards, when to use each, and exactly how to wire them — drawn from hands-on cabling experience in residential, SMB, and enterprise environments.
What Is the Ethernet Cable Color Order?
Inside every Cat5e, Cat6, or Cat6A cable are four twisted pairs — eight individual conductors — each wrapped in a distinct color-coded jacket. The Ethernet cable color order determines which wire lands on which pin of your RJ45 connector or keystone jack. Getting it wrong means no link, intermittent drops, or reduced speeds.
The two dominant wiring standards are:
- T568B — the de facto standard in North American commercial and residential wiring
- T568A — used in government installations (per FCC and certain federal specs) and for crossover cables when paired with T568B on the opposite end
T568B Color Order (Pin-by-Pin)
T568B is what most electricians, IT techs, and DIYers in the US reach for by default. Here’s the exact pin order:
| Pin | Color | Function |
|---|---|---|
| 1 | Orange/White | TX+ (Transmit +) |
| 2 | Orange | TX− (Transmit −) |
| 3 | Green/White | RX+ (Receive +) |
| 4 | Blue | Reserved / PoE |
| 5 | Blue/White | Reserved / PoE |
| 6 | Green | RX− (Receive −) |
| 7 | Brown/White | Reserved |
| 8 | Brown | Reserved |
Memory trick: “O/W, O, G/W, BL, BL/W, G, BR/W, BR” — orange leads, then green splits around the blue pair.
T568A Color Order (Pin-by-Pin)
T568A simply swaps the orange and green pairs compared to T568B:
| Pin | Color | Function |
|---|---|---|
| 1 | Green/White | TX+ |
| 2 | Green | TX− |
| 3 | Orange/White | RX+ |
| 4 | Blue | Reserved / PoE |
| 5 | Blue/White | Reserved / PoE |
| 6 | Orange | RX− |
| 7 | Brown/White | Reserved |
| 8 | Brown | Reserved |
T568A vs T568B: Which Standard Should You Use?
This is the most common question when wiring an RJ45 connector, and the answer depends on context:
Use T568B when:
- Wiring a home network from scratch
- Installing in a commercial office or business environment
- Connecting to existing infrastructure (match whatever is already in place)
- Working with most pre-made patch cables (they’re almost always T568B)
Use T568A when:
- Working on US government or federally funded projects (required under certain FCC premises wiring rules)
- Building a crossover cable (wire one end T568A, the other T568B)
- The existing building infrastructure already uses T568A
Critical rule: Both ends of a straight-through patch cable must use the same standard. Mixing T568A on one end with T568B on the other creates a crossover cable — useful for directly connecting two computers, but it will kill a standard router-to-device connection.
Comparison Table: T568A vs T568B at a Glance
| Feature | T568A | T568B |
|---|---|---|
| Pin 1–2 pair color | Green | Orange |
| Pin 3, 6 pair color | Orange | Green |
| US residential use | Less common | Standard / preferred |
| Government use | Recommended (FCC) | Not specified |
| Crossover cable | One end (with T568B other end) | One end (with T568A other end) |
| Pre-made cables | Rare | Nearly universal |
| Backward compatible | Yes (with T568B infrastructure) | Yes (with T568A infrastructure) |
How to Wire an RJ45 Connector: Step-by-Step
Here’s how I wire an RJ45 following T568B — the process I’ve used on hundreds of drops:
- Strip the outer jacket about 1.25 inches using a cable stripper — don’t nick the inner conductors.
- Untwist each pair carefully. Maintain as much twist as possible right up to the connector entry point; excessive untwisting degrades crosstalk performance on Cat6 and above.
- Arrange wires in the T568B order: O/W, O, G/W, BL, BL/W, G, BR/W, BR — left to right when the RJ45 clip faces down and the opening faces you.
- Trim the wires to about 0.5 inches so they’re even and fit cleanly into the connector channels.
- Seat the wires fully into the RJ45 — each conductor should reach the front of the plug and make contact with the gold pins.
- Crimp firmly with an RJ45 crimping tool.
- Test the cable with a cable tester to verify continuity on all 8 pins.
Understanding Twisted Pairs and Why Color Coding Matters
The eight wires inside an Ethernet cable are grouped into four twisted pairs. Each pair twists at a slightly different rate (called the “lay length”) to cancel electromagnetic interference — a technique called differential signaling. The color coding isn’t cosmetic; it maps directly to these functional pairs:
- Pair 1: Blue / Blue-White
- Pair 2: Orange / Orange-White
- Pair 3: Green / Green-White
- Pair 4: Brown / Brown-White
In both T568A and T568B, the pairs carrying active data (TX and RX) are Pairs 2 and 3. Pairs 1 and 4 (blue and brown) are used for Power over Ethernet (PoE) in IEEE 802.3bt (4-pair PoE) or left unused in older 10/100 Mbps networks.
Mismatching a twisted pair — say, putting orange on pin 1 and orange/white on pin 3 instead of keeping them together — creates a split pair. Split pairs pass a basic continuity test but cause severe crosstalk that tanks performance, especially at Gigabit speeds. This is a common wiring mistake that’s notoriously hard to catch without a proper cable certifier.
Cat5e vs Cat6 vs Cat6A: Does the Color Order Change?
No. The Ethernet cable color order is identical across Cat5e, Cat6, Cat6A, and Cat8. T568A and T568B apply universally regardless of cable category. What changes between categories is the cable construction (tighter twists, thicker conductors, internal splines in Cat6), not the wiring standard.
| Cable Category | Max Speed | Max Distance | Color Order Standard |
|---|---|---|---|
| Cat5e | 1 Gbps | 100 m | T568A or T568B |
| Cat6 | 10 Gbps (short) | 55 m (10G) | T568A or T568B |
| Cat6A | 10 Gbps | 100 m | T568A or T568B |
| Cat8 | 25/40 Gbps | 30 m | T568A or T568B |
PoE and the Role of the Blue and Brown Pairs
Power over Ethernet (PoE) has changed how the blue and brown pairs are used. Under IEEE 802.3af/at (2-pair PoE), power runs over the same pairs as data — pins 1/2 and 3/6. Under IEEE 802.3bt (4-pair PoE, also called PoE++), all four pairs carry power simultaneously, which is why correct wiring of the blue and brown pairs matters for devices like 60W and 90W PoE access points, PTZ cameras, and digital signage.
Sloppy wiring that puts brown-white on pin 7 and brown on pin 8 reversed won’t affect a standard data link at all — but it can cause issues with PoE power delivery from some switches. Wire it right the first time.
Common Mistakes When Following the Ethernet Cable Color Order
From troubleshooting field installs, these are the errors that show up most often:
1. Split pairs — Mixing conductors from different pairs (e.g., orange on pin 1 with green-white on pin 2). The link will work at 10/100 but fail or degrade at Gigabit.
2. Mismatched standards — T568A on one end and T568B on the other, accidentally creating a crossover cable.
3. Excessive untwisting — Untwisting more than half an inch of each pair before termination. This is especially damaging in Cat6 runs.
4. Not seating wires fully — If wires don’t reach the front of the RJ45, the crimp won’t make solid contact with all 8 pins.
5. Relying on color alone without testing — Cable colors can fade, vary by manufacturer, or get confusing under poor lighting. Always test with a wire map tester after terminating.
FAQ: Ethernet Cable Color Order
What is the standard Ethernet cable color order?
The two standard Ethernet cable color orders are T568B (Orange-White, Orange, Green-White, Blue, Blue-White, Green, Brown-White, Brown) and T568A (Green-White, Green, Orange-White, Blue, Blue-White, Orange, Brown-White, Brown). T568B is the most commonly used in the United States.
Does it matter which wiring standard I use — T568A or T568B?
It matters only in two situations: (1) you must match whatever standard is already in your building or on your existing patch panels, and (2) both ends of any straight-through cable must use the same standard. For new installations with no existing infrastructure, T568B is the safe default for US residential and commercial work.
What happens if Ethernet cable wires are in the wrong order?
If the wires are in a completely wrong order, the cable will have no link. If you’ve created a split pair by mixing conductors from different twisted pairs, the cable may appear to work but will have degraded performance — often showing up as packet loss, reduced throughput, or failure to negotiate Gigabit speeds.
What color wires carry data in an Ethernet cable?
In both T568A and T568B, the orange pair (pins 1–2) and green pair (pins 3 and 6) carry the active transmit and receive data signals. The blue and brown pairs (pins 4–5 and 7–8) are used for PoE power delivery or are reserved.
How do I remember the T568B color order?
A reliable mnemonic: start with orange (O/W, O), skip to green-white on pin 3, insert the blue pair (BL, BL/W) on pins 4–5, close with green on pin 6, then finish with the brown pair (BR/W, BR). Orange leads, green splits, blue fills the middle.
Can I use T568A and T568B on the same network?
Yes — as long as each individual cable is terminated consistently on both ends. A network can have some runs wired T568A and others T568B without any issue, because the wiring standard doesn’t affect the signal — it only defines which physical pin each pair connects to. The problem only arises when a single cable has mismatched standards on each end.
Final Thoughts
The Ethernet cable color order isn’t arbitrary — it’s a precision specification that affects signal integrity, PoE performance, and long-term network reliability. T568B is your default for virtually all US installations; T568A is for government work and crossover scenarios. Keep your pairs twisted tight, seat your wires fully, and always test after terminating. A $20 cable tester saves hours of troubleshooting.
