Structured Cabling: T568A & T568B Standards
T568A & T568B Pinouts
Pin Configuration
- 1: Green (T568A) / Orange-White (T568B)
- 2: Green-White (T568A) / Orange (T568B)
- 3: Orange (T568A) / Green-White (T568B)
- 4: Blue (T568A) / Blue (T568B)
- 5: Blue-White (T568A) / Blue-White (T568B)
- 6: Orange-White (T568A) / Green (T568B)
- 7: Brown-White (T568A) / Brown-White (T568B)
- 8: Brown (T568A) / Brown (T568B)
Cable Usage
- Pair A: Telephone
- Pair 2: Ethernet Reception
- Pair 3: Ethernet Transmission
- Pair 4: Control
Connection Methods
Two primary methods connect telecommunications closets:
Direct Connection (Interconnection)
Suitable for small systems, this method directly connects the patch panel to the active device with a single cable. While saving a panel, it requires all connections to run directly from the equipment room. This is commonly used to connect a computer to a hub or switch.
Cross-Connect
This method connects panels using patch cords without directly accessing equipment ports. Chosen during the design phase, it’s crucial for scalability as cabinet numbers and infrastructure requirements may change. This method connects two PCs, hubs, or switches.
Patch Panels
Patch panels feature RJ45 jacks on the front and 110 IDC connections at the rear. Panel, rack, and cabinet components should be mounted as per design specifications. Patching cabinet composition, based on wiring design, occurs after cabinet placement and cable bundle insertion. Matching grommet and patch panel rack unit sizes is recommended.
Grommets
Cable bundles for each connection panel should hold approximately 110 connectors. Proper cable identification and connection type are crucial during installation. Maintain proper cable curvature for easier administration, maintenance, and modifications.
Cabinets
Telecommunications cabinet composition should be determined during design. General guidelines for a small to medium-sized cabinet include:
- Place heat-producing equipment at the back for better heat dispersion.
- Position fiber optic panels higher to minimize dust exposure from fans.
Larger systems may require separate cabinets for telephony and data. Large installations can use wall-mounted 110 IDC panels for voice, reserving cabinets for data services, saving costs and simplifying maintenance and expansion.
Cabinet Usage Tips
Telecommunications cabinets (racks) use units of approximately 45mm. Recommended cabinet characteristics include:
- Ample space for cable passage and management (at least 600x800mm).
- Accessibility from all sides.
- Support for cataloged accessories.
- Lockable door.
Wires typically enter from the rear. Both backbone and horizontal cable bundles should be placed at the bottom of containers, secured to rear studs. Proper vertical stack arrangement is crucial to prevent cable weight from stressing lower connections. Avoid cutting cables to exact lengths; extra length simplifies patch panel connection.