A twisted pair cable is a type of network cable made of two insulated copper wires twisted together to transmit data signals.
• The twisting helps in reducing interference and improves the quality of communication.
• It is the most widely used cable in Local Area Networks (LANs).
• The wires are twisted to reduce electromagnetic interference (EMI) from external sources.
• Twisting also reduces crosstalk, which is interference between adjacent wire pairs.
• This design ensures that both wires are affected equally by noise, allowing the receiver to cancel it.
There are two main types of twisted pair cables used in networking.
• UTP is a twisted pair cable that does not have any metallic shielding.
• It depends only on the twisting of wires to minimize interference.
• The twisting pattern reduces electromagnetic interference and signal loss.
• Since there is no shielding, UTP is lightweight and easy to handle.
• UTP cables are used in homes, offices, schools, and colleges.
• They are the standard cables for Ethernet LAN networks.
• UTP cables are low cost and affordable.
• They are easy to install, flexible, and lightweight.
• They support high-speed data transmission over short distances.
• UTP cables are more affected by electromagnetic interference.
• They are not suitable for environments with heavy electrical noise.
• UTP cables use the RJ45 connector.
• They follow T568A or T568B wiring standards.
• They mainly operate at the Physical Layer (Layer 1) of the OSI model.
• STP is a twisted pair cable that includes a metallic shield around the wire pairs.
• The shield provides extra protection against interference.
• The metallic shield blocks external electromagnetic noise.
• This ensures better signal quality compared to UTP.
• STP cables are used in industrial environments and data centers.
• They are suitable for places with heavy machinery or power cables.
• STP cables offer better protection from EMI and crosstalk.
• They provide more reliable and stable communication.
• STP cables are more expensive than UTP.
• They require proper grounding, which increases installation complexity.
• Grounding is mandatory for STP cables to work effectively.
• Improper grounding can reduce performance.
Key Differences Between UTP and STP
| Feature | UTP | STP |
| Shielding | No shielding | Metallic shielding |
| Cost | Low | High |
| EMI Protection | Moderate | Very high |
| Installation | Easy | Complex |
| Usage Area | Homes, offices | Industrial areas |
 |  |
• Twisted pair cables support short to medium distances.
• Performance depends on cable category (Cat5, Cat6, etc.).
• They are ideal for LAN environments.
• Twisted pair cables use copper wires.
• Interference is reduced mainly by twisting of wire pairs.
• UTP is the most commonly used LAN cable.
UTP → Cheap, common, office cable
STP → Shielded, strong, industrial cable
If interviewer asks:
👉 “Why do we use twisted pair cables?”
Answer confidently:
Twisted pair cables are used because twisting the wires reduces electromagnetic interference and crosstalk, making data transmission more reliable and cost-effective for LAN networks.
