RJ45 Connector: Everything You Want to Know


If you’re a beginner to network installation, I guess you will be confused about terms such as RJ45, 8P8C, and modular plug. All of these terms are related to items that are attached to the end of Ethernet cables. We’re talking about all things about RJ45 connectors here to let you have a better understanding of them.

What is “RJ45”?

Do you know the meaning of “RJ45”? Let me explain it.

“RJ” is the abbreviation of “registered jack”, which originally means a standardized telecoms network interface for voice and data devices connection. It was first defined in the USCO (Universal Service Ordering Code) of Bell System and in the 1970s, it was licensed by FCC (Federal Communications Commission) to maintain the compatibility between customer devices and telephone service provider equipment. “45” means the listing number of networking interface standards.

What is an RJ45 Connector? RJ45 vs. 8P8C?

There are different types of modular connectors for telephone and network applications and the RJ45 is one kind of modular plug used in the network.

In fact, the RJ45 connector is a technically incorrect term, and the correct way to call it is “8P8C modular plug”. “8P8C” refers to “8 Positions and 8 Contacts”, which is often used at the end of Ethernet cables. A network patch cable is usually made of an Ethernet cable and two RJ45 connectors on both ends.

rj45 connector


This tiny network connector is made of several important parts.

The two main parts of RJ45 connectors are the plastic housing and gold-plated contacts. A good-quality Ethernet connector usually features a plastic housing made of high-performance PC materials. It also features eight channels and gold-plated contacts to make a contact with eight wires in the Ethernet cable.

There are two types of gold-plated contacts: two-prong and three-prong contacts. RJ45 connectors with two-prong contacts are designed for stranded cable wires, whereas three-prong connectors can be used in both solid and stranded wires. Three-prong connectors can help well fix the cable wire for a stable connection.

A network connector comes with a strain latch and retaining latch. The strain latch is designed to make the RJ45 connector snap in the interface and avoid being loose. Most Ethernet connectors feature a strain latch and rectangular hole and if you use these connectors, you need to use the specific crimping tool. The retaining latch is designed to fix the network cable and prevent it from falling off. Remember to press the retaining latch when inserting or pulling out the modular plug.

For some scenarios full of EMI and RFI, shielded RJ45 connectors are used and they feature a metal shielding structure to help avoid interference.

Different RJ45 connectors have different types of insulated conductor holes. Eight insulated conductor holes of Cat5 connectors are arranged neatly, while Cat6 connectors generally have a staggered pin layout. But this is not the standard and it depends on different manufacturers.

RJ45 Connector Pinout

As is known to all, RJ45 connectors are made to connect Ethernet cables. There are two wiring standards for terminating network cables with RJ45 connectors: T568A and T568B. The main difference between these two color codes is the interchange of orange and green wires. T568B is more popular than T568A, but either one is OK according to your own requirement.

t568a vs t568b

RJ45 Connector Types

To meet different needs of network installation, RJ45 connectors can be classified into various types. There are Cat5e connectors, Cat6 connectors, Cat6a connectors, Cat7 connectors that are designed to be compatible with different categories of network cables. RJ45 connectors can also be divided into other types according to applications and designs. Do you know the types of RJ45 connectors? Read on to know more details.

Regular vs Pass-through RJ45 Connectors

Standard RJ45 connectors can also be named as non-pass-through RJ45 connectors, which are usually referred to as 8P8C modular plugs. Pass-through RJ45 connectors allow the network cable wires to pass out of the connector body. Compared to standard RJ45 connectors, pass-through RJ45 connectors are easy to keep Ethernet cable wires aligned before terminating connectors. In addition, pass-through RJ45 connectors are easier to operate, ideal for novices or DIYers. Pass-through RJ45 connectors usually require a specific crimping tool.

#Tips: Angled flush cutting makes it easier to install both non-pass-thru and pass-thru connectors.

standard rj45 connector vs pass through rj45 connector

Shielded vs Unshielded RJ45 Connectors

Unshielded RJ45 connectors have a plastic housing, while shielded RJ45 connectors usually feature a metal shield to avoid too much electromagnetic interference (EMI).

The metal shielding structure is usually plated with nickel or gold. But nickel-plated shielding structure is more common on the market.

Remember not to use a shielded RJ45 connector on an unshielded network cable as it may affect the connection. Shielded RJ45 connectors are often paired with shielded Ethernet cable for maximum performance. If you use an unshielded cable, choose an unshielded connector and if the cable is shielded, use the shielded RJ45 connector.

Standard vs Toolless RJ45 Connectors

Standard RJ45 connectors usually require a professional tool - RJ45 crimping tool. A toolless RJ45 connector or field termination plug can be easily terminated without a crimping tool.

Toolless connectors can be used in emergent situations and field termination. For example, they are designed for quick connection in the field and frequently moved cabling. What’s more, toolless RJ45 connectors can also be reused a few times without affecting the data transmission.

standard rj45 connector vs toolless rj45 connector

Single-piece vs Two-piece RJ45 Connectors

Compared to single-piece RJ45 connectors, two-piece RJ45 connectors have an additional load bar, designed to help align eight wires for easy and quick wiring. In addition, the load bar can also improve RJ45 connectors’ resistance to interference.

Single-piece RJ45 Connectors vs Two-piece RJ45 Connectors

The Inner Working Principle

When you connect the RJ45 connector to the end of the Ethernet cable and plug it into the Ethernet port, do you know how it works?

There are eight gold-plated contacts inside an RJ45 network connector and each one is separated by insulating plastic materials. Some connectors feature two-prong contact pins and some come with three-prong contact pins. These prongs will “bite” into every wire when the RJ45 connectors are pressed by a crimping tool. Once the RJ45 network connector is placed into the Ethernet port, the female and male connectors will make a contact with each other. Then, data and signal transmission began to flow through the Ethernet cable.


Never underestimate the power of these tiny things. These connectors can be used to connect a computer to a server, router, TV, or any other device to make a local area network. RJ45 connectors are essential parts in the cabling system, which are often used in the large data center or server rooms of the company. Besides, they can also be used in the factory such as Industrial Process Control and Quality Control Systems. These Ethernet connectors allow for stable, high, and secure data transmission when you make the system connect to the Internet.

rj45 connector application