What is a Drain Wire in Shielded Cable?
Why this Piece matters
If you’ve ever purchased shielded ethernet cable you’ll notice that there’s another piece to it you might not be familiar with. This extra strand sticking out of the cable is called a drain wire. Drain wires serve a specific purpose in shielded cable and it’s helpful to understand what they are. In this article we will cover what is a drain wire and the reason it’s there.
All About Drain Wires
As you may know it’s important to properly ground a shielded ethernet cable when deployed. The grounding of shielded cable helps in giving the shield proper effectiveness in protecting from EMI or signal interference. To assist with this some cables are designed with drain wires in addition to their shielding to make life easier. The drain wire in the cable makes it easier by giving it a way to ground the shield and provide shield continuity.
The way drain wires are used are with foil, nonmetallic and hybrid shields. They can also be seen with braided shields to simplify the termination of the shield ground.
How are they used?
In the structure of the cable you will see the drain wire running along the cable lengthwise next to the metallic part of the shield. Drain wires can be ran next to many different types of cables such as solid and stranded copper conductors. Each of those have their different purposes. Solid and stranded cable both come in unshielded and shielded versions which is why you might see a drain wire in the shielded version.
Final Thoughts
Drain wires are a great addition to make life easier in shielded cable. It’s important to know the type of drain wire when purchasing your networking cable. The termination needs of the source will decide whether the drain wire should be made of bare or tinned copper in stranded or solid construction.
