One of the most common types of cable you might find are shielded cables. Shielded cables are a necessity for some applications.
Types of cables that come in shielded versions include Ethernet cables, coaxial cables, HDMI cables, and many more.
What is a shielded cable?
A shielded cable is a cable that comes with an extra layer of protection surrounding the wires, before the insulation and outer PVC covering are applied.
This layer is usually made of a metal foil material or metal braiding.
Unshielded Twisted Pair
If a cable is referred to as “UTP” or “Unshielded Twisted Pair”, this means it has no additional shielding.
Shielded Twisted Pair
“Shielded twisted pair” or “STP” cable is a standard reference to shielded cable. This means a metal foil material is surrounding the group of internal wires. This term usually applies to Ethernet cables.
The shielding can be applied to each individual wire, which is referred to as “foiled twisted pair” or “FTP”. This provides an added layer of protection beyond standard shielding. This term applies to Ethernet cables, as well.
Typically, shielded coax cables come with a tubular metal shield that surrounds the entire group of internal wires. It can be braided or solid.
Braided shielding allows the cable to be more flexible than those with its solid counterpart, but it also leaves more openings in the shield for electromagnetic interference to penetrate.
Shielded HDMI Cables
HDMI cables can be shielded, as well. This is done much like the shielded twisted pair Ethernet cables, where a solid foil shield is applied to the group of inner wires.
Why Use Shielded Cable and Keystone Jacks?
If you are using shielded cable, you will also want to employ the use of shielded connectors and keystone jacks to ensure maximum protection.
Using shielded cables helps protect against electromagnetic interference and radio frequency interference. This is usually only necessary where cables will be run very close to other cables or electronic devices.
In security systems, this can help prevent false alarms generated by interference.
For audio applications, shielding can help reduce noise and static in the projected sound.
In most home applications, shielded cables are not necessary. The amount of EMI or RFI is minimal.