Should I use screened or unscreened cable?
Part two – choosing the right cable construction
In our previous post, “Which data cable should I use for my network?”, we discussed the various categories of cable that are suitable for a home or office network installation and how to choose the right cable for the job. From Cat5e to Cat7, we outlined the basic differences and why you would pick one over the other. Hopefully, this has helped you to choose your cable category but now we are going to talk about the cable construction. Do you choose screened or unscreened cable?
Screened or Unscreened: What are U/UTP, U/FTP, F/UTP and F/FTP cables?
Once you have decided on which category to use you are confronted with another decision. U/UTP, U/FTP, F/UTP, or F/FTP? These letters describe the level of shielding on the wires within the cable to protect against crosstalk, alien crosstalk and electromagnetic interference (EMI), improving overall performance.
Each varies significantly in cost. Sometimes people choose the highest rated (and priced) cable construction thinking it will make for the best network when in fact, this only increases your costs.
All cables contain twisted pairs of cables inside:
- The first section of letters refers to whether all cables are shielded or unshielded.
- The second section of letters describes whether each ‘pair’ of cables is shielded or unshielded.
U/UTP: Unscreened /Unscreened Twisted Pair
From the image you can see that neither the pairs of wires nor the overall internal cable is shielded.
This is the basic construction you will find in Cat6. Cables near power cables can experience high levels of interference (EMI). When installed, the cable should be a minimum of 200mm away from any power source/high-voltage cable due to EMI.
U/FTP: Unscreened / Foil Twisted Pair
Most cat6A cable comes in this construction. The foil between the twisted pairs eliminates crosstalk and EMI. When the twisted pairs inside the cable are screened, they should be installed at least 50mm away from a power source/high-voltage cable.
U/FTP is advised when there is a low risk of external EMI and no sources of high power within 50mm.
F/UTP: Foil Screened / Unscreened Twisted Pair
This is most common in cat5e and Cat6 where the cables need to run near high voltage power cables or connect to machines that create high levels of EMI. The downside to this cable construction is that it creates greater crosstalk between the pairs. When the cable is screened the minimum distance from power is dropped down to 50mm.
F/FTP: Foil Screened / Foil Twisted Pair
This cable construction offers the best level of protection from internal crosstalk and external EMI/power interference, both of which can significantly slow down your network in certain environments. When the cable is screened the minimum distance from power is dropped down to 50mm.
F/FTP is advised when there is a high risk of external EMI or close proximity to high power.
Correct installation of FTP cable
We have seen a lot of installs in the past which have utilised a screened constructed cable that is not correctly terminated. There is a term called ‘bonding’ which refers to the earthing of the metal screen which protects the cable. The best practice is to have a clean ‘earth’ connection to which all screened cable should connect to. When this is not done, it can effectively make your cable an antenna that draws in EMI (Electromagnetic Interference). EMI will reduce your network speed and cause other problems within your network.
The best option for my home network data cabling system
As mentioned earlier, many people choose the most expensive cable construction, F/FTP, thinking this will provide the best performance when in fact, this highly engineered cable construction is built to shield the internal wires from potential EMI from machinery or power sources close by. With a carefully planned and installed data cable network, screened cable is not always required but often enough this is dictated by which data cable category you choose.
For future proof installs, choose Cat6A
If you are focused on installing a network that is future-proof (and will save you time and effort in years to come) then the slightly pricier Cat6A installation is your choice. Most cat6A cables come with a U/FTP construction, suitable if installed at least 50mm away from a power source/high-voltage cable.
Contact us today
If you are struggling with which category cable to use or need help with your final decision, get in touch. We are happy to help, advise or perform a survey and discuss carrying out the installation with your vision in mind.