When it’s installed badly or it is cabled in CCA (Copper Coated Aluminium)
Due to the global shortage of copper we are finding an increasing number of CCA cable installed as a replacement for Cat5e copper cable by electricians because it cheaper. CCA uses an aluminium conductor that is coated with copper but has higher attenuation properties and is not recognised within the communications industry’s Cat5e or Cat 6 standards. CCA is not a copper conductor and therefore has different properties to copper that can result poor network performance because more packets of data having to be retransmitted when it is corrupted or lost at the physical layer. The effect will be especially prevalent when your network runs exceed 75m due to attenuation and at best will lead to slower network for most users.
More concerning is the use of Power over Ethernet (PoE) over CCA networks which brings about some worrying possibilities due to a real threat of over heating, particularly in applications such as IP CCTV where power is drawn through the network 24/7/365. There is a very real possibility heat will build up faster than it can be dissipated leading to potentially disastrous consequences.
Some UK suppliers are also selling CCA patch cables to their customers and although performance has not yet been documented, problems are likely to become apparent as organisations upgrade their networks to gigabit or PoE.
You can certify your network installation will be 100% copper by using an authorised system installer. Your installer will only use CAT5e cable which is tested, CE certified and held to industry standards. Your authorised installer can offer 25 year warranty on your network backed by the manufacturer. Beware of imitations.