Question on CAT6 cable

[pirate]

Here is a pic of a CAT6 cable. usual pairs, plastic wrap, foil wrap, draw-cord, plastic separator...and a bare copper wire, which may be cca, i'm not sure...but what is that bare wire used for?

 

[DPG]

Is it a drain wire, connected (by contact) to the foil screen?

 

[dodger421]

It’s for splitting the sheath like that bare wire in a T+E that you just cut off afterwards right? ?

Seriously though I think DPG might be on to something, maybe a way of providing a ground connection for the foil “shielding”.

Edit - it is a drain wire according to this RS Data Sheet

https://docs.rs-online.com/70fc/0900766b8157d0ae.pdf

 

[pc1966]

Mostly network cable is UTP = unscreened twisted pair. This is screened, but to get any benefit from the screen it needs to be earthed, and that is what the drain wire is for.

If you don't believe me, just try connecting to the aluminium foil....

 

[pirate]

Thanks for all your thoughts, and it is clear that wire is a drain. I don't use this type normally, just the usual UTP. I thought the aluminium screen was just that, a screen, and hadn't thought about its functional connection.

 

[James]

Unless a screen is bonded to ground, it is in fact an aerial

 

[pirate]

Aha...like a TV coax cable, which IS an aerial!

 

[DPG]

Aha...like a TV coax cable, which IS an aerial!

Theoretically a length of coax would be an ideal transmission line and pass 100% of the signal from the aerial to the TV, with no loss or leakage. Obviously in reality there are losses and small impedance differences. Smith chart anyone?

 

[pc1966]

You can get deliberately leaky coax for distributing wifi/mobile signals in underground tunnels, etc.

 

[pirate]

Really? I had no idea. I must do some research...

 

[pirate]

Smith chart? Please elucidate, every day's a school day...
(Not at the moment, obviously...)

 

[DPG]

Smith chart? Please elucidate, every day's a school day...
(Not at the moment, obviously...)

It's a circular graphing system used for impedance matching in RF systems. Did them on my HND but wouldn't know how to create one now!