Cat5e twisted pair interference/quality

[dgsmith]

We have had quite a large network install expansion over the summer, with the final ports now being terminated. Recently, we have increasingly been making our own "short" patch cables for the cab, as anything over half a metre (sometimes even half a metre cables themselves) look messy en-masse.

I was aware that the likelyhood of the cable quality being on par with that which you can buy professionally made was quite slim, however, we haven't seen any particular issues in doing this (especially with the very short ones).

However, i've been told that making cables yourself, especially any shorter than 0.5m (some of mine are 0.2/0.3) can have a noticeable negative impact in speed and reliability (due to length and interference). Whilst I don't doubt that it may cause some problems, is the degree which the signal degrades severe enough to contemplate buying in 100+ patch cables professionally made? We have bought some shielded cat5e cables for patching our servers, but specifically I was talking about desktops, most of which will have gig capability at nic and switch.

[powdarrmonkey]

Meh. Making your own is fine as long as you don't just string it together. Make sure the pairs are untwisted the smallest possible amount to get them into the plug, other than that there's nothing special about pre-fab cables (AFAIK).

What you've got to weigh up is whether it's more economical to spend the time making up 200 cables, or buying them at £0.30 a pop. I'd buy them

[Sylv3r]

We have just paid 28p each per 30cm cable of various colours to tidy up our cabinets with 1M, 2M and sometimes 3M cables from switch to patch panel. I have heard before about the quality of shorter cables but the ones I have bought will hopefully be a lot more reliable then anything I could have produced (wouldn't take much as I would soon loose patience when I got to cable number 5!).

[dgsmith]

We have just paid 28p each per 30cm cable of various colours to tidy up our cabinets with 1M, 2M and sometimes 3M cables from switch to patch panel.

28p each?? We have just paid some £2.60 from DABS for around 20 half metre STP coloured cables! Where did you get those from at that price and length? Even Misco do the UTP cables for 70p..

[Sylv3r]

28p each?? We have just paid some £2.60 from DABS for around 20 half metre STP coloured cables! Where did you get those from at that price and length? Even Misco do the UTP cables for 70p..

I got them from Insight

I think the half metre cables were less than 40p if I remember correctly for various colours.

[SYNACK]

Meh. Making your own is fine as long as you don't just string it together. Make sure the pairs are untwisted the smallest possible amount to get them into the plug, other than that there's nothing special about pre-fab cables (AFAIK).

What you've got to weigh up is whether it's more economical to spend the time making up 200 cables, or buying them at £0.30 a pop. I'd buy them

Agreed the main thing that you need to worry about is untwisting the wires as little as possible to prevent NEXT (Near end cross talk) any untwisted sections become small EMF (radio) transmitters. If you have multiple cables with much untwisted wire especially in close proximity like a cabinet the EMF can cause interference by being received on another slightly untwisted cable. So long as you keep the untwisting to the minimum required you will be completely fine with doing it by hand instead of purchasing.

The other thing to make sure of is that you are using patch type CAT6/5e because the wires in it are actually braided copper rather than solid core copper that is used in building wiring. The braided wiring is more flexible and terminates better into the rj45 plugs, the solid core can easily come loose from its contact points in the plug and become useless.

The patch grade stuff is good for lengths of up to 7m reliably but will attenuate the signal on longer runs making it less reliable due to its higher resistance.

[muppet]

Damn some of you guys type fast.... but my post still stands....

Sorry for HiJacking this thread, but.........
Where do you buy your cables from? I recently bought 50 x 0.5m cables from Cables&Stuff at 50p each, but obviously I would like to get them cheaper if I could......plus it might make peoples choices of making their own or buying them in a little easier.

[powdarrmonkey]

Seconded for Insight, under the Catalist arrangement (which of course covers other suppliers too).

[CyberNerd]

anything over half a metre (sometimes even half a metre cables themselves) look messy en-masse.

Take a look at some of teh cable management products here: CMS: The online YELLOW Book

there are plenty of devices designed to tidy up comms cabinets/datacentres, sometimes having very short cables makes it look much more untidy than having long cables that are properly routed.