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Using STP on LAN's

Using STP on LAN's

Using STP on LAN's

At my job, we've recently deceided to go from
UTP to STP in the 2-15 node LAN's that we build
for clients because of recent problems. Having disagreements with co-workers about Grounding.
I feel (from my limited electronical knowledge)
that it makes more sense to only use the shield at
one end of the cable, rather than possibly include a
potential between grounds in buildings electrical
wiring. I haven't seen a difference as of yet
either way. Does anyone have an answer?

RE: Using STP on LAN's

I may be wrong but I may be right. But I think when you ground two shields you create an antennae and this antennae will start to grab noise and other interference throughout the loop.

RE: Using STP on LAN's

Neff is correct. You do not want to ground both ends. This will only make the noise problem bigger. Ground only at the hub end. This way you can grab all the drains from the cable and wrap them together to ground them.

RE: Using STP on LAN's

I find it interesting that you are using STP when the TIA specs doesnt really support it and the gentleman who is the primary designer of the verious CAT levels doesnt recommend it. The biggest problem is that STP by itself doesnt do anything but cause serious installation issues. You need to use shield boxes, connector and so on for it really work right or it can make the problem even worse. The problem is in how TWP cancels out noise by allowing a certain amount of signal to "escape" from the wire and then cancel itself out on the return side. This is grossly simplified When you wrap a shield around the wire, unless it "Drains" correctly, it will introduce MORE noise into the signal by reflections then by the outside source.
Just for the record, Lucent CAT5 TWP and punch system was tested to 650Mhz for the European Market which up this point had insisted on STP due to emitted RF concerns. If wanted I can dig up the various links to papers and whatnot if you really want to pursue this. I had this same dicussion with the engineers at Siemens who were insisting that I install STP. After serveral "discussions" they relented and my TWP is working just fine.

Whitepaper by Paul Kish ( developer of CAT3,4,5)

White paper discussing UTP vs. STP and EMC directive

Standards Watch for Gig over UTP

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