Shielded Twisted Pair Without Ground? 1

[ibanez2727]

Hi All,

I am working on a project transitioning my office's phone system over to a new VOIP system---This will involve running some new wiring.

I have access to a supply of Shielded/UTP Cat5e wire (has a foil shield over the collection of pairs, but not each individual pair).

My experience with shielded wire is non-existent and everything I read mentions that the shield must be grounded in order for it to do anything.

Does anyone know of adverse effects of using this wire type like a standard UTP wire without grounding the shield?

 

[Robhub]

Your ungrounded shield is going to turn into an antenna - which will in turn induce RFI into your signal. You should only use STP cable if you're also installing shielded jacks and patch panels and do all the bonding and grounding necessary to make the system function properly. UTP is the best solution for this one.

 

[ibanez2727]

Bummer. Thanks for the info!

 

[buitenhek]

Robhub is correct about the antenna effect. But using STP for a typical UTP app may still work fine.
1. Do not ground either end, cut back foil but leave twist intact
2. Run a cable (in ceiling or on floor) to near max limit of 100 meters. Remember patch cords will be hooked at both ends.
3. Connect the unshielded RJ45 but pay particular attention to limiting the untwisting of the pairs.
4. Test with certified CAT5e tester. If it passes go to step five if not go to Graybar
5. Wrap 3 turns around a vacuum cleaner motor and see 4
6. Is it worth it? yes=go for install no=go to Graybar

Regards
Peter Buitenhek
ProfitDeveloper.com

"Never settle for a job well done...always look for cost cutting measures