Cable testers

[DTSMAN]

Thanks to all who replied to stripping back cable jackets.
My company purchased a fluke DSP-2000 to use to certify cable. After two years of using it and still having network issues we put it through some in house test. Such as cutting wires in the middle, wire map fails, but all other test say pass. We also wrapped a cable around a neon sign and the tester passed it as well. Is there a high end tester that will let me know if I am picking up EMF from flouresent lights or other things that someone could reccommend. Thank You.

 

[daronwilson]

Well you may be encountering our little secret in the networking business. That secret is that not all the requirements of installation of data cabling are all that critical to actual function of the circuit.

I too have done some tests, pulled 90 pounds on the wire till it stretched, wrapped it around florescent light fixtures, tied it to high voltage wiring, etc. For the most part, short runs of good quality cable still passed in those situations. However, we never want to see it fail so the better the installation the safer we are. Would I go tell my installers that they can do all those things and it will be fine? Nope.

There are a few good testers on the market, you should get several opinions here, we use an HP Wirescope 350. Most of them will show you where (along the cable) the particular parameter was out of tolerance and which parameter caused the cable to fail the test. Of course there are many pitfalls, since we really only need 2 pairs for 100 mbs a wiremap failure on the white/brown pair will still get me 100baseT connectivity just fine. However excessive noise on one pair may couple to an adjacent pair and cause problems.

Your description of cutting wires in the middle then testing is interesting. My Wirescope won't test/certify if there is a wiremap failure. It makes you fix that first before you can go through the rest of the testing. Also I can save and graph each test result across whatever frequency range I am testing. For example, if I am doing Cat5e and want to look at the entire NEXT test to 100 Mhz, I can see that on a graph with all four pairs. If any pair is out of tolerance, it will show at what frequency it failed.

Regarding picking up EMF, the noise measurements should show excessive EMF, but only if it is out of the limits set forth for the cable and the network you are testing. The usual disclaimers apply such as making sure everything is turned on when testing, testing at different times if you have appliances that cycle automatically (HVAC units), and of course cable routing is important to protection from EMF.

I'm not familiar with the DSP-2000 but it looks as though it does test thru 155 mhz, question is does it check all the needed items for Cat5e certification?

Your post says you are still having network issues...that is a tough one. Many times we get called in to check one run of wire. I ask what the problem is and am usually told the user loses his Novell login several times a day. In many cases we've scanned the cable, replaced the fittings, replaced the cords, etc. with no evidence of any cable problem, yet they still have network 'issues'.

I'm sure others will chime in with their experience and recommendations as well.

Good Luck! It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[mikeydidit]

Daron is correct that the secret is out. Just because ANSI/TIA/EIA say's that it has to be this way, it will still work. (sometimes) I beleive that the tester you have is a good tester. I would get on the Fluke website and find their technical support. You may be able to get software upgrades for the unit that you have. They may also want you to recalibrate the unit that you have. I am not sure but I think you are supposed to have that done about once a year. I had a rep show me the latest greatest from Fluke the other day and it is a real nice unit. About $8000.00 worth. If you find any mistakes, please consider that they are there for a purpose. And everyone needs a purpose.
Hope this helps, Mikey.