More cat5 woes - CCA

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Whilst doing some dc loop resistance tests on some 'certified' cat5e cable I
found that green and orange pairs had 2x the expected resistance, and the blue
and brown pairs had 6x the expected resistance.
Close inspection revealed cooper clad aluminium with the copper thickness
varying depending on the pair....

Mike


Re: More cat5 woes - CCA

"Mike B"
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** The ratio of resistance for copper and aluminium of equal cross section
is 1:1.58

 Just how are you measuring the resistance ?



....  Phil





Re: More cat5 woes - CCA

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Two different multimeters give the same results.

I have two cables running in the same conduit side by side for about 45m.
One is AUSTEL approved, the other 'UL certified'. The only connections are to a
solder tag patch panel (no punch down block) and a crocodile lead to do the
loopback.

The AUSTEL approved cable gives 11 Ohm loopback for the green, orange, blue and
brown pairs which sounds about right.
The other cheaper 'UL certified cable'  gives 25, 25, 68 and 68 Ohms.


Mike

Re: More cat5 woes - CCA

"Mike B"
 "Phil Allison"
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** Sorry, "  multimeters "  is not enough detail.

Digital multimeters are likely to mis-read badly ( usually waaay high) in
the presence of contact resistance or AC hum.  Try an old fashioned analogue
meter.

If the numbers are not the same  -  be afraid.

Be very afraid.

Whatever the real problem   -  it is NOT due to the ratio of copper to
aluminium.



....  Phil





Re: More cat5 woes - CCA

:Whilst doing some dc loop resistance tests on some 'certified' cat5e cable I
:found that green and orange pairs had 2x the expected resistance, and the blue
:and brown pairs had 6x the expected resistance.
:Close inspection revealed cooper clad aluminium with the copper thickness
:varying depending on the pair....
:
:Mike

What does "certified" mean and by whom was it certified? Did it have the A-tick
symbol? What was the brand of cable which had copper-clad aluminium conductors?

Section 5.6.6.1 of this document
http://www.commsalliance.com.au/__data/assets/pdf_file/0008/2420/S008_2010.pdf
gives the Australian requirements for approved telecommunications cables. Other
than coax, which is permitted to use a copper-clad aluminium centre conductor -
provided the centre conductor is at least 2mm in diameter, all other cables must
be either plain copper or plated (tin) copper. Table 3 gives the resistance
requirements.

Re: More cat5 woes - CCA

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The label says 'NETCONNECT CAT5e CABLE E138034 1300 24AWG' which appears to be
the UL number.

Re: More cat5 woes - CCA

"Mike B"

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** Have you seen this ?

http://en.wikipedia.org/wiki/Category_5_cable#Copper-clad_aluminium



....  Phil



Re: More cat5 woes - CCA

:
:>
:>:Whilst doing some dc loop resistance tests on some 'certified' cat5e cable I
:>:found that green and orange pairs had 2x the expected resistance, and the
blue
:>:and brown pairs had 6x the expected resistance.
:>:Close inspection revealed cooper clad aluminium with the copper thickness
:>:varying depending on the pair....
:>:
:>:Mike
:>
:>What does "certified" mean and by whom was it certified? Did it have the
A-tick
:>symbol? What was the brand of cable which had copper-clad aluminium
conductors?
:>
:
:The label says 'NETCONNECT CAT5e CABLE E138034 1300 24AWG' which appears to be
:the UL number.


That cable is definitely a Chinese knock-off and is not UL certified.

NETCONNECT is a proprietary trade name of AMP (Tyco). Here is the data sheet for
their genuine Cat 5e cable. Note this is UL certified with the same number as on
your Chinese cable.
http://www.ampnetconnect.com/documents/Enhanced_Cat_5e_Cable_Cut_Sheet.PDF

Re: More cat5 woes - CCA

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If you believe http://www.connectingindustry.com/story.asp?storycode19%4288
20% of the cable entering the UK is counterfeit.

Half way down the page it says, "Counterfeit cables can even have copper-coated
steel or aluminium conductors in place of copper, ".

The resistance measurements of my cable would suggest that 2 of the 4 pairs are
copper clad steel :-(



Re: More cat5 woes - CCA

"Mike B"
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** Is it obviously magnetic ??

 Steel has about 7 times the resistance of copper.


.....  Phil



Re: More cat5 woes - CCA

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The brown pair stick to a magnet :-(
The green and orange pairs do not.
I don't have any spare blue pair to test.

Well there you go. Fake UL certified cat5 copper/aluminium and copper/steel.


Mike

Re: More cat5 woes - CCA

"Mike B"
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** A cheap Chinese cat with no pedigree .....

    Meeeoooooowwwwwwww.....


.....   Phil



Re: More cat5 woes - CCA

:
:>
:>"Mike B"
:>>
:>> If you believe
:>> http://www.connectingindustry.com/story.asp?storycode19%4288
:>> 20% of the cable entering the UK is counterfeit.
:>>
:>> Half way down the page it says, "Counterfeit cables can even have
:>> copper-coated
:>> steel or aluminium conductors in place of copper, ".
:>>
:>> The resistance measurements of my cable would suggest that 2 of the 4
:>> pairs are
:>> copper clad steel :-(
:>
:>
:>** Is it obviously magnetic ??
:>
:> Steel has about 7 times the resistance of copper.
:>
:
:
:The brown pair stick to a magnet :-(
:The green and orange pairs do not.
:I don't have any spare blue pair to test.
:
:Well there you go. Fake UL certified cat5 copper/aluminium and copper/steel.
:
:
:Mike


I see that in the USA they have instituted a laser holographic product labelling
system for UL certified cable.
http://www.metacafe.com/watch/6035316/cat5e_cable_new_anti_counterfeit_ul_label /

This might be of use to cabling contractors who buy bulk cable but for the
hobby/small user who only buys a few metres off the roll at some unscrupulous or
ignorant supplier, he could still get caught.

I have asked Communications Alliance http://www.commsalliance.com.au/ if they
are aware of the problem and if there are plans to institute a similar labelling
scheme here.

Re: More cat5 woes - CCA
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The bad effect of this substandard cable over short runs in homes
might be relatively
insignificant compared to long runs, especially in noisy or such
"unfriendly" environments, and/or in large commercial
 buildings where a signal might go through several very long runs of
this crap cable to get from point A to B,
and/or might have a substantial load on it from multiple users. - all
these are unlikely situations for a hobbyist / home install.

I guess at the end of the day, you have to buy from reputable
suppliers, and test it before installing it in a situation where it
will
be very difficult to replace it if there are found to be problems.


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Re: More cat5 woes - CCA

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Will power over ethernet work when the resistance is 7x the expected?

Linksys are marketing their POE adaptor kit to home users
http://homesupport.cisco.com/en-us/wireless/lbc/WAPPOE
This one operates at 48v so it might still work.

Re: More cat5 woes - CCA
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  depends on the distance and the required trigger voltage

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yup
  I metered some clipsal titanium cat6 cable , 8.0 Ohms over 120 metres


--
X-No-Archive: Yes


Re: More cat5 woes - CCA
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depends also on how much current the device being powered by it draws
too.

Re: More cat5 woes - CCA

:Whilst doing some dc loop resistance tests on some 'certified' cat5e cable I
:found that green and orange pairs had 2x the expected resistance, and the blue
:and brown pairs had 6x the expected resistance.
:Close inspection revealed cooper clad aluminium with the copper thickness
:varying depending on the pair....
:
:Mike

Mike, can you tell me where you got this cable from?

email me direct if you would like to divulge this info.

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