Low cost cable testers?
Question
Is there a low cost unit that will test all of the tests you talk about?
ACR, Time Domain Reflectrometry (TDR), Near End Cross Talk, Power Sum Near
End Cross Talk, Far End Cross Talk (FEXT), or can you give me a list of units to
buy? and is there a way to test with a meter? if so how?
Answer
Thanks for your email. Unfortunately there is no low cost unit that will test all the
parameters required to certify a cable to Cat 5e/6/7 standards. In my opinion, the
best cable testers on the market are the Fluke and the MicroTest cable scanners.
If you only need to test a few cables or if this is a one off job you may be able to hire one for a week or
two relatively cheaply.
Another point is that if you are an IT manager and responsible for a sites network, the Fluke would be
the better option as it can also perform some Ethernet tests as well, things like traffic monitoring and I
think it also monitors collisions.
Two jacks per cable?
Question
Our offices are moving into an existing building which was wired by the previous owners, or a
contractor for them, and their wiring is one I have never seen before. Each wall outlet has two data
jacks which are "sharing" a single UTP cable, 2 pairs to the left jack and the other two pairs to the right
jack. What problems are we likely to encounter with this setup? Our normal wiring method is one jack
one cable.....
Answer
It sounds like costs were an issue when this building was cabled, but if it is configured for Ethernet
(using pins 1, 2, 3 & 6) it should be OK for 10BaseT. I wouldn't like to speculate on whether it will run at
higher speeds because that is dependent on the quality of the installation and the amount of network
traffic.
If the installation was originally wired for Token Ring then it will use pins 3, 4, 5 & 6 which will not work
with Ethernet.
Crosstalk could be an issue if the pairs have been split between outlets and/or between pins on the
jack, (pins 1 & 2 should be a pair and 3 & 6 should be a pair).
I hope this helps, and although it is possible that you will have no problems, I would strongly advise a
rewire. This is because it will be easier at this time to carry out the work and, as you move to higher
speeds in the future this wiring configuration will undoubtedly start to cause problems.
Whats the difference between stranded and solid cabling?
Question
I just found your web site and i thought that it was very informative, but i could not find any thing on the
difference between stranded and solid cabling, could you tell me what the difference between them is?
(I think stranded is used as patch leads and solid is used as a connector between the patch panel and
the wall outlet).
Answer
You are correct, stranded cable is used for patch leads because it is more flexible than solid copper.
The solid cable is used in the fixed part of the installation, ie. the cable between the patch cabinet and
the wall outlets. Solid cable has better performance characteristics than stranded and it is cheaper to
make.
Question
Thank you for your help, it was very useful. One other thing you could help me with, is the way that the
solid and stranded cable are wired up different? because i know that you can get RJ45 plugs for solid
and stranded cable (i know how to wire up stranded cable to a RJ45 plug), if so then how is the solid
cable wired up to the RJ45 plug.
Answer
The colour codes are the same for solid and stranded cables, the difference is in the IDC (insulation
displacement connector) in the RJ45 plug. Because the cores are different the contacts have to be
slightly different to ensure a good contact is made.
Pricing for a cabling installation?
Question
I am doing some research and am looking for information on pricing for a cable installation. For
instance do you have a flat rate per drop installing Cat 5 or fiber or do you charge per feet? Also what
is the going rate for this type of installation including wall plates and cable. Any information you can
give me on this would be very helpful in my research!
Answer
It is normal to price a job on a per drop basis but this is subject to the numerous other factors involved.
These include the difficulty of the installation (ie. is there a false floor or ceiling or will it all have to be
trunked out!), and the type of cable and connectors that have been specified (some systems are more
expensive than others).
I think the overriding factor is usually down to the
amount of man/hours involved, once a price has
been worked out for this and the material costs and
profit have been added, the total can then be divided
by the number of outlets to give a price per drop.
The same goes for a fibre installation although the
cost of materials is higher than copper.
The going rate? well, I live in the UK and the price
per point can vary from £25 (approx. $50) to £100
(approx. $200) depending on the building and, of
course, the amount of outlets involved.
General Cabling Questions