Cable Colors - A Standard
gdt at gdt.id.au
Thu Jun 19 11:19:33 CDT 2008
George Imburgia wrote:
> There's a standard;
> ANSI/TIA/EIA 606A
Here in Australia there's no standard for colours of data communications
But there are some non-data communications standards for fixed
cable colours. In particular, fire system sensors must use red;
the use of cream is reserved for telephony; and fixed electrical
cables must be white.
To minimise error I avoid those colours for patch cables
(ie, non-fixed cables). This is prudent anyway, as under the
Wiring Rules simply tying down a patch lead with a cable tie
is enough to turn it into a fixed cable.
I've found that it's more important to have a ready supply of
cable lengths (say 0.5m increments) and labels than to have
colours. That avoids a mess developing in the first place that
might need colour coding to sort out. We use blue, simply
because it's the most readily available colour.
The only cable which really needs a special colour is one
which doesn't connect all eight pins in sequence.
To avoid stocking many lengths of cross-over cables, we use
a 0.6m crossover cable and a Cat6 joiner. We colour these
pink -- it's noticeable and Real Men sysadmins don't steal them.
A useful tool is a audio cable tracer. When disconnecting
a PC you attach the signal injector. You then use the other
half of the tool to identify the cable (it buzzes when near).
This allows the patch cables to be pulled with certainty
rather than left in the rack just in case it attached to some
other host and you fear causing an unplanned outage.
Also I've found that many cabling messes occur because the
installer had no alternative. There was simply no cableway
that wasn't congested. For high-density routers I've found
that about 1/3rd of the rack is given over to cable patch
panels and ring runs. About two racks in ten (ie, one optical,
one UTP) need to be given over to just inter-rack patching
and I'd encourage a specialist-built patch rack for that purpose.
A rack full of PCs requires about 0.8m of available tray down the
side of the rack to tie down the patch leads and other cables.
Again, that huge amount of tray isn't usually provided, can't
be added afterwards, and the installer has no choice but to do
poor work if there's nothing to tie cables to.
We ban non-fixed cabling between our racks, which means that
patch cables only run within a rack. This simplifies things
considerably. Fortunately, we've got the fiber density to
racks to justify that design. I've noticed a considerable
fall in the price of pre-assembled optical patch panels,
so it's well worth looking at the prices even at low densities
of cables to see if they fallen enough to make a fixed
cabling system worthwhile. It's not like alternative -- those
gutters used to pull optical patch leads between racks -- are
cheap so I've expect the prices to cross at some stage in the
next few years.
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