For UTP Cabling
a simple test that confirms that each wire is hooked
up correctly, with no opens or shorts. UTP intended only
for POTS (plain old telephone service) voice applications
actually only needs to be tested for wiremap. Wiremapping
is very straightforward. Structured cabling standards do
not consider simple voice grade cable, only cable of
Category 3 or above, so most cable testing will require
more than just wiremapping, either certification or
verification, so wiremap testing is done in the tester
before other tests. Each pair must be connected to the
correct pins at the plugs and jacks, with good contacts in
the terminations. A "wiremapper" is basically a continuity
checker that determines if pins are correctly connected.
of the failures are simple enough to understand, like
reversed wires in a pair, crossed pairs, opens or shorts.
One possible failure, crossed pairs, is caused when both
wires of a pair are crossed at one termination. The usual
cause of a crossed pair is a 568A termination on one end
and a 568B on the other.
most difficult wiremap problem is a split pair, when one
wire on each pair is reversed on both ends. It causes the
signal to be sent on one wire each of two pairs. The usual
DC wiremap will pass but crosstalk will fail. It takes a
more sophisticated wiremapper or Cat 5e/6/6a tester to
find a split pair, as some wiremappers which use only DC
tests do not check crosstalk. In our experience, a split
pair is usually caused by someone using punchdown color
codes on jacks which splits the pairs.
Here are examples of wiremap faults. Compare the diagrams to
the correct one above to see the wiring errors.
here, pair 2 (orange) is open because tip is not connected.
Pair 3 (greeen) is shorted on pin 6.
(green) has tip and ring reversed.
(orange) and pair 3 (green) are crossed, connected to
each others pins. The usual cause of crossed pairs is
one end is terminated at T568B and the other end T568A, where
pairs 2 and 3 are reversed.
or Crossed Pairs
pairs are when one wire of each pair is improperly connected.
Here pairs 1 (blue) and 3 (green) are connected such that a DC
wiremap tester will test OK, but the signals are being carried
on one wire of two pairs, so the cables are unbalanced. Split
pairs are often caused by the wires being punched down on a
jack using the color codes for punchdown blocks.
your comprehension with the section quiz.
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