October/November/December 2019 I 37
Compounding this situation are those LAN cables
that are connected between buildings due to a phenom-
enon known as ground potential rise (GPR). Since the
grounds at each building have a different resistance, an
elevated potential can exist on a wireline circuit running
between the buildings. This effect is increased when the
big black clouds start moving. Even without additional
electrical disturbances, such as lightning, the GPR can
be at a significant enough level to cause strange circuit
malfunctions and even damage the sensitive electronic
components and equipment in the network.
FIGURE 4: Cat 5e unshielded twisted-pair (UTP) cable.
1
IS TWISTED PAIR THE SOLUTION
TO THE EMI PROBLEM?
Twisted-pair cabling is a type of wiring in which two
conductors of a single circuit are twisted together for
the purposes of improving electromagnetic compatibility.
Compared to a single conductor or an untwisted balanced
pair, a twisted pair reduces electromagnetic radiation,
crosstalk between neighboring pairs and improves
rejection of external EMI. It was invented by Alexander
Graham Bell. Mr. Bell's discovery in 1881 helped to
minimize the effects of crosstalk interference. Prior to
LEADING OPTICAL
INNOVATIONS
LaserWave OM3, OM4 and OM5
Multimode Fibers for Today's and Tomorrow's
High-speed Networks
SPEAK WITH THE EXPERTS! BICSI Fall 2019 | Booth #1217
