Information Technology Reference
In-Depth Information
TABLE A.2
Common Types of Coaxial Cable
Typical Center
Nom.
Nom.
Coaxial
NEC
cond.
imped.,
vel. prop.
Typical O.D.
cable type
Rated use
type
AWG
ohms
(c), %
mm
in
RG-6/U
Nonplenum
CL2
8 sol.
75
82
6.86
0.270
Plenum
CMP
18 sol.
75
82
5.94
0.234
RG-8/U
Nonplenum
CL2
11 str.
50
78
10.24
0.403
Plenum
CMP
10 str.
50
83
9.07
0.357
RG-11/U
Nonplenum
CM
14 sol.
75
78
10.29
0.405
18 str.
75
66
10.29
0.405
Plenum
CMP
14 sol.
75
83
8.84
0.348
FG-58/U
Nonplenum
CL2X
20 sol.
50
66
4.90
0.193
Plenum
CMP
20 sol.
53.5
69.5
4.04
0.159
RG-58A/U
Nonplenum
CL2
20 str.
50
66
4.90
0.193
Plenum
CL2P
20 str.
50
80
4.06
0.160
RG-59/U
Nonplenum
CM
20 sol.
75
78
6.15
0.242
Plenum
CMP
20 sol.
75
82
5.38
0.212
RG-62/U
Nonplenum
CM, CL2 22 sol.
93
84
6.15
0.240
Plenum
CMP
22 sol.
93
85
5.08
0.200
Ethernet
10Base2
Nonplenum
CL2
20 str.
50
80
4.70
0.185
Plenum
CL2P
20 str.
50
80
4.06
0.160
Ethernet
10Base5 Nonplenum CM, CL2 12 sol. 50 78 10.29 0.405
Plenum CMP 12 sol. 50 78 9.53 0.375
NOTE: In general, a cable with a more strict usage code may be substituted in an application that allows a less
strict usage code. For example, a cable rated to the stricter Class 2, Plenum (CL2P) code may be substituted in a
Class 2, Riser (CL2R) application. Likewise, CMP, MPP, and FPLP, which may be substituted for CL3P, will substi-
tute for any code that allows CL3P to be substituted. The chart does not list all possible substitutions, only those
to the next level.
The shielding properties of the cable depend somewhat upon good ground con-
nections (both signal and earth grounds). However, the interconnection of grounds
from different parts of a building, or even between buildings, can cause problems.
Grounding requirements for thick Ethernet coax are fairly severe, to ensure proper
operation. Safety and signal integrity are also issues in grounding. The NEC and
EIA/TIA-607 detail grounding and bonding requirements for coax LAN cable.
Coax consists of a center conductor and a coaxially positioned outer shield
conductor separated by an insulating material, called a dielectric .
Ethernet LAN wiring uses two types of coax cable, often referred to as thick-
net and thinnet . Thicknet is the original Ethernet coax trunk distribution cable, now
 
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