14
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Reference
XX028-06-00 Rev 1002 Surveyor4 Fixed-Position Camera Dome
Twisted-Pair Cable
Caution:
Careful selection of the proper cable is essential to obtain the best performance from this
equipment. Vicon assumes no responsibility for poor performance when cables other than those
recommended are installed.
Materials
Use a pure copper stranded or solid conductor with or without a tin plating to obtain a low DC resistance. Do not use
cable with either steel or aluminum stranded conductor because these do not transfer signals effecti vely for long
distances. The preferred insulation is Polyvinyl chloride (PVC). It has better electrical characteristics than polyethylene
and resists flames, sunlight and most solvents, but is more vulnerable to moisture.
Cable Types
The most commonly us ed cable types are point-to-point unshielded twisted pair wire, stranded or solid, unjacketed,
24 gauge or thicker. They can be category 2, 3, 4, or 5. The video signal may co-exist in the same wire bundle as other
video, telephone, data, control signals or low-voltage power. It is also acceptable to run the signal adjacent to
fluorescent lights or other power sources (in accordance with National Electrical Code, local and other safety
requirements). Make sure the pair of wires carrying the video signal is sent as a twisted pair (the blue-white/white-blue
wires twisted together as a pair), not a “split pair” (blue-white conductor, part of one pair/orange-white conductor, part of
another pair).
Choose a Belden or equivalent cable type by referring to the characteristics and maximum distances listed below. The
characteristics of the cables in the Tables should be used as a guideline when cables other than Belden are used.
Materials and construction must follow the guidelines above.
Wire resistance may be measured with an ohmmeter by shorting the two conductors together at the far end and
measuring the loop-resistance out and back. Compare your readings to the following chart.
Wire Distances
Wire Gauge AWG
Distance ft (m)
18
20
22
24
250 (76)
3
Ω
5
Ω
8
Ω
13
Ω
315 (96)
4
Ω
6
Ω
10
Ω
16
Ω
397 (121)
5
Ω
8
Ω
13
Ω
21
Ω
500 (152)
7
Ω
10
Ω
17
Ω
26
Ω
630 (192)
8
Ω
13
Ω
21
Ω
33
Ω
794 (242)
10
Ω
16
Ω
26
Ω
41
Ω
1000 (305)
13
Ω
20
Ω
33
Ω
52
Ω
1260 (384)
16
Ω
25
Ω
42
Ω
66
Ω
1587 (484)
21
Ω
32
Ω
52
Ω
83
Ω
2000 (610)
26
Ω
40
Ω
66
Ω
104
Ω
Note: All quoted distance specifications include any coaxial cable in the run. It is recommended that the wire distance
be measured to ensure that the capability of the product is correct.
Recommended Unshielded Twisted-Pair Cable Type
Cable Type
Wire Size
(AWG)
Insulation Material Conductor Type
Resistance (ohms)
Number of
Twisted Pairs
Belden1721X
24, Solid
Polyethylene
Bare Copper
100
1
