Precautions for the installation and routing of control cables:
1. Under eaves. Standard LAN cables can be used provided they are not directly exposed to sunlight or extreme heat; the use of conduits is recommended. Ultraviolet (UV) radiation-do not use cables without UV protection in environments exposed to direct sunlight.
2. On exterior walls. Avoid direct sunlight on the wall surface and prevent man-made damage. Heat-temperatures inside metal conduits or cable trays can become very high, and many polymeric materials will have a reduced service life at such temperatures.
3. Inside conduits (plastic or metal). When using conduits, be mindful of potential damage to plastic conduits and the heat conduction of metal conduits. Mechanical damage (repair costs)-fiber optic cable repair is extremely expensive, requiring at least two terminations at each break point.
4. Aerial applications/overhead cables. Consider cable sag and tension. Determine whether the cable will be exposed to direct sunlight.
5. Direct burial in underground cable trenches; this environment offers the least control. Installations in cable trenches require periodic checks for moisture levels (dryness vs. dampness). Grounding-if the control cable's shielding requires grounding, relevant standards must be followed.
6. Underground conduits. Installing conduits is a good approach to facilitate future upgrades and cable replacement, as well as to isolate cables from surface pressure and the surrounding environment. However, do not assume the conduits will remain permanently dry; this factor influences the choice of cable type. Water-moisture in LAN twisted-pair cables increases capacitance, thereby lowering impedance and causing near-end crosstalk issues.
