Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide - Manual (Page 52)

52 Rockwell Automation Publication CNET-IN001C-EN-P - October 2011
Chapter 3 Guidelines for Fiber-optic Installation
Vertical Installation
The requirements of your application may require a vertical installation. You can
install fiber-optic cable vertically in trays, shafts, or towers. Dielectric cables are
recommended for applications requiring high vertical installations, radio towers
for example.
Use the following guidelines when planning a vertical cable installation.
1. Clamp cable to give extra support in preventing ice loading and wind
slapping.
Your specific environment will determine where you should clamp your
cable. Clamping intervals can be as short as 1 m (3 ft) and as long as
15…30 m (50…100 ft) in interior locations.
Cables in vertical cable shafts are generally clamped directly to the walls of
the shaft.
Cables installed in elevator shafts are usually supported by suspension
strands and suspended from the top of the shaft. The suspension strand is
attached to the wall at frequent intervals and at the bottom of the shaft.
Consult your local codes and practices for installation in an elevator shaft.
2. Avoid downward migration of cable in loose-tube constructions by looping
the cable approximately 0.3 m (1 ft) in diameter at the top, bottom, and
every 150 m (500 ft).
In loose-tube constructions cable may migrate downward creating
crowding at the bottom. The crowding may cause an increase in
attenuation, especially in below freezing temperatures.
3. Plan cable runs that keep bends to a minimum.
4. Drill all holes for the entire run larger enough to accommodate steel sleeves
when passing cables through walls and floors.
The inside diameter of steel sleeves should be 4 times the diameter of the
cable. The minimum diameter of a steel sleeve is 5 cm (2 in.).
Steel sleeves are required to run cable through a firewall. Consult your
local codes and practices for installations through firewalls.
5. Measure and record the optical cable attenuation and length by using
either an OTDR (optical time domain reflectometer) or an optical test.
6. Seal the ends of the cable with endcaps until they are terminated.