CommScope ConQuest Conduit Construction - Manual (Page 18)

3.5 General Conduit Installation Practices
Mechanical Stress
Mechanical Stress
Regardless of the installation method, mechanical stress is of great concern during conduit and cable placement.
Exceeding the maximum allowable pulling tension can damage conduit and cable. Pulling tensions for ConQuest
conduits can be found in specifications at the end of this manual.
Pulling Tension
There are three general causes that effect pulling tension during the installation of conduit or cable: conduit or cable
weight, sidewall pressure, and tail loading.
Weight of the conduit or cable can be directly associated to pulling tension as a factor of force required to move
and object weighing a number of pounds over a given distance. The more the conduit or cable weighs, the greater
the pulling tension. The longer the distance, the greater the pulling tension.
Sidewall Pressure or loading is the radial force exerted on a conduit or cable when pulled around a bend or
sheave. Excessive sidewall pressure can crush the conduit or the cable.
Tail Loading is the tension on the conduit or cable caused by the mass of the conduit on the reel and reel brakes.
Tail loading is controlled by two methods. It can be reduced using minimal braking during the pay-off of the conduit
from the reel – at times, no braking is preferred. Rotating the reel in the direction of pay-off can also minimize tail
loading.
WARNING: Exceeding maximum pulling tension can result in the conduit drawing down in
size, while it may recover after a period of resting, the mechanical properties of the conduit
are permanently degraded which may reduce the life expectancy of the conduit. Exceeding
maximum pulling tension of cables can damage the electrical or optical performance.
Break-away swivels should be placed on the conduit to ensure that the maximum allowable tension for that specific
conduit or cable type is not exceeded. The swivel is placed between the conduit/cable pull member and pulling grip.
A break-away swivel is required for each conduit or cable.