9
Installation Guide: Multiple Cable Runs
There are two cases where you will need to install more than
one heater cable on a pipe:
• When the design calls for more than one cable.
• When the lines being heat traced are considered impor-
tant enough to install a backup (redundant) heat tracing
system.
The installation requirements are different for these cases.
Installing Multiple Heater Cables for
Design Requirement
The most common multiple cable requirement is two cables
on a pipe. Below are the recommended techniques for the
two cable systems. They also apply to installations where
three or more cables are to be installed on a pipe.
There are two ways of paying out two heater cables along
a pipe. The first is to locate two reels of heater cable and
supply one cable from each. This method works for all types
of piping runs. However, it may increase material waste by
leaving unusable lengths from two reels. The second way is
to supply both cables from one reel. This method is gener-
ally the easiest for relatively straight, simple piping runs. For
each circuit, decide which method to use and then go to the
appropriate part below.
1. Supplying cable from two reels
The general procedure here is the same as given earlier,
but there are a few things to do to make sure the system
is correctly done.
a. At each heat sink, the easiest thing to do is supply the
extra heater called for by the design drawing from only
one heater cable. This avoids having to measure out
half of the requirement from each cable.
b. When doing the previous step, leave a small loop in
the other cable at equipment which may be serviced,
such as pumps, valves, instruments, etc. This is so
both heater cables may be removed enough for future
access.
2. Supplying cable from one reel
The general procedure is the same as given earlier, but
there are a few things to do to make sure the system is
correctly done.
a. With this method, a loop is pulled for the entire circuit.
To do this, attach the end of the heater cable to the
pipe near the heater cable reel. Remember to leave
enough extra cable for the type of connection to be
installed.
b. Begin pulling the cable off the reel in a large loop down
the piping run. Be sure to keep the cable next to the
pipe. Moving down the run, continue attaching the ca-
ble to the pipe, leaving the side of the loop going back
to the reel unattached.
c. You will want both sides of the loop to be about the
same length to avoid future problems. Also, it is easier
to install the extra cable required at each heat sink
from only one cable. Therefore, pull the right amount
of extra heater cable needed at every second heat
sink from the side of the loop you are attaching to the
pipe. At the remaining serviceable heat sinks (pumps,
valves, instruments, etc.) do not forget to leave a short
loop of cable for slack when access to the equipment
is needed.
d. When the end of the piping run is reached, pull the
proper amount of extra cable for the connection to be
installed.
e. Now, begin working the remaining side of the loop
back toward the reel, installing it on the pipe and heat
sinks as required.
Installing Backup (Redundant)
Systems
The purpose of a backup system is to provide the proper
amount of heat from the second heater cable if there are
problems with the first. Therefore, each cable must be in-
stalled so it can do the job alone. The simplest way to do this
is to install the first heater cable as described in the Installa-
tion Guide: Single Run of Cable section. Then, go back and
install the backup heater cable the same way.
There are several things to keep in mind:
• The power connections and end seals for the two cables
are often designed to be at opposite ends of the run in a
redundant system. Remember to leave the proper amount
of extra cable for the connection to be installed on each
cable at that end.
• On piping one inch IPS or smaller, it can be difficult to
apply both heater cables with good contact at all places.
The main thing is to get the correct amount of cable in-
stalled. However, try to get as much contact with the pip-
ing and heat sinks from both cables as possible.
