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6. Check the sensing cable condition.
Important: TT5000 sensing cable is sensitive to pressure from
such things as pinches or tight corners. After pulling, make sure the
cable has adequate clearance and is not left under tension.
For TT3000 sensing cable, use the ohmmeter on the payoff reel to
confirm that the cable is clean and dry. If the ohmmeter measures
a resistance of less than 20 MΩ between the sensing wires,
corrective action will be required.
If TT5000 sensing cable has been installed, first prepare the cable
for testing.
• Remove the Kellems grip, and then cut off and discard the
section of cable that was in the Kellems grip.
• Slit and remove 3/4 in (19 mm) of outer braid and black jacket.
• Unbraid the two black wires, and strip 1/2 in (12 mm) of the black
material to expose their copper wire.
• Slit an additional 1/2 in (12 mm) of outer braid and black jacket.
Flare the jacket so that it does not touch either black wire (see
illustration).
Use an ohmmeter to check that the cable has not been damaged or
left in an alarm condition.
• Measure the resistance between each black wire and the black
(conductive) jacket.
• Measure the resistance between the two black wires.
In all cases the resistance should be greater than 20 MΩ. If the
measured resistance is less than 20 MΩ:
• Confirm that the black wires at either end of the cable are not
touching the black jacket. If they touch the jacket, move them
away from the jacket and retest.
• Confirm that the cable is not pinched by the reel flange or other
object. If the cable is pinched, correct the problem and retest.
• If the measured resistance is still below 20 MΩ, it may indicate
the cable is bent or crimped (which simulates a leak), or the cable
has been tripped by exposure to a hydrocarbon (such as oil or
adhesive), or the jacket has been damaged and allowed water to
enter the braided inner construction. A TraceTek Portable Test
Box (TT-PTB-1000) may be used to determine the location of the
problem; contact your RAYCHEM representative for further
information. In any case, determine the cause of the problem and
address it.
7. Complete the installation process.
If the results of the cable test are satisfactory and the sensing
cable will be left in the pipe:
• Remove the conduit sections used to guide the cable during
installation. Before cutting the cable at the feeder end, make
sure that at least 12 in (300 mm) of sensing cable (not including
the Kellems grip) is above each riser to allow for connector
installation.
• Cut off and discard the section of cable that was in the Kellems
grip. (Note: For TT5000 cable, this should have been done in the
previous step, when preparing for cable testing).
• If possible, install connectors on ends of sensing cable
immediately after pulling, following instructions supplied with the
connector kits.
Important: Water must not be permitted to enter the end of
TT5000 cable. If not installing connectors on TT5000 cable, be
sure to seal the end with heat-shrinkable tubing, as described in
Step 1 on page 2.
• For connectors not mated to another sensing cable, attach an
end termination to prevent water ingress.
• Secure the end of cable so it is not lost into the pipe.
At the end of the day or if the job is interrupted by bad weather, seal
all access points to keep moisture and contaminants out of the pipe.
Do not let the jacket
touch the black wires
TT5000
sensing cable
To Ohmmeter
Seal access points
Secure end of cable
nVent.com | 5
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