STW Self-Regulating Heating Cable - Proheat

© 1997 Wiegand Industrial Division, Emerson Electric Co.
STW Self-Regulating Heating Cable
IMPORTANT SAFETY INSTRUCTIONS
When installing your cable, basic safety precautions should
always be observed, including the following:
1. Read and understand all instructions before starting.
2. Plug the pipe heating cable directly to a GFCI grounded outlet
or GFCI protected branch circuit.
3. Disconnect the pipe heating cable from its power source before
routine inspections, servicing and when the freezing season
ends.
4. Installation must be in accordance with all national, state and
local codes by a qualified person.
SAVE THESE INSTRUCTIONS
WARNING: Incorrect usage and/or improper installation
of self-regulating pipe heating cable can
cause danger of fire, electric shock, electrocution
and/or freezing of the protected pipe.
GENERAL
CAUTION: This pipe heating cable is only for the
specific uses and locations stated below. It is not
intended for, nor is it capable of, thawing frozen
water pipes. This cable will not keep a pipe from
freezing unless properly insulated (See insulation
instructions). When properly installed, this cable
will protect a pipe at -50 o F (-46 o C) air temperature.
Use Chromalox cable STW3-1C only with
Chromalox STW connector kits or approved termination
accessories.

• The cable should be installed only on residential or mobile home
water supply pipes that are rigid and located above ground. Use
only on Steel, Copper, ABS, PVC, CPVC or polybutylene pipe
rated for at least 140 o F (60 o C) service. Do not use on pipes filled
with fluids other than water. Do not use on fuel lines. Do not use
on non-rigid pipe that is not properly supported as required by
local and national plumbing codes. Do not use on flexible tubing
or garden hose.
• The cable should only be installed in sheltered, accessible locations
such as under a skirted mobile home, a crawlspace, a basement,
an attic or a domestic garage. The cable should not pass
thru a wall, floor or roof of a building or be enclosed in joist or
stud spaces. The cable should not be directly exposed to the
weather or where it can get wet.
• Never expose the cable and connectors to temperatures above
140 o F (60 o C). This would shorten the operating life of the cable.
• Maximum length of cable is 50 feet (15 meters) when power
is supplied by Chromalox PLEC-1 Plug Kit.
• Use only metal pipe hangers to suspend the pipe at least 2” (5 cm)
away from flammable materials or surfaces. See Figure 1.
Figure 1
• Do not use pipe heating cable for any other non-pipe heating
application such as roof and gutter deicing. The cable is not
designed for such applications.
• Use only fiberglass pipe insulation. Foam types of preformed
insulation must not be used as it may cause overheating, failure
of the cable and a hazardous condition.
• Protect the circuit by plugging the cable into a GFCI ground
fault device or GFCI protected branch circuit..
• Only cut the cable ends when attaching the connection plug and
the end seal. Do not attempt to splice the cable.
• Inspect the cable at the beginning of every freezing season and
every 3 months during the freezing season.
• Disconnect the power before inspecting.
• Without removing the insulation, feel the assembly to be sure it
is still secure. If the cable is loose, remove vapor seal and insulation
and reinstall cable.
• Remove small sections of the vapor seal and check if the insulation
is still dry. If the insulation is damp or wet, it must be replaced.
• Any indication of changes or problems should be checked
thoroughly.
PRE-INSTALLATION
MAINTENANCE
• Do not cut, nick or allow the jacket of the cable to be worn
down. The wire braid must remain intact.
• Before beginning installation, determine the length of the cable
you will need. To calculate the approximate length of cable needed,
first multiply the length of the pipe by the required cable length
per foot of pipe given in the Table 1. Next add 1 foot (30 cm) of
cable for each valve in the line and finally, add sufficient length to
reach from the power receptacle to the pipe.
Table 1
Metal Pipe
Pipe Size
Minimum Ambient Temperature ( oF) (In.) 0 -20 -40 -50
1/2
3/4
1
1.0 1.1 1.4 1.6
Straight 6” 2-1/2” 2”
1.0 1.3 1.7 1.9
Straight 4” 2-1/4” 2”
1.0 1.5 2.0 2.3
Straight 3-1/2” 2-1/2” 2”
Pipe Size
Minimum Ambient Temperature ( o Plastic Pipe
Feet of Cable per Foot of Pipe
Inches Between Turns
F)
(In.) 0 -20 -40 -50
1/2
3/4
1
Feet of Cable per Foot of Pipe
Inches Between Turns
1.0 1.5 N/R N/R
Straight 2-1/4” N/R N/R
1.2 1.8 N/R N/R
5” 2-1/4” N/R N/R
1.4 2.1 N/R N/R
4-1/4” 2-1/2” N/R N/R
N/R = Not Recommended
Note: Values calculated based on using 1/2” thick fiberglass insulation.
• If there are no problems, close the vapor seal and reconnect the
power cord.
• The cable, plug and end seal are NOT serviceable and, if damaged,
must all be replaced as a system.
• Disconnect the cable when the freezing season ends. Reconnect
before the next freezing season begins.
• Look for damage caused by physical abuse, accidental contact or
chewing by animals.

WARNING: Never perform any part of the installation
while the plug is connected to a power source.
CONNECTING THE PLUG TO CABLE
1. If you have not already done so, cut off just enough of one end
of the cable to provide a clean square end.
2. Pull approximately 1-1/4 to 1-1/2” of braid away from the
cable and twist it into a “pigtail.” See Figure 2.
Figure 2
3. Strip off approximately 1-1/4” of the blue outer jacket. See
Figure 3.
Figure 3
4. Using a sharp knife, split the black inner core of cable into 2
parts. See Figure 4.
Figure 4
5. Strip off the black core from each of the two cable bus wires
for a length of approximately 1/2”. See Figure 5.
Figure 5
INSTALLATION
6. Remove the 2 cover screws in the plug and open the covers.
See Figure 6.
Figure 6
7. Loosen, but do not remove, the 3 terminal screws inside the
plug. See Figure 6.
8. Insert one of the cable bus wires in the terminal marked
BLACK and tighten the terminal screw. See Figure 6.
9. Insert the second cable bus wire in the terminal marked
WHITE and tighten the terminal screw. See Figure 6.
10. Insert the cable braid pigtail into the terminal marked GREEN
and tighten the terminal screw. See Figure 6.
11. Close the plug covers. Insert and tighten the two (2) cover
screws. See Figure 6.
12. Attach the orange WARNING label around the cable next to
the connector plug. See Figure 7.
Figure 7
CAUTION: Before installing the new cable, remove
all old heating cables and insulation. Remove all
burrs and sharp edges from the pipe.
INSTALLING CABLE ON A WATER PIPE
1. See Figure 8. Using glass cloth or polyester tape, attach the
plug end of the cable to the pipe allowing only enough of the
cable to hang free to reach the electrical receptacle to be used
to power the cable. Do not allow excess cable to hang in a
loose loop.
2. Wrap the cable around the pipe using the distance between
turns recommended in Table 1. Use glass cloth or polyester
tape every six inches (6”) (15 cm) to hold the cable snug
against the pipe.
3. At the far end of the pipe, decide where you will be placing the
end cap and cut the cable to provide a clean, square end.
Figure 8

CONNECTING THE END CAP
1. Remove the cover screw and the cap cover. See Figure 9.
2. Slide the wire braid back about one inch (1”) (2.5 cm) from the
end of the cable and hold in place with glass cloth or polyester
tape. See Figure 9.
3. Push the bared end of the cable into the back end of the tunnel
until it stops, about one-half inch (1/2”) (1.2 cm).
4. Tighten the two (2) contact screws until they are snug against
the ring terminals of the pilot light assembly. Be sure the pilot
light and its lead wires are positioned so they will not be
pinched when the cover is replaced.
Figure 9
5. Replace the cap cover and insert and tighten the cover screw.
6. Position the end cap so that the cable enters the bottom of the
cap and pilot light will be visible and use glass cloth or polyester
tape to hold it in place. Do not cover the “lighted area” as
shown in Figure 10 with tape. The pilot light will glow whenever
the cable is connected to an energized power source and
indicates that the system is operating. Never install the cable
end cap in a mobile home crock or standpipe where it can get
wet. See Figure 10.
Chromalox warrants only that the Products and parts manufactured by Chromalox, when shipped, and
the work performed by Chromalox when performed, will meet all applicable specification and other specific
product and work requirements (including those of performance), if any, and will be free from defects in
material and workmanship under normal conditions of use. All claims for defective or nonconforming (both
hereinafter called defective) Products, parts or work under this warranty must be made in writing immediately
upon discovery, and in any event, within one (1) year from delivery, provided, however all claims for
defective Products and parts must be made in writing no later than eighteen (18) months after shipment by
Chromalox. Defective and nonconforming items must be held for Chromalox’s inspections and returned to
the original f.o.b. point upon request. THE FOREGOING IS EXPRESSLY IN LIEU OF ALL OTHER WAR-
RANTIES WHATSOEVER, EXPRESS, IMPLIED AND STATUTORY, INCLUDING, WITHOUT LIMITATION, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
Notwithstanding the provisions of this WARRANTY AND LIMITATION Clause, it is specifically understood
that Products and parts not manufactured and work not performed by Chromalox are warranted only to the
extent and in the manner that the same are warranted to Chromalox by Chromalox’s vendors, and then only
to the extent that Chromalox is reasonably able to enforce such warranty, it being understood Chromalox
shall have no obligation to initiate litigation unless Buyer undertakes to pay all cost and expenses therefor,
including but not limited to attorney’s fees, and indemnifies Chromalox against any liability to Chromalox’s
WARRANTY AND LIMITATION OF REMEDY AND LIABILITY
600 RIDGELY ROAD, MURFREESBORO, TN 37129
PHONE: (615) 848-2565 FAX: (615) 848-2181
INSTALLATION
Insulation is required over the cable to help prevent pipe freezing
and to protect the cable.
Figure 10
INSULATING THE CABLE
1. See Figure 11. Use only one-half inch (1/2”) (1.2 cm) thick
fiberglass insulation that is clean and dry.
2. Cover the cable, pipe, valves, etc. with one (1) thickness of the
insulation. Do not insulate the cable section between the pipe
and the attachment plug.
3. To protect from moisture, wrap plastic vapor seal over the
insulation overlapping turns by 1/4 to 1/2” (0.6 to 1.2 cm). On
vertical pipes, wrap from the bottom to the top so water drops
will run off without leaking into insulation. Use glass cloth or
polyester tape to hold the vapor seal in place. Vapor seal will
not protect from direct exposure to the weather or from physical
damage. Additional protection should be provided if necessary.
Figure 11
vendors arising out of such litigation.
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option either (i) repair or replace its Products, parts or work at the original f.o.b. point of delivery or (ii)
refund an equitable portion of the purchase price.
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ARISING HEREUNDER OR RELATING HERETO WHETHER SUCH CLAIMS ARE BASED ON BREACH OF
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RELATING HERETO, WHETHER BASED ON BREACH OF CONTRACT, TORT (INCLUDING NEGLIGENCE AND
STRICT LIABILITY) OR OTHER THEORIES, MUST BE COMMENCED WITHIN ONE (1) YEAR AFTER THE
DATE OF SHIPMENT OR IT SHALL BE BARRED.
W2008M
98-002
TA - Y7 - 3K
Litho in U.S.A.