Design Guide and

Installation Details
for Self-Regulating
Heating Cable
 Design Guide and Installation
Self-Regulating Details for Self-Regulating
Heating Cables Heating Cable

The RSCC 2700 self-regulating heat- Accesories

ing cable is available with either a Conductors Conductors 1548-40PTP
tinned copper or stainless steel over- Electrical Connection Kit
shield. Factory Mutual approved for 1548-40PTJ
Self-regulating Self-regulating Electrical Connection Kit
use in Class I, Division 2, Groups B, conductive conductive with Junction Box
C, and D; Class II, Division 2, Group core core
SRHC-ES
G; Class III, Division 2 areas. It is End Seal Kit
Fluoropolymer Thermoplastic
rated for T5 per NEC. Meets or jacket elastomer 1528-01019
exceeds requirements of IEEE Electrical jacket Fiberglass Adhesive Tape
Resistance Heat Tracing .5" x 108'. 185°C
Metallic Metallic
Specifications. The RSCC 2300 self- overshield overshield 1528-01017
Fiberglass Adhesive Tape
regulating heating element is avail- .5" x 108'. 130°C
able with either a tinned copper or 1528-0A018
Optional
stainless steel overshield. Factory Optional fluoropolymer Aluminum Tape
2.5" x 108', 2 mil thick
Mutual approved for use in Class I, fluoropolymer or thermoplastic
jacket elastomer 1600-XXXXX
Division 2, Groups B, C, and D; outer jacket Thermostats NEMA 4X
Class II, Division 2, Group G; Class and NEMA 7 Ambient
III, Division 2 areas. It is rated for T3 Construction of 2305/10/15 Construction of 2703/05/08/10 and Line Sensing
per NEC and meets or exceeds
requirements of IEEE Electrical
Resistance Heat Tracing Specifications.

Use of Ground Fault

Protective Devices
Caution . . . N.E.C. CODE 1996
STATES IN ARTICLE 427-22: ‘Ground-
fault protection of equipment shall
be provided for each branch circuits
supplying electric heating equipment.’

Factory Mutual approvals require the use of

RSCC components and accessories

Electrical Specifications 2703-1 2703-2 2705-1 2705-2 2708-1 2708-2 2710-1 2710-2 2305-1 2305-2 2310-1 2310-2 2315-1 2315-2

Service Voltage (Volts) 120 240 120 240 120 240 120 240 120 240 120 240 120 240
Maximum Circuit Length (Feet) 330 660 270 540 210 420 180 360 240 480 180 280 135 200
Thermal Rating at 50-F (Watts/FT.) 3 3 5 5 8 8 10 10 5 5 10 10 15 15
Temperature Rating
Maximum Maintain (Deg. F) 150 150 150 150 150 150 150 150 250 250 250 250 250 250
Maximum Exposure (Deg. F) 185 185 185 185 185 185 185 185 366 366 366 366 366 366

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1
 Design Guide and Installation
Introduction Details for Self-Regulating
Heating Cable

Principle of Operation Table 1 — Thermal Conductivity (Ki) of Typical Pipe

Insulating Materials
RSCC self-regulating heating cables
regulate their heat output in response K Factor @ 50°F Mean
to changes in temperature. The highly Insulating Material Temperature (BTU/HR-FT2-°F/Ft.)
engineered conductive core increases
its heat output when the temperature Glass Fiber .021
falls and decreases its heat output Calcium Silicate .031
when the temperature rises. Foamed Urethane .014
Foamed Rubber .025
To help protect against impact and Mineral Fiber .027
mechanical abuse, these heating cables Foamed Glass .031
have a metallic overshield. These Perlite (Expanded Silicate) .040
heating cables are Factory Mutual
approved for use in hazardous areas.

This design guide was compiled to Graph 1 — Heater Power Output

offer a simplified systematic approach
for designing pipe heat tracing systems
utilizing the RSCC self-regulating heat-
ing cables.

The following step-by-step procedures

will enable you to determine the length
of heating cable required to efficiently
heat trace pipes, valves and flanges.

Alternate Voltages
RSCC 240 VAC self-regulating heating
cables can be operated at alternative
o
voltages. The chart below compares
heating cable power output with prod-
uct rating.

Power Adjustment Factor o

Part No. 208 Volts 277 Volts

2703-2 .75 1.28
2705-2 .86 1.16
2708-2 .91 1.10
2710-2 .93 1.08
2305-2 .78 1.25
2310-2 .86 1.16
2315-2 .92 1.09

Example:
Thermal output of 2705-2 5 Watts/Ft.
at 50°F, powered at 208 VAC = 5
Watts/Ft. x .86 = 4.3 Watts/Ft.

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 Heat Tracing Pipe

To determine the pitch and amount of In some circumstances it may be desired Determine Heater Pitch
RSCC self-regulating heating cable to use a heater with less power output To determine the required pitch (P),
required to heat trace a pipe, you’ll per foot of heater than the calculated select value from Tables 3A and 3B for
need to know the pipe temperature to heat loss per foot of pipe. In these calculated value of (Rp) and pipe size.
be maintained, minimum ambient tem- cases, the heater can be spiralled
perature, pipe size and insulation type onto the pipe to achieve the required
Calculate Required
and thickness. power output per foot of pipe. A
Heater Length
developed power ration and heater
To determine required heater length
Calculating Heat Loss pitch will need to be determined.
(Lh), multiply length of pipe (Lp) by (Rp).
1. First determine temperature differ- Lh = Lp x Rp.
ence (⌬T) between temperature to Calculate Developed
be maintained (Tm) and minimum Power Ratio
ambient temperature (Ta). To calculate developed power ratio
⌬T = Tm - Ta. (Rp) divide heat loss from pipe (Qp)
2. Select insulation K factor from by heater power output (Qh).
Table 1 (Ki) and divide by .021 to Rp = Qp ÷ Qh.
determine conductivity ratio (Rk).
Rk = Ki ÷ .021. Table 2A — Heat Loss (Qa) from Insulated Pipe (Watts/Foot-°F).
3. Determine heat loss from Table 2A Pipe Pipe
(Qa) by selecting pipe size and Insulation Thickness
Size O.D.
insulation thickness. If piping is (IPS) (Inches) 1/2" 1" 1-1/2" 2" 2-1/2" 3" 4"
indoors multiply (Qa) by 0.9. 1/2 0.840 .05 .04 .03 .03 — — —
3/4 1.050 .06 .04 .03 .03 — — —
4. Calculate heat loss from pipe (Qp)
1 1.315 .07 .05 .04 .03 .03 —
by multiplying ⌬T by Rk and Qa. 1-1/2 1.900 .09 .06 .04 .04 .03 — —
Qp = ⌬T x Rk x Qa. 2 2.375 .11 .07 .05 .04 .04 — —
2-1/2 2.875 .13 .08 .06 .05 .04 — —
3 3.500 .16 .09 .07 .05 .05 — —
Determine Heater 3-1/2 4.000 .18 .10 .07 .06 .05 .05 —
4 4.500 .20 .11 .08 .06 .06 .05 .04
Power Output 6 6.625 .28 .15 .11 .09 .07 .06 .05
From Graph I (page 3) select the heater 8 8.625 .35 .19 .13 .10 .09 .08 .06
with the power output (Qh) which meets 10 10.750 .44 .23 .16 .13 .10 .09 .07
12 12.750 .51 .27 .19 .14 .12 .10 .08
or exceeds the heat loss (Qp) from 14 14.000 .56 .29 .20 .16 .13 .11 .09
the pipe. For non-metal pipe multiply 16 16.000 .64 .33 .23 .18 .15 .12 .10
the power output Qh from the chart by 18 18.000 .71 .37 .25 .20 .16 .14 .11
20 20.000 .79 .41 .28 .21 .18 .15 .12
0.7 before selecting the heater. 24 24.000 .94 .48 .33 .25 .21 .18 .14

Values given above are heat loss for metal pipe in units of Watts/Foot of pipe per °F temperature difference from pipe to
ambient temperature fiberglass insulation.

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 Design Guide and Installation
Details for Self-Regulating
Heating Cable

Table 3A — Pitch in Inches of Heater Wrap on Pipe for Given Example: (2700 Heater)
Heat Loss/Developed Power Ratios of 1.1-2.0
Ta = -20°F
Pipe Pipe Tm = 40°F
Heat Loss/Developed Power Ratio Insulation — Calcium Silicate
Size O.D.
(IPS) (Inches) 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 Pipe Material — Metal
Insulation Thickness — 2"
1/2 0.840 6 4 3 3 3 2 2 — — —
3/4 1.050 7 5 4 4 3 3 2 2 2 2 Length of Pipe — 100'
1 1.315 9 6 5 4 4 3 3 3 2 2
1-1/4 1.660 11 8 6 5 5 4 4 3 3 3
Step I ⌬T = Tm-Ta
1-1/2 1.900 13 9 7 6 5 5 4 4 4 3 = 40 - (-20)
2 2.375 16 11 9 7 6 6 5 5 4 4 = 60
2-1/2 2.875 20 14 11 9 8 7 6 6 5 5
3 3.500 24 17 13 11 10 9 8 7 7 6 Step II Rk = K ÷ .021
3-1/2 4.000 27 19 15 13 11 10 9 8 8 7 = .031 ÷ .021
4 4.500 31 21 17 14 13 11 10 9 9 8
5 5.563 38 26 21 18 16 14 13 12 11 10 = 1.48
6 6.625 45 31 25 21 18 17 15 14 13 12 Step III Qa from Table 2A for 6 IPS
8 8.625 59 41 32 27 24 22 20 18 17 15
10 10.750 74 51 41 34 30 27 25 23 21 19 pipe and 2" thick insulation
12 12.750 87 60 48 41 36 32 30 27 25 23 is .09.
14 14.000 96 66 53 45 39 35 32 29 27 25
16 16.000 110 76 61 51 45 40 37 34 31 29 Step IV Qp = T x Rk x Qa
18 18.000 123 89 68 58 51 45 41 38 35 33 = 60 x 1.48 x .09.
20 20.000 137 95 76 64 56 50 46 42 39 36
24 24.000 164 114 91 77 67 60 55 50 47 43
= 8.0
Step V From Graph 1, at 40°F the 2708
heater produces Qi of 8.5 watts
Table 3B — Pitch in Inches of Heater Wrap on Pipe for Given per foot. Select the 2708 heater
Heat Loss/Developed Power Ratios of 2.2-4.0 for this application.

Pipe Pipe
Alternate Heater by
Heat Loss/Developed Power Ratio Spiralling
Size O.D.
(IPS) (Inches) 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 Assume that for the above example
2 2.375 4 3 3 3 3 2 2 2 2 2 you wish to use a 2705 heater.
2-1/2 2.875 5 4 4 3 3 3 3 3 2 2
3 3.500 6 5 5 4 4 3 3 3 3 3
The Qi, from Graph 1, at
3-1/2 4.000 6 6 5 5 4 3 3 3 3 2 40°F for the 2705 heater is
4 4.500 7 6 6 5 5 5 4 4 4 4 5.5 watt per foot.
5 5.563 9 8 7 7 6 6 5 5 5 4
6 6.625 11 10 9 8 7 7 6 6 6 5 Step VI Rp = Qp ÷ Qh
8 8.625 14 12 11 10 9 9 8 8 7 7 = 8.0 ÷ 5.5
10 10.750 17 15 14 13 12 11 10 10 9 8
12 12.750 20 18 17 15 14 13 12 12 11 10 = 1.46
14 14.000 22 20 18 17 15 14 13 13 12 11 Step VII The pitch, P, in inches from
16 16.000 26 23 21 19 18 16 15 14 14 13
18 18.000 29 26 23 21 20 18 17 16 15 14 Table 3A for 6 IPS and
20 20.000 32 29 26 24 22 21 19 18 17 16 Rp = 1.46 is 14 inches
24 24.000 38 35 31 29 27 25 23 22 20 19
Step VIII Lh = Lp x Rp
Heat Loss/Developed Power Ratios should be rounded to the next highest value. = 100' x 1.46
Heat Loss/Developed Power Ratios less than 1.1, run the heating cable parallel to the pipe.
= 146' cable length required.

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 Heat Tracing Valves

To determine the amount of RSCC self- Table 2B — Heat Loss (Qb) from Insulated Valves (Watts/°F)
regulating heating cable required to
heat trace a valve, you’ll need to Valve
Insulation Thickness
Size
know the pipe temperature to be main- (Inches) 1/2" 1" 1-1/2" 2" 3" 4"
tained, minimum ambient
temperature, valve size and insulation 1/2 .30 .16 .11 .09 .07 .04
3/4 .31 .16 .12 .10 .07 .05
type and thickness. 1 .35 .18 .13 .10 .08 .05
1-1/2 .44 .23 .16 .13 .10 .06
Calculating Heat Loss 2 .49 .26 .18 .14 .11 .07
2-1/2 .56 .29 .21 .16 .12 .08
1. First determine temperature difference 3 .64 .34 .24 .19 .14 .09
(⌬T) between temperature to be main- 3-1/2 .71 .37 .26 .21 .16 .10
tained (Tm) and minimum ambient 4 .77 .41 .29 .23 .17 .11
6 1.06 .56 .40 .31 .23 .16
temperature (Ta). ⌬T = Tm - Ta. 8 1.33 .71 .50 .40 .29 .19
10 1.67 .88 .62 .49 .37 .24
2. Select insulation K factor from 12 2.07 1.09 .77 .61 .46 .30
Table 1 (Ki) and divide by .021 to 14 2.32 1.23 .86 .69 .51 .34
determine conductivity ratio (Rk). 16 2.61 1.44 1.01 .80 .60 .40
Rk = Ki ÷ .021. 18 2.99 1.65 1.16 .92 .69 .46
20 3.24 1.86 1.31 1.04 .78 .51
3. Determine heat loss from Table 2B 24 3.98 2.28 1.61 1.28 .96 .63
(Qb) by selecting valve size and
insulation thickness. If valve is
Calculate Required Step II Rk = K ÷ .021
indoors multiply (Qb) by 0.9. = .031 ÷ .021
Heater Length
4. Calculate heat loss from pipe (Qv) To determine required heater length = 1.48
by multiplying ⌬T by Rk and Qb. (Lh), multiply number of valves (Nv) by Step III Qa from Table 2B for 6"
Qv = ⌬T x Rk x Qb. (Rp). Lh = Nv x Rp. valve and 2" thick insulation
is .31.
Determine Heater Step IV Qv = ⌬T x Rk x Qb
Example: (2708 Heater)
Power Output = 60 x 1.48 x .31.
Ta = -20°F
From Graph I determine heater power = 27.5
output for pipe temperature to be main- Tm = 40°F
Insulation — Calcium Silicate Step V Qh from Graph 1 for 40°F
tained (Qh). If valve is non-metal multiply required temperature is 8.5.
value of Qh from graph by 0.7. Valve Size — 6 IPS
Insulation Thickness — 2" Step VI Rp = Qv ÷ Qh
Calculate Developed Number of Valves — 2 = 27.5 ÷ 8.5
Power Ratio = 3.24 feet per heater
Step I ⌬T = Tm-Ta
valve
To calculate developed power ratio = 40 - (-20)
(Rp) divide heat loss from valve = 60 Step VII Lh = Nv x Rp
(Qv) by heater power output (Qh). = 2 x3.24
Rp = Qv ÷ Qh. = 6.5'

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5
 Design Guide and Installation
Heat Tracing Flanges Details for Self-Regulating
Heating Cable

Heater Allowances for Insulated Pipe Flanges, Fittings and Hangers

To determine the amount of RSCC self-regu- Example: for 60°F temperature Pipe flanges, fittings and hangers act as
lating heating cable required to heat trace an difference: heat sink devices in a heat trace system.
insulated pipe flange, fitting or hanger, sim- Allowances must be made for these
(2) 10" flanges (4" heater per 10 degrees
ply find the size on the verticle axis, read devices to maintain a consistent and opera-
difference); 2 x 4 x 60/10 = 48.0"
across to the appropriate device, then read tional system.
down to the horizontal axis to determine the (1) 10" fitting (4" heater per 10 degrees
amount of cable required per 10°F tempera- difference); 1 x 4 x 60/10 = 24.0" For pipe flanges and fittings under two
ture difference. Multiply the temperature dif- inches in size use four inches of heater per
(4) 7" wide hangers (4" heater per 10 degrees
ference by this value and divide by ten to device. For hangers under two inches in
difference); 4 x 4 x 60/10 = 96"
get the inches of cable to use per device. size use six inches of heater per device.
Hanger sizing is determined by the width of Total 168"
the hanger. Total Allowance Required = 14.0'

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 Design Guide and Installation
Positioning and Attachment Details for Self-Regulating
of Heating Element Heating Cable

Spiral Installation
of Heating Element

Note:
1. If ratio of heater footage to pipe
is greater than 1.5 — use two
parallel heaters or select higher
wattage heater. If ratio is less than
*Glass Tape P/N 1528-01017, 1528-01019
1.0 — use one parallel heater.
2. When installing the heater on
non-metal pipe secure the heater to
the pipe with aluminum tape. Refer
to pitch chart on isometric drawings
for proper pitch length.

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 Design Guide and Installation
Power Connection Kit Mounting Detail Details for Self-Regulating
Ordinary and Hazardous Areas Heating Cable

Connection Kits (Not supplied)

P/N 1527-26010
P/N 1548-40000 (not included in kits)
(2700 Family)
P/N 1548-41000
(2300 Family)

Note:
1. For more specific details and full
materials list refer to installation
instruction sheet packed with
connection kit

Heating Element Termination

and Heating Element Tee Splice

P/N 1535-02080
End Seal Kit
P/N 1548-50300 P/N 1548-50211

*Glass Tape P/N 1528-01017, 1528-01019

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 Design Guide and Installation
Thermostat Sensor Positioning Details for Self-Regulating
and Attachment on Tanks Heating Cable

Positioning and Attachment of

Thermostat Sensor on Pipe

*Glass Tape P/N 1528-01017, 1528-01019

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9
 Design Guide and Installation
Heat Tracing of Fittings, Details for Self-Regulating
Valves and Process Equipment Heating Cable

Note:
This detail is shown as an illustration of a
method of taking advantage of the shape of
a piping configuration to attain good pipe
contact. To simply trace the inside radius of
the corner would not be considered correct.
Although a tee-splice might also be used to
trace the third leg of the tee. The objective of
this detail is to emphasize that it is advisable
to get more heater on any area where the
thermal insulation might not be fitted as well
as on straight pipe. This method is intended
to be used on other fittings besides tees.

*Glass Tape P/N 1528-01017, 1528-01019

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 Heat Tracing of Fittings
Valves and Process Equipment

Notes:
1. Exact configuration may vary per valve type.
2. For removable valve bodies leave a loop of
tracing of the proper length when tracing the
pipe.
3. See installation chart for correct amount of
tracing per valve size.
4. Take care to keep the flat side of the heater in
as good physical contact with the valve body
as possible. *Glass Tape P/N 1528-01017, 1528-01019
5. Fully insulate and weather protect.

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 Design Guide and Installation
Details for Self-Regulating
Heating Cable
Connection Kits
P/N 1548-40000
(2700 Family)
P/N 1548-41000
(2300 Family)

Notes:
1. See National Electrical Code paragraph 427-12(E).
2. Fully insulate and weatherproof (if outdoors).
Note:
Heater must be pulled thru flexible conduit to avoid splicing —
if necessary to splice heater a junction box will be required.

Note:
Use fiberglass or aluminum tape to hold tracer in place on pump body.
Note:
Fully insulate and weather protect.

*Glass Tape P/N 1528-01017, 1528-01019

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 Heat Tracing Around
Pipe Supports

Note:
All forms of rigid pipe supports directly
in contact with the pipe surface act
as a heat sink. Heat tracing should be
doubled over at these points and the
supports should be insulated as much
as practicable to limit heat loss.

Note:
Insulate as much of shoe support as
possible and weather protect all openings.

*Glass Tape P/N 1528-01017, 1528-01019

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13
 Design Guide and Installation
Details for Self-Regulating
Heating Cable

Note:
Fully insulate and weather protect
pipe support if outdoors.

*Glass Tape P/N 1528-01017, 1528-01019

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 Heat Tracing of Line Connection Kits
Mounted Instruments P/N 1548-40000
(2700 Family)
P/N 1548-41000
(2300 Family)

*Glass Tape P/N 1528-01017, 1528-01019

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15
 Design Guide and Installation
Details for Self-Regulating
Heating Cable

* Glass Tape or
Cable Ties (typical)

*Glass Tape P/N 1528-01017, 1528-01019

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 Design Guide and Installation
Heaters Wired Directly Details for Self-Regulating
to Thermostat Heating Cable

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 Design Guide and Installation
Heaters Wired with Details for Self-Regulating
3 Pole Contactor Heating Cable

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 ISO 9001 REGISTERED

233 Florence Street

Leominster, MA 01453
Tel: 978 534-2810
Fax: 978-534-2819
www.rscc-heattrace.com

0419-32000