Owner's manual

SR Heating Cable Selection and Design
Use table 1 to select the heating cable size for insulated metal pipes and use table 2 to select heating cables for
insulated plastic pipes. Read across the table to find the pipe size, then drop down the column to the row
corresponding to the lowest design air temperature column for the application and chose the thickness of the
insulation that will be used. The cell that intersects will give the power (watts/ft.) of the cable required and it may also
have a number (2) in the cell which represents using 2 cables. Run the cable straight along the bottom of the pipe. If
two cables are required, attach them at the 4 and 8 o’clock positions as shown in figure 1 page 4. Spiral tracing the
cable is not recommended as it is labor intensive.
Lowest
Air Temp.
Insulation
Thickness
1/2” 3/4” 1” 1-1/4” 1-1/2” 2” 2-1/2” 3” 4” 6” 8”
0ºF
(-18ºC)
1/2” 3 3 3 3 5 5 5 5 8 8 10
1” 3 3 3 3 3 3 3 5 5 8 8
1-1/2” 3 3 3 3 3 3 3 3 5 5 5
2” 3 3 3 3 3 3 3 3 3 5 5
-20ºF
(-29ºC)
1/2” 3 5 5 5 5 5 8 8 10 10
*
1” 3 3 3 3 3 5 5 5 8 8 10
1-1/2” 3 3 3 3 3 3 3 5 5 8 8
2” 3 3 3 3 3 3 3 3 5 5 8
-40ºF
(-40ºC)
1/2” 5 5 5 5 8 8 10 (2) 8 (2) 8 (2) 10
*
1” 3 3 3 5 5 5 8 8 8 10 (2) 8
1-1/2” 3 3 3 3 3 5 5 5 8 8 10
2” 3 3 3 3 3 3 3 5 5 8 8
3” 3 3 3 3 3 3 3 3 3 5 5
Lowest
Air Temp.
Insulation
Thickness
1/2” 3/4” 1” 1-1/4” 1-1/2” 2” 2-1/2” 3” 4” 6” 8”
0ºF
(-18ºC)
1/2” 3 5 5 5 8 8 8 10 (2) 8 (2) 10
*
1” 3 3 3 5 5 5 5 5 5 8 8
1-1/2” 3 3 3 3 3 3 5 8 8 8 10
2” 3 3 3 3 3 3 3 5 5 8 8
-20ºF
(-29ºC)
1/2” 5 5 8 8 10 10 (2) 8 (2) 8 (2) 10
* *
1” 3 3 5 5 5 8 8 8 10 (2) 8 (2) 10
1-1/2” 5 5 5 5 5 5 5 8 8 10 (2) 8
2” 3 3 3 3 3 5 5 5 8 8 10
-40ºF
(-40ºC)
1/2” 8 8 8 8 10 10 (2) 8 (2) 10
* * *
1” 5 5 5 8 8 8 10 10 (2) 8
* *
1-1/2” 5 5 5 5 5 8 8 8 10 (2) 8 (2) 10
2” 5 5 5 5 5 5 5 8 8 10 (2) 8
3” 3 3 5 5 5 5 5 5 5 8 10
Table 1' – SR cable selection for metal pipes (w/ft.)
Table 2' – SR cable selection for plastic pipes (w/ft.)
' The tables are based on a using fiberglass insulation or equivalent while maintaining a 40ºF (4ºC) pipe
temperature with a 10% safety factor and 20 mph wind speed.
* Contact King for the proper cable selection
Rev 11.04.12
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