HD110301-1 Rev2
Page 12 of 23
STEP 2 – DESIGN CONSIDERATIONS
When a pipe enters the heated area of a building it is important that the cable extends into
the building approximately 12” to ensure the pipe temperature is maintained above
freezing.
When a pipe enters the ground to below the frost line it is important to run the cable well
below the frost line (a minimum of 2 feet) to ensure the pipe temperature is maintained
above freezing.
When a main pipe has a short branch line connected to it, the branch line may be double-
traced (down & back) to eliminate the need for a Tee Splice Kit. Refer to detail in Figure 5.
Heating cable should not pass through the air. When crossing from one pipe to another, the
cable should run through a Flexible Extension (FLEX-E).
Select the cable wattage output to suit the application. A conservative design will specify a
slightly higher wattage output per foot of cable than required. However, this will consume
more electrical power over time and is not required with a correctly designed system.
A lower wattage cable has a longer circuit length. On projects with long runs, this reduces
the number of circuits, thereby lowering component and circuit costs and increasing
reliability by reducing the number of potential failure points in each connection. Always
design to use the lowest wattage heater for the given design conditions – it is bad practice
to use higher wattage cables than necessary.
Insulate all heat sinks (pipe hangars, pipe shoes, valves) in the heat tracing system. Allow
sufficient cable to trace additional heat sinks. Refer to Table 2.
DO NOT expose heating cables to temperatures higher than their temperature ratings.
For valves, install the heating cable so that the valves can be conveniently removed for
servicing.
The type and thickness of thermal insulation will have a direct effect on the amount of heat
required. Longer circuit lengths may be achieved by increasing the insulating thermal value
to lower the cable wattage output required. Refer to Table 1.
Multiple runs of cable may be required on larger pipes with high heat loss.