Test Procedures
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9.3 Power Check
The power output of Self-Regulating and
Power-Limiting cable is temperature-sensitive
and requires the following special procedure to
determine its value.
1 Power the heating cable and allow it to stabilize for
10 minutes, then measure current and voltage at the
junction box. If a thermostat or controller is used, refer
to details below.
2 Check the pipe temperature under the thermal
insulation at several locations.
3 Calculate the power (watts/ft) of the heating cable by
multiplying the current by the input
voltage and dividing by the actual circuit length.
Power (w/ft or m) = Volts (Vac) x Current (A)
Length (ft or m)
Ambient-sensing controlled systems
If the actual ambient temperature is higher than
the desired thermostat setting, turn the thermostat
setting up high enough to turn on the system, or (with
some models) manually set the selector switch to the
ON position.
• Turn on the main circuit breaker.
• Turn on the branch circuit breakers.
• After a minimum of ten minutes, measure the
voltage, amperage, ambient temperature, and pipe
temperature for each circuit and record the values
in the “Installation and Inspection Record” (refer to
Section 11). This information is needed for future
maintenance and troubleshooting.
• When the system is completely checked out, reset the
thermostat to the proper temperature.
Line-sensing controlled systems
Set the thermostat to the desired control
temperature, or to a setting high enough to turn
the circuit on if the pipe temperature is above
the control temperature.
• Turn on the main circuit breaker.
• Turn on the branch circuit breakers.
