Installation Guide

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Figure 11
Test between heating cable and braid
Capacitance Test Method
This method uses capacitance measurement (nF) to
approximate the location of a fault where the heating cable has
been severed. It also gives an estimate of total heating cable
length in a non-severed circuit. This reading must be taken at
the power connection and will only work when the heating cable
has passed IR testing. This information is used to calculate
the heating cable output per linear metre or to determine if the
maximum length has been exceeded.
Record the capacitance reading from one end of the heating
cable. The capacitance reading should be measured between
both bus wires twisted together (positive lead) and the braid
(negative lead).
Multiply the measured capacitance with the heating cable’s
capacitance factor as listed in the following table.
Example:
20HTV2-CT
Recorded capacitance = 16.9 nF
Capacitance factor = 2.96 m/nF
Fault location = 16.9 nF x 2.96 m/nF
= 50 m from reading location
As an alternative, capacitance values from both the front and
back end can be used. The ratio of one capacitance value taken
from one end (A) divided by the sum of both A and B (A + B) and
then multiplied by 100 yields the distance from the first end,
expressed as a percentage of the heating circuit length.