Installation Guide

28 | nVent.com/RAYCHEM
7 POWER SUPPLY AND ELECTRICAL
PROTECTION
In the event of an earth fault or over current interruption, the
device shall not be reset until the cause of the trip has been
investigated by qualified personnel
7.1 Electrical loading
Size overcurrent protective devices according to the design
specification or applicable nVent product literature. If devices
other than those specifically identified are used, consult the
nVent representative for the appropriate sizing information.
7.2 Ground fault equipment protection is required for
each circuit
The metal sheath/braid of the heating cable must be connected
to a suitable earthing terminal
7.3 Residual current (earth fault) protection
nVent insists on the use of a 30 mA residual current device to
provide maximum safety and protection. However, where there
is a marked increase in nuisance tripping, a maximum 300 mA
residual current device may be used.
For heating cables installed in a hazardous area, the use of
residual current devices is normally a condition of their approval.
8 HEATING CABLE TESTING
8.1 Recommendations
nVent recommends insulation resistance test before installing
heating cable; before installing thermal insulation; prior to initial
start-up; and as part of the periodic maintenance.
(see Section 9.2).
8.2 Test method
After completing heating cable installation, the insulation
resistance between the conductors and the braid should be
checked (see Figure 11) using a 2500 VDC megger. Minimum
readings should be 1000 Megohms regardless of the heating
cable length. The installer should record the original values for
each circuit on the installation record sheet (see page 25). If a
thermostat is installed, it should be bypassed.