Symptoms
Probable Causes
Correction
Insulation resistance is less than
expected or varies with voltage (500,
1000, 2500 Vdc).
Nicks or cuts in heating
cable with or without
moisture present.
Short between braid and
heating cable core or
between braid and pipe.
Crossed bus wires in
core seal.
Check all connections in power, splice, tee, and end seal kits
for cuts in heating cable jackets, or for improper stripping
distances. Restrip heating cable to remove damaged
areas or establish proper distances. If heating cable is
not yet insulated, visually inspect for damage, especially
at elbows and flanges and around valves. If system is
insulated, disconnect heating cable section between
power kits, splices, etc., and test again to isolate damaged
section of cable. Use RAYCHEM DET-2200 fault locator or
other appropriate device to locate fault. Replace damaged
heating cable sections.
Meter needle oscillates rapidly or
indicates charging and discharging.
Arcing created by
damage to insulation or
exposed electrical parts.
Same as above.
Insulation resistance increases
slowly with time.
Moisture present
between energized parts.
Check all connections in power, splice, tee, and end seal
kits for signs of moisture. Dry out connections and retest.
Be sure all conduit entries are sealed, and that condensate
in conduit cannot enter power connection boxes. If no
water is present in connections, isolate sections as
described in correction outlined above. If heating cable
core or bus wires are exposed to large quantities of water,
replace heating cable. Drying the heating cable is not
sufficient, as the power output of the heating cable may
be significantly reduced.
Insulation resistance decreases
rapidly during or after the charging
period.
Heavily wetted surfaces
between energized parts. Same as above.
Circuit breaker (GFPD) trips.
Nick or cut in heating
cable or power feed wire
with moisture present.
Replace damaged cable.
Circuit breaker
undersized.
Resize the circuit breaker and wiring if applicable.
Circuit oversized.
Same as above.
Startup at too low a
temperature.
Same as above.
Defective circuit breaker.
Replace circuit breaker.
WARNING: Fire Hazard. A tripped
ground-fault breaker may mean the
heating cable has been damaged or
improperly installed and must not be
ignored. Sustained electrical arcing
or fire can result. To minimize the risk
of fire if the breaker has tripped, shut
off the power and repair the system
immediately.
Do not attempt to repair or energize
damaged cable. Damaged heating
cable or components can cause
electrical shock, arcing, and fire.
Remove damaged sections at once
and replace them with a new length
using the appropriate
RAYCHEM splice kit.
Connections shorting
out.
To locate shorting problems, follow these steps:
• Visually inspect the power connections, splices, tees,
andendsealsforproperinstallation;correctas
necessary.
• Check for visual indications of damage around the
valves, pump, and any area where there may have been
maintenance work.
• Look for crushed or damaged insulation lagging along
the pipe. Replace damaged sections of heating cable.
Using a megohmmeter, test per installation instructions.
Physical damage to
heating cable causing a
direct short.
Same as above.
Bus wires connected at
the end.
Check end seal junction box to ensure bus wires are
secured properly in terminal block. The heating cable may
have been permanently damaged by excessive current
and may need to be replaced.
Excessive moisture in
connection boxes or
splices.
Dry out and reseal connections and splices. Using a
megohmmeter, test per installation instructions.
TROUBLESHOOTING GUIDE
nVent.com
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