3
Heating Cable Repair
38 | nVent.com
nVent.com | 39
Using oxy-acetylene torch, apply heat to the
tip
of
the twisted conductors with a small flame (see
Appendix E) and touch or wipe brazing rod onto the
tip by turning the rod between the fingers. This will
ensure that the flux melts off the rod and onto the
conductors evenly. Take care not to get any flux near
the end of the cable where it might contaminate the
magnesium oxide powder.
Continue heating conductor with the oxy-acetylene
torch (this does not take much heat) and at the
same time touch brazing rod to the end of the
twisted conductors and apply enough silver solder
to form a small bead.
Slightly
fan
torch back and forth several times to
draw the silver solder backwards, about 1/4 in (6
mm), along the twisted conductors. Remove heat.
Brazing rod
Figure 54: Join conductors
Care must be taken to avoid over-heating the
conductors and to avoid depositing an excessive
amount of solder on the twisted conductors.
Break away the flux from the brazed conductors
and snip off the end of the conductors leaving
1/4 in (6 mm) exposed. Use a pick to remove any
flux or carbon which may have contaminated the
magnesium oxide powder.
Pick
1/4 in (6 mm)
Figure 55: Clean face of cable