Tests for copper resistance should also be made to determine if the
splices are electrically perfect; an imperfect splice may cause
considerable trouble. In telegraph and telephone cables the conductors
should be of very soft copper, for in stripping the conductor of
insulation it is very easy to nick the wire, and if of hard drawn copper
open wires will be the result.

All work should be frequently tested for continuity with telephones,
magnetos, or small portable galvanometers. It is only necessary to
ground the conductors at one end and try each wire at the other end. For
this sort of work a telephone receiver used with one cell of some dry
battery is most convenient, and has the additional advantage of
affording a means of communication while testing, and is by far the best
thing for identifying and tagging conductors.

These cables should be frequently tested during the progress of the work
for grounds and crosses with a Thomson instrument, and when the cable is
complete, a careful series of tests of the capacity, insulation
resistance, and copper resistance of each wire should be made and the
exact condition of the cable determined before it is put in service, and
thereafter an intelligent oversight of the condition of the circuits
can thus be more readily maintained.

Where a company has extensive underground service, a regular cable gang
should be in its employ, for quick and safe handling of cables demands
the employment of men accustomed to the work. If the cable has been
properly laid and tests show it to be in good condition before current
is turned on, almost the only trouble to be anticipated will be due to
mechanical injury. Disruptive discharge, puncturing the lead, may occur;