CABLES, WIRES AND CABLE INSTALLATION PRACTICES 1919.3 Composition of Power and Control Cables
The composition of a power cable is dependent upon the rated voltage at which it will be expected
to operate continuously without breakdown.
IEC60038 gives the standard voltages for electrical equipment. However, for cables the AC rms
voltages are defined for example in IEC60502, in terms of their line-to-earth and line-to-line values.
See Tables 9.6 and 9.7. Table 9.7 is derived from BS6622.
Note that occasionallyuois quoted as the value obtained by dividinguby 1.732 and rounding
to one decimal place.uois derived from IEC60038.
IEC60502 covers the construction and factory testing of polymeric solid insulated cables in
the voltage range 1000 to 30,000 volts. IEC60183 gives guidance on the selection of cables for high
voltage systems. BS6622 is similar to IEC60502 but is restricted to cables operating at voltages
between 6600 and 33,000 volts, with screened XLPE or EPR insulation. BS5467 covers unscreened
thermosetting insulated cables that operate between 1000 and 3300 volts; hence the standard is
reasonably applicable to low voltage systems e.g. 380, 400, 415, 440, 600 and 750 volts (line to
Table 9.6. IEC standard rated voltages of power cables
Line-to-earth
voltage
uoLine-to-line
voltage
uMaximum value of the highest
system line-to-line voltage
um
600 1,000 —
1,800 3,000 3,600
3,600 6,000 7,200
6,000 10,000 12,000
8,700 15,000 17,500
12,000 20,000 24,000
18,000 30,000 36,000Table 9.7. UK standard rated voltages of power cables
Line-to-earth
voltageLine-to-line
voltageMaximum value of
the highest system
line-to-line voltage
uo uu∗mNote a)
600 1,000 —
3,800 6,600 (8,000)
6,350 11,000 (13,200)
8,700 15,000 (17,500)
12,700 22,000 (26,400)
19,000 33,000 (39,600)
Note a) This column is not shown in BS6622 but is included
to be consistent with Table 9.6 where a 20% upward
margin is added touto obtainumbefore rounding
is applied.
Note b) A method of rounding numbers upwards or downwards
is given in Appendix B of IEC60502.