84 Guidelines for planning the electrical installationSelecting the power cables General rulesSelect the input power and motor cables according to local regulations. Obey these rules:• Select a cable capable of carrying the drive nominal current. See section Ratings(page 195) for the rated currents.• Select a cable rated for at least 70 °C maximum permissible temperature of conductorin continuous use.• The inductance and impedance of the PE conductor/cable (grounding wire) must berated according to permissible touch voltage appearing under fault conditions (so thatthe fault point voltage will not rise excessively when a ground fault occurs).• 600 V AC cable is accepted for up to 500 V AC. 750 V AC cable is accepted for up to600 V AC. For 690 V AC rated equipment, the rated voltage between the conductorsof the cable should be at least 1 kV.• With US installations, consider the additional US requirements. See Additional USrequirements, page 87.Use symmetrical shielded motor cable (see page 86). Ground motor cable shields 360° atboth ends. Keep the motor cable and its PE pigtail (twisted shield) as short as possible toreduce high-frequency electromagnetic emissions.Note: When continuous metal conduit is employed, shielded cable is not required. Theconduit must have bonding at both ends.ABB recommends symmetrical shielded cable for the input cabling, but a four-conductorsystem is also possible.Compared to a four-conductor system, the use of symmetrical shielded cable reduceselectromagnetic emission of the whole drive system as well as the stress on motorinsulation, bearing currents and wear.The protective conductor must always have an adequate conductivity.Unless local wiring regulations state otherwise, the cross-sectional area of the protectiveconductor must agree with the conditions that require automatic disconnection of thesupply required in 411.3.2. of IEC 60364-4-41:2005 and be capable of withstanding theprospective fault current during the disconnection time of the protective device.The cross-sectional area of the protective conductor can either be selected from the tablebelow or calculated according to 543.1 of IEC 60364-5-54.This table shows the minimum cross-sectional area related to the phase conductor sizeaccording to IEC 61800-5-1 when the phase conductor and the protective conductor aremade of the same metal. If this is not so, the cross-sectional area of the protective earthingconductor shall be determined in a manner which produces a conductance equivalent tothat which results from the application of this table.Cross-sectional area of the phase conductorsS (mm 2)Minimum cross-sectional area of thecorresponding protective conductorS p (mm 2)S < 16 S16 < S < 35 1635 < S S/2
