Electrical wiring and switchgear

Pages:89-90
 
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B9 Electrical wiring and switchgear
B9.1. General
B9.l.l. In view of its importance from the point of view of
safety, electrical wiring associated with lifts should be designed
and installed with the utmost care. The wiring should be in
conformity with the rules in force in the country where the lift is
installed.
B9.l.2. Every precaution should be taken to prevent incidents
and accidents that could result from accidental contact with con-
ductors or from insulation faults to earth or between conductors.
In particular, one or more insulation faults to earth should neither
cause the lift to start nor render the safety devices ineffective.
B9.2. Protection of motors
B9.2.l. Lift motors should be protected against overloading
and short circuits.
B9.2.2. Every measure should be taken to prevent damage
to equipment in case of failure of a single phase of the electricity
supply.
B9.3. Contactors and relays
B9.3.1. In view of the fundamental role which contactors and
relays play with regard to safety, such equipment should be
selected with the utmost care. It should be of sound design and
construction, and its specifications should correspond to the oper-
ating conditions.
B9.4. Voltage for control and safety circuits
B9.4.l. The r.m.s. voltage between conductors in controland
safety circuits should not exceed 250 volts.
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