Page 269 - Electrical Safety of Low Voltage Systems

252 Chapter Fifteen

FIGURE 15.10 Person in contact with an EXCP during faults of submersed
items.
voltage, with respect to the absence of contact, with potentially harm-
ful consequences.
Thus, to reduce the risk of electrocution, supplementary equipo-
tential bonding must be employed in pool areas as per IEC 60364–7-
8
702. All the ECPs and the EXCPs (e.g., metal ladder, diving-board’s
metal supports, hand railings, re-bars in concrete, etc.) located within
Zone 0, 1, and 2 (where Zone 1 is in the pool itself, Zone 2 extends 2 m
beyond Zone 1 and 2.5 m above it, and Zone 3 extends a further 1.5 m
beyond Zone 2) must be connected together. This equipotential bond-
ing connection must be realized by using an insulated conductor
of adequate cross-sectional area. The supplementary equipotential
bonding, which is in addition to the main equipotential bonding, will
greatly reduce the voltage gradients in fault conditions.

15.6 Electrical Safety in Restrictive
Conductive Locations
9
IEC 60364–7-706 defines restrictive conductive locations (RCLs) as
the locations in contact with the earth and where workers may come
into bodily contact with large areas of their conductive constituting
material (e.g., metal tanks, wet tunnels, transmission towers, etc.). The
extended bodily contact may be due not only to the RCLs’ reduced
dimensions, which also restricts the freedom of movement, but also
possibly to the nature of the task workers must perform. The hazard is