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klik.system | Specification guide to prefabricated wiring systems
11
Marking of a wiring section rated current
BS 8488 requires the rated current (A) and corresponding
reference method from BS 7671:2008, Table 4A2 to be
distinctly and durably marked on each individual section (see
figure 3.).
BS 8488 states that the required current-carrying
capacity of a system section should be determined by the
system designer by applying rating factors for the specific
installation conditions. This current carrying capacity may be
different from the rated current.
All applicable rating factors must be applied, including those
for grouping, ambient temperature and thermal insulation.
Assuming overload protection and simultaneous overload can
occur, this would be the familiar equation from BS 7671
appendix 4 shown in figure 4.
Figure 3 - Example of rated current
marking on each individual section.
Figure 4 - Equation 2 from BS 7671 appendix 4
to determine the size of cable to be used.
Note: Not all rating factors would necessarily
apply and other equations may be suitable
“ The required current-carrying capacity of
a system section should be determined
by the system designer, by applying
relevant rating factors ”.
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