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Protection
against fault
current
The value of prospective fault current will
need to be assessed when selecting a
distribution board and devices.
For an installation with several distribution
boards there will be different values, so you
will need to assess this at different points.
Section 434 of BS 7671 details the requirements of fault current
protection. Only faults belonging to the same circuit need to be
considered. On a three-phase distribution board, where there
is a mixture of three-phase and single-phase circuits we need to
look at these individually.