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Guide to commercial installations | Part 2 Panelboard: Standards and Regulations
11
If there is a three-line 16kA prospective fault current at the
panelboard, then you need to select single pole devices with
a minimum fault current rating of 8kA. This assumes that the
line to neutral prospective fault current is equal to or higher
than the prospective earth fault current.
The manufacturer is responsible for ensuring the capability of
the equipment between the incoming and the outgoing
terminals of the panelboard. This includes busbars and
connections as well as incoming and outgoing devices.
Therefore, the fault current rating is declared for each
panelboard as an assembly in accordance with
BS EN 61439-2, and is not just selected on the short circuit
ratings of the circuit breakers that are employed.
The terminology to define the short-circuit rating of a
panelboard is given in BS EN 61439 as follows:
• Rated short-time withstand current
I
cw
• Rated peak withstand current
I
pk
• Rated conditional short-circuit current
I
cc