Testing pfc

Prospective fault current is required by BS 7671 to be determined at relevant points, which includes switchgear and protective devices (and hence each distribution board).

However, that doesn't mean a measurement has to be taken, and in some cases there are significant risks involved in taking a measurement. See Appendix 16 of BS 7671. In cases where the prospective fault current is high, say much above 10 kA, the resolution of standard loop test equipment can be too high to be relied upon.

Excellent thanks and what if the pfc exceeds the breaking capacity of the protective devices on the distribution boards? 

That depends on whether the appropriate backup protection has been provided, and/or whether there is a conditional short-circuit rating applied for the board with the relevant protective devices.

For example, UK 'consumer units' for domestic use, typically have 6 kA protective devices, sometimes 10 kA with RCDs, but are required to have a conditional fault current rating of 16 kA as per the tests of the National Annex to BS EN IEC 61439-3. The 16 kA conditional fault rating is dependent on having a maximum 100 A BS 88-3 or BS 1361 protective device upstream of the consumer unit

That depends on whether the appropriate backup protection has been provided, and/or whether there is a conditional short-circuit rating applied for the board with the relevant protective devices.

For example, UK 'consumer units' for domestic use, typically have 6 kA protective devices, sometimes 10 kA with RCDs, but are required to have a conditional fault current rating of 16 kA as per the tests of the National Annex to BS EN IEC 61439-3. The 16 kA conditional fault rating is dependent on having a maximum 100 A BS 88-3 or BS 1361 protective device upstream of the consumer unit