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Main switch short circuit capacity.

wessex
Some guidance please.

Three phase TN-S supply from a private 800 kVA transformer. Distribution via a 240mm2 4 core SWA approx 20m in length from a transformer mounted feed pillar and protected by 315A fuses. At the intake position 100A BS 1361 type II fuses are fitted. I was looking to install a REC 4 main switch down stream from which would be three phase distribution by 10kA rated MCB's. My question is about the suitability of the main switch and its short circuit capacity at it's point of installation with regard to prospective fault current at this point which will be greater than 16kA or do the BS 1361 afford adequate protection for the switch ? Your thoughts please.
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    No, given DNO max PFC for such an installation. I do not expect the REC 4 to be switching at fault levels and will be feeding two 3 phase boards fitted with 10k protective devices. Tails less than 2m in length. Not impossible introduce a fault during maintenance, but the same could be expected of the main switch in each DB if only isolating from there.


    Many thanks all.
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  • 0
    No, given DNO max PFC for such an installation. I do not expect the REC 4 to be switching at fault levels and will be feeding two 3 phase boards fitted with 10k protective devices. Tails less than 2m in length. Not impossible introduce a fault during maintenance, but the same could be expected of the main switch in each DB if only isolating from there.


    Many thanks all.
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