Does the switch fuse need to be lower rated than the main incoming fuse?

Question: 

Hi,

When meter tails are over a certain length i know we have to install a switch fuse, but my question is can the switch fuse be the same size as the main incoming one?

For example
Main incoming fuse 100 amp
Switch fuse 100 amp
25mm tails

Or would the switch fuse need to be lower rated than the main incoming fuse?

Thanks

Answer:

Regulation 536.3 requires the co-ordination of equipment by selecting OCPD’s in series so that they provide safety and continuity of service.

Selectivity of OCPD’s for overload are covered in regulation 56.4.1.2 and for short circuit protection, regulation 536.4.1.3.

To meet this requirement we would recommend a lower rating OCPD in the switch fuse.

Technical expert - NICEIC

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