That's actually a matter of debate. An EIC issued for the replacement of a DB is simply certifying the DB installation as compliant with BS7671 as this is the scope of work. However, there is a need to ascertain that the safety of this is not impaired by the existing installation and will not impair the safety of the existing installation. So it's necessary to ensure that the protective devices (assuming of a different type) will operate in the required time and that the connections you have made in the DB are satisfactory. So some would argue that this can be met by verifying cpc continuity to the first point on the circuit as opposed to the last. It's actually a bit of a grey area as you are not in any way certifying the existing installation (although you should make any necessary comments on it in the appropriate section of the EIC).As we all know a fuseboard would require a full certificate of tested circuits.