We have had to do that a few times, because there is no landlord dedicated supply. We had no choice but to put variations on the certification, and then at each maintenance visit, remind the RP, till they do something.
The main issues.
The risk of a tenant being on a key meter or simply vacating the premises.
The ability to isloate the electrical supply for safety (including maintenance) if the tenant is not available.
The increased likelihood of a tenant switching off the power to the Fire Alarm.
The Likelihood that the tenant will have a systemwide earth leakage circuit breaker.
I am sure that there will be other issues, such as does the installation become a "Part P" notifiable if it derives from within a tenancy, but those above make it clear that it is to be avoided.