A few questions about the COC from a contractors viewpoint.
How long is a COC valid for?
For what timespan Is the electrical contractor, person who signs the COC responsible for the condition of the installation?
If equipment, switchgear breaks down after a COC is issued is the contractor responsible?

My reason for these questions is that I sometimes get comebacks on COC issues, only from private, residential installations up to nine months after issuing. This becomes a waste of time for me.

Anybody else have these problems?

Thanks
Eric