I would like some advice on emergency lighting certification. We have used a company to test a site, and a 2nd company to carry out the resulting remedial repairs. How do we go about showing the client that the emergency lights are all tested and working?

There should be a periodic test certificate record in the possession of the RP of the premises and the first company should have completed it or provided a new one. The second company should have completed the emergency lighting fault action record.

Example of the model periodic test certificate and the fault action record can be found in

BS 5266-1:2011 Emergency lighting. Code of practice for the emergency escape lighting of premises appendix H.