Insulation resistance testing for a MEW.

Hi I am looking for advice and opinions on what's acceptable for testing and recording insulation resistance on a MEW.

I am still training, apologies if this is not the most appropriate place to post.


I have just added an isolator switch for my cooker extractor hood and tidied up the wiring for a couple of lights, all of this on the downstairs lighting circuit.


Due to the number of LED lights, dimmers and PIR's it's impractical to do an insulation resistance test at 500V on the circuit as I would have to disconnect virtually every fitting. I therefore decided to link line and Neutral, then test between them and earth at 250V for the entire circuit plus test the wiring for the isolator switch and extractor hood as normal at 500V before connecting to the circuit.

I assume this is acceptable, but then what do I record on the MEW certificate. My initial thought is to record the result I achieved for the cooker hood circuit at 500V in the test results.

Then in comments on existing installation record something like Insulation test results recorded are for cooker hood wiring only. Due to sensitive devices entire lighting circuit tested at 250V L-E achieving a result of 9 Mohms.


What would you do in this situation?


Thanks


Alan