Dead Short after IR testing

[Spazz]

Just had a call off my electrician (one doing council work)

He did a CU change - on testing he IR tested the lighting circuit (500v DC) and got acceptable readings.
When he energized the circuit - RCD trips. Found a dead short between N and E. Investigating now to locate which run of cable/accessory is providing this dead short now. There are no Low Voltage equipment on lighting so nothing could of been damaged.

Any ideas what could of caused this?

 

[AndyL]

100% did an IR Test. When he put the bulb back in it shattered in his hand. All ceiling roses back up and not a clue on what caused it

This is a bit concerning and very confusing, not sure how fault between N&E would ever cause lamp to shatter

 

[growler]

love it when people are asking questions for their 'mate'

 

[somersetsparks]

One ive had when testing is just putting the pendant cover back up has been enough to push the fixing screw into making contact with the cable its screwed through,

 

[Spazz]

love it when people are asking questions for their 'mate'

Considering that I was not working today and im not doing these Council Kitchens anymore - must have been the person working for me.