Low Insulation resistance test on smoke detectors

[King84]

Hi Everyone

Just a question bothering me as you cannot do Insulation resistance test on smoke detectors as they can become damaged so obviously smoke detectors are sensitive but they are also installed on lighting circuit so if perform low insulation resistance test 250V between Live and earth would that be safe or still they should be disconnected first or if not possible then it is a limitation ?

 

[westward10]

Connect the line and neutral together then test to earth at 500v.

 

[littlespark]

Is it possible to disconnect them? Most are twist off, or slide out of the bases.

 

[King84]

SOme of these are badly fitted and I sometime avoid taking them down incase if they dont fit back properly so was wondering if I could test with low IR by using Line,Neture together with earth

 

[Strima]

You can test at 250VDC but the internal circuitry of the heads will probably give you poor readings.

Best to do line/neutral to earth, I tend to do 250VDC first in case of current using equipment still fitted that might throw your results such as switched mode power supplies, the 500VDC if I'm happy to proceed.

I'm guessing this is for periodic inspection rather than new installation?

 

[JBW175]

SOme of these are badly fitted and I sometime avoid taking them down incase if they dont fit back properly so was wondering if I could test with low IR by using Line,Neture together with earth

If they’re badly fitted I’d still want to take them down before testing, then code accordingly and rectify where needed.