pulling out the few hairs I have left! - INSULATION RESIST.

[paulh53]

but at 0.1m i would expect mcb to trip

0.01M Ohms (10000 Ohms) From phase to neutral or earth would not trip an MCB or RCD, as the leakage current is only approx 23mA

 

[mapj1]

However, I'd not be partcularly surprised if the Meg's range was not that accurate, when well outside the range of expected good readings. However, reading through all the MCBs, all outputs in parallel, possible to circuits with a load still attached, could well give a low reading, when the wiring is really basically OK.

 

[JustCurious]

<< I’ll have the circuits tested individually. If that fails , it looks like the CU could go to the scrap yard as it is that old >>

Thank you to you all: Mike (mapj1) , Paul (paulh53) , Felix , Lectrician and Breezer !
Any opinions on this one, please ? -How do you check CPC continuity which is incorporated inside steel trunking and conduit , since this will create a PARALLEL path ? - RE: three phase installation which also has SWA and MICC cables

Regards.

Cheers to FWL_Engineer too . I am not doing any work, I am just looking at exam and practical issues in order to decide if I should go for an exam in 12 months' time after I go to college, acquire some (more) knowledge, etc

 

[mapj1]

If the conduit is the CPC, then its not a parallel path, it is THE path, and can so be tested in the normal way. If there is a copper CPC plus conduit, and if they dont follow the same route, so must be checked with-out the 'extra' earthing in place, then the places where CPC and conduit join can be seperated, and impedeces checked stand-alone. (usually this means unscrewing switch and socket fronts to separate where CPC and conduit are bonded by the faceplate screws.)
Hope that helps.
regards M.

 

[Big_Spark]

Cheers to FWL_Engineer too . I am not doing any work, I am just looking at exam and practical issues in order to decide if I should go for an exam in 12 months' time after I go to college, acquire some (more) knowledge, etc

That's fair enough Justcurious...Good luck with it when you do it.