Discuss odd N-CPC results in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

A

andekoch

Just looking for general pointers here as to what can cause low (approx 0.3M - 0.4M) readings when doing insulation resistance tests between N and CPC.
Obviously the main earth needs to be removed as well as the main bonding or there are likely to be low (probably zero) results esp on TNCS systems.

Lets assume that there is not a real dead short for now, to state the obvious.

To clarify I am lookin for things like say when doing P - N and you get a 0.3M it is probably a pilot light or RCD fused spur. extractor fan is another low P - N reading cause etc
 
Interesting as n-cpc should be fairly clear.

I would start by whipping off all the accessories and see if there is a trapped neutral in the back box. Thats normally the favorite.

I have had low readings right across the conductors, which is purely down to age.
 
just a general question so assume a typical domestic installation. the last time this happened i isolated the circut completely (ie removed the N and CPC concerned from the consumer unit) and the error went away so there must have been somethign else in the house that was the error but it was not on the outside light spur I was extending.
Was a pain to have to do this since the CU was so jamed up and it took ages to find the relevant N and CPC (not a nice new board with well laid out terminals).
 
Interesting as n-cpc should be fairly clear.

I would start by whipping off all the accessories and see if there is a trapped neutral in the back box. Thats normally the favorite.

I have had low readings right across the conductors, which is purely down to age.


Agreed N - CPC should be clear which made it frustrating when this occured. I would have been interested to trace the fault but (when isolating the circuit in question) it was not on the circuit I was working on and I did not feel like spending the day (or more) on my own time. The owner said there was a plug socket burried behind a cupboard that had never worked so I suspect this could have been the cause. but I will never know unless called back for more work.
 

Reply to odd N-CPC results in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock