R1+R2 continuity both ways

[PEG]

I'm not brave enough,to ask what the readings were,before the board swap...

 

[Anthony_wayne]

No damp areas? Almost like there is something else in the circuit? Or when you IR'd did you have cpc on the bar still with neutral connected?

 

[dmxtothemax]

could there be a switch with built in ilumination ?

 

[Pete999]

I'm not brave enough,to ask what the readings were,before the board swap...

Get the impression that there wasn't any testing before CU change hope I'm wrong

 

[Deleted member 9648]

It always mystifies me when an (alleged) low IR is encountered that a neon always seems to get the blame. This would only happen on a L-N test, the OP has not specified what IR test has been carried out but I doubt it's L-N. Or is it OP?

 

[shinypen]

Tested polarity of incoming supply, ze@ board, direct zs and pfc of several points on system and bonding before hand. All were fine. The board was a mess and a real tangle of too short cables.

I freely admit to being new to this so as an aside is it really common practice to do a full set of tests on every part of every circuit before a board change?

In this instance it's my board and any problems that arise need to be fixed by me anyway. Surely safer and easier once a new board in place.

 

[shinypen]

No damp areas? Almost like there is something else in the circuit? Or when you IR'd did you have cpc on the bar still with neutral connected?

Thanks anthony. This is helpful. I did indeed have the cpc still connected to the bar. Hadn't realised this could introduce problems. I'll update this post at the end of the day with the results! Hopefully just that and an incorrect ir test...

 

[Pete999]

Yes it's always best to IR test before CU change why? because you are adding RCDs to the system, and any IR N-E L-E will trip the RCD, nothing more frustrating than changing CU all nice and neat, then do your testing, no bonding IR faults file:///C:/Users/Pete/Downloads/Best-Practice-Guide-1-Issue-3-(1).pdf

 

[shinypen]

Yeah can see the logic. Point taken. IR tests are such a pain though!

 

[Pete999]

Yeah can see the logic. Point taken. IR tests are such a pain though!

Even worse pain is not IR testing and the RCDs trip and you have to start ripping your nice neat CU to bits to find the fault

 

[David M]

You still need to clarify which conductors you IR tested between to get the 0.7Mohms (assuming this is what you meant). If you do thorough tests then you can start to eliminate the possibilities causing the fault (again assuming there is one). Its good practice to be methodical with your testing rather than just rushing and second guessing.

 

[shinypen]

Thanks everyone. Lesson learnt. My error on both.

The cpc continuity is now fine. I'd left cpc in cu met bar. When I removed it the readings were fine.

again, my error with ir. Reading was as stated by others actually 0.7 m ohms. Looks like I've got an issue with the lighting insulation.

Methodical step by step testing the correct way I completely agree, but hadn't realised leaving cpc in met caused errors which lead me down the wrong path. Thanks.

 

[shinypen]

To clarify. Original ir test was cpc to line. Done all ir test combinations now.

 

[Anthony_wayne]

It's less the leaving the CPC in the main earth bar and more to do with the neutral conductor being left connected. The correct prescribed method is to leave the cpc connected, but remove both line conductors.

 

[David M]

Thanks everyone. Lesson learnt. My error on both.

The cpc continuity is now fine. I'd left cpc in cu met bar. When I removed it the readings were fine.

again, my error with ir. Reading was as stated by others actually 0.7 m ohms. Looks like I've got an issue with the lighting insulation.

Methodical step by step testing the correct way I completely agree, but hadn't realised leaving cpc in met caused errors which lead me down the wrong path. Thanks.

I understand that you are relatively new to the industry (you mentioned this earlier in the thread) Inspection & testing isn't just about taking readings and checking them against what is accepted. Its also about understanding what the tests are for, why the readings are what they are and the implications of such, whether acceptable or not.
Fault finding requires understanding and knowledge of testing, also experience which has to be earned.
I have watched many a spark just go through the motions without any thought to why he/she is doing the tests in the first place.
That's why in my opinion methodical thorough testing and a clear understanding of what you are doing and looking for is vital.
Its great that you are questioning your readings, but its important that those readings are accurate, appropriate and correctly interpreted.

 

[Richard Burns]

It's less the leaving the CPC in the main earth bar and more to do with the neutral conductor being left connected. The correct prescribed method is to leave the cpc connected, but remove both live conductors.

It should be clear that this is the action to take for IR testing and that continuity testing should normally be undertaken with no possibility of parallel paths reducing the reading.

 

[Anthony_wayne]

It should be clear that this is the action to take for IR testing and that continuity testing should normally be undertaken with no possibility of parallel paths reducing the reading.

Agreed mate, though we were talking about his IR test so thought that was clear enough. I see a lot of experienced sparkies still disconnecting the CPC for the IR tests, they don't believe it changed until you show them GN3.

 

[shinypen]

-

 

[shinypen]

All sorted now. Sorry for the confusion and thanks for all the input.

 

[westward10]

So this had nothing to do with R1+R2 then