head banging... help needed!!

[Top-Spark]

Hi all, changed a db today and hay presto... Goodbye RCD!! been testing all day and still can't find the fault!! when I turn any light switch on the RCD trips but only if under load!! Remove the lamps, it doesn't trip!! both light circuits are currently on same RCD aswell!!

 

[onions1066]

Have you not disconnected 1 of your lighting circuits and narrowed it down to the upstairs or downstairs being the problem?

 

[GLENNSPARK]

Murdoch - pme, 0.78 (if memory serves me) !! Good reading... That's not the 'end of' the circuit though (there isn't one) must be under floor in jb for a wall light.... Somewhere!!

eh?...

 

[GLENNSPARK]

Onions... Sockets on other RCD, for this RCD currently controlling up and down lights (2sep circuits but temp on same RCD) have tested at 4 points -one upstairs, 2 down, and at mains and none are tripping <35mA!!

ramp it....

 

[onions1066]

PME 0.78 or do you me TNS.?

 

[Top-Spark]

Onions, yes just downstairs.
Glen I have ramped it and it's >35mA at 0d and 180d?! Puzzling the hell out of me!! On paper there's nothing wrong?! Test results etc but RCD just won't have load!!

 

[Top-Spark]

No defo PME - got a ze of 0.17!

 

[onions1066]

Time to strip the lighting down work out your route they take with resistance readings and bell out each cable to find your problem. It is there somewhere you just need to find it.

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You said 0.78 earlier?

 

[GLENNSPARK]

No defo PME - got a ze of 0.17!

thats better...

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have you measured this with all parrallel paths disconnected?

 

[Top-Spark]

Sorry, though u asked for zs!!

 

[GLENNSPARK]

Sorry, though u asked for zs!!

rite..
do as you have been told and start disconnecting....go point to point....testing as you go...

 

[Top-Spark]

Ahh Glenn, now uv said that I haven't as gas and waters joined 2 main earth In meter box!! Habit of just disconnecting the main earth at db hay!! U lot r ace... Knew I'd overlook something simple!! Ill get proper result 1st thing!! cheers

 

[GLENNSPARK]

Ahh Glenn, now uv said that I haven't as gas and waters joined 2 main earth In meter box!! Habit of just disconnecting the main earth at db hay!! U lot r ace... Knew I'd overlook something simple!! Ill get proper result 1st thing!! cheers

yes..
always remember that just dropping out the main earthing at the dis-boards earth bar is not a guarentee of eliminating parrallel paths...
always look for earth blocks/earth marshalling points...

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Ahh Glenn, now uv said that I haven't as gas and waters joined 2 main earth In meter box!! Habit of just disconnecting the main earth at db hay!! U lot r ace... Knew I'd overlook something simple!! Ill get proper result 1st thing!! cheers

good lad..

 

[SparkieD]

Check 2w on landing/hall defo shared neutral on up & down lts.