RCD tripping 1/2 rated PME system

[deejaydee]

Hi all I have a problem with a test I have done today.
17th duel board MK
PME system 100A 1361/ ZE 0.10
Rcds trip at ½ rated ive removed all load from rcds, straight on the tails no bonding cpc or cpc of any circuits, only the live natural and earth from the electricity board and it still trips at half rated,
I have tried 4 rcds to make sure that the dbs rcds are faulty but they still trip as well
Tester I new megger MFT1552 multi function works fine as ive checked it at home tonight on my cu and no problems.

Any ideas????

 

[Spark123]

What do they trip at on ramp test?

 

[deejaydee]

15ma but have tryed 2 new rcds just incase they maybe faulty and all do the same,not other circuits are connected,so no chance of any leakage from the clients wiring

 

[Spark123]

Do you have another RCD tester you can try them with?
It could just be a faulty batch of RCDs.

 

[deejaydee]

no tried 2 different makes just to be sure.

 

[securespark]

Well, it's either the RCD's or the tester....

Try a different tester.

Are you absolutely sure that all RCD's have been tested in complete isolation?

 

[securespark]

Could it be a flaky NE connection on the supply side??

Have you wired up the "faulty" RCD's on an independent supply & tested them again?

 

[deejaydee]

yes i have tried them at home and work ok as does the tester.

 

[securespark]

All I can suggest then is to get the DNO to check the PME connection coming into that property.

 

[Lectrician]

Are they DC sence types? (white fly lead earth).

 

[Spark123]

You only need to connect phase and earth to do RCD testing with the MFT btw.