Rcd Problems

[grahamkelly]

This is a bit of a mad one and left me scratching my head big time!

just finished a rewire of a 2 bed property and carried out a full installation test, now all tests were satisfactory including the rcd tests......but earlier on in the job i went through an old existing cable whilst chasing and the rcd on the old existing board didnt trip, i thought nothing of it at the time but out of curiosity really i flashed an earth across a neutral today on the new installation and still got nothing from even the new rccbs

so after a while of investigating i found that the rccbs would only respond every now and again (more not working than working), so thinking the rccbs were faulty even though they tested fine using an rcd tester i decided to replace them but it was still in the same situation as before

any ideas anyone??

all rccb links were present and correct inside the board

there is an existing main earth with a ze of 0.20 (tnc-s system)

 

[ryanryan]

you said you 'flashed N to E', did you do this at the terminals of the rccb?

 

[grahamkelly]

no at 2 socket outlets on seperate circuits on seperate rccbs

 

[Des 56]

I would go with the rcd tester resuts
When you flash neutral to earth,you would still require the leakage current from somewhere for it to trip


If there are loads in circuit when they are flashed,it might then come out
With small leakage or fault currents it may never do so