Faulty rcd?

[Marbles]

Domestic installation, rcd tripped on supply to garage which then feeds a barn 25 metres away via swa. supply cable to garage is swa and tests out fine on insul res and continuity as does swa to barn. connect any load to con unit in barn even with no earth and rcd trips? Circuits in barn show healthy insul res readings? any ideas chaps?

 

[StuSpiers]

did you do a full rcd test + ramp test.

 

[Marbles]

ran out of time today will try tomorrow, seems strange that with good insul res readings the rcd trips even with a pendant connected across supply?

 

[StuSpiers]

Well an rcd test will take the guess work out.

did you carry out all IR tests?

L - N, L - E, N - E

Is pme exported?
or is it on a seperate spike?

 

[Taylortwocities]

Is this a brand new installation, or an existing one that has mysteriously started to have this problem.

If it's new, it sounds like a neutral in the wrong busbar, or neutral link not taken out between busbars in an RCD consumer unit.

 

[Marbles]

its an existing installation with a new 17th edition twin rcd board bin added, yes insul res tests done between all conductors?

 

[adamh]

does the test button on the rcd work?

 

[Marbles]

yeah test button is functioning

 

[adamh]

as others have said do a ramp test on the rcd. If all is well try disconnecting each circuit individually and then loading the installation to rule out the possibility of parallel paths.

 

[Deleted member 9648]

its an existing installation with a new 17th edition twin rcd board bin added, yes insul res tests done between all conductors?

Are you saying you've replaced the CU to an existing install?....if so you've got a N in the wrong bar.

 

[Farmelectrics]

Got all the makings of neutral in wrong bar check

 

[Taylortwocities]

yeah test button is functioning

That is NOT how you test an RCD.

The test button is a very basic functional test.

From the sound of it "someone" has done a board swop and mixed up the neutrals.
That "someone" also has not done the required tests on the existing and the altered installation.

 

[telectrix]

check also the manufacturers internal tails in the CU. it is not unheard of to find an incorrect connection.

 

[Octopus]

Anything plugged in?

Got called back to a CU change, which I had completed on Friday, on Saturday morning - customer had tripped the RCD when plugging in a 4 way extension. I took the cover off the plug of the extension and the N-E were reversed. He did look a tad embarrassed!

 

[Marbles]

neutral connection for a lighting cct found to be in the wrong bar on investigation, have done new checks for customer and circuit is behaving itself. rcd tests were o.k. thanks