RCD not tripping on test

[jmc1683]

I am doing complete installation test on domestic house, working off two dual RCD distribution boards. There are socket rings as well as other circuits connected on DB1 and everything seems to be testing ok.

on DB2 I have the following circuits on one RCD,
Utility Ring, Downstairs sockets, Kitchen appliance, Lights kitchen, lights stairs.

the ring sockets are not tripping the RCD. Here are their details,

Utility Ring
L-L 0.26
N-N 0.26
E-E 0.41
R1 + R2 0.27
Ins Res +999 +999

Downstairs sockets
L-L 0.26
L-L 0.26
E-E 0.48
R1 + R2 0.25
Ins Res +999 +999

Kitchen App
L-L 0.19
N-N 0.19
E-E 0.28
R1 + R2 0.16
Ins Res +999 +999

 

[GLENNSPARK]

I was looking at that aswell, didnt investigate, you think that has something to do with it? RCD should still trip on test right?

eh?.....

 

[LED Lighting]

No faulty unit tripped at 10mA after hitting Test Button - new unit tripping at 28mA

By the way this RCD was less than 6 months old!!!
I installed it last September - Ze 0.18 on a TN-S

 

[jmc1683]

no, will do that. RCD seems fine though. I'm gonna look into that earth reading from 1st floor sockets though, didnt get chance to yet

 

[GLENNSPARK]

no, will do that. RCD seems fine though. I'm gonna look into that earth reading from 1st floor sockets though, didnt get chance to yet

and what makes you think its the CPCs?

 

[GLENNSPARK]

so..once youv sorted out your end to ends....you can just jolly well go round the points again on that circuit for a real value of (R1 R2)....cant you...

- - - Updated - - -

this is sounding more and more like the same old farce....

 

[jmc1683]

well i noticed the readings from 1st floor sockets were strange, and someone else pointed it out here just few mins ago....

L-L 0.79
N-N 0.79
E-E 0.52

 

[Octopus]

no, will do that. RCD seems fine though. I'm gonna look into that earth reading from 1st floor sockets though, didnt get chance to yet

What is the Ze? Surely you got this reading first!

 

[LED Lighting]

well i noticed the readings from 1st floor sockets were strange, and someone else pointed it out here just few mins ago....

L-L 0.79
N-N 0.79
E-E 0.52

Those readings are R1, R2, Rn readings and they look fine to me!

R2 is 66% of R1/Rn

 

[GLENNSPARK]

Those readings are R1, R2, Rn readings and they look fine to me!

R2 is 66% of R1/Rn

eh?....try 1.67 for a 2.5/1.5...

 

[jmc1683]

0.19, already answered that

 

[spark 68]

Those readings are R1, R2, Rn readings and they look fine to me!

R2 is 66% of R1/Rn

It is r1, r2 and rn for a start on the end to ends, and his r2 is lower than is r1 and rn, it should be 66% higher for 2.5/1.5 T&E

 

[LED Lighting]

It is r1, r2 and rn for a start on the end to ends, and his r2 is lower than is r1 and rn, it should be 66% higher for 2.5/1.5 T&E

Sorry just seen my mistake - sorry!

 

[spark 68]

Deleted: blonde moment Lol

 

[Octopus]

0.19, already answered that

I'm guessing you mean that the Ze is 0.19. Can you set the RCD and does the test button work? I would now venture to suggest that the CPC has a voltage on it.

 

[jmc1683]

sorry mate, you must have joined us late. i already answered everything your asking in the first posts. RCD is setting, test button working, all circuits working fine. checked all connections, swapped RCD....

 

[Octopus]

sorry mate, you must have joined us late. i already answered everything your asking in the first posts. RCD is setting, test button working, all circuits working fine. checked all connections, swapped RCD....

Voltage on the CPC?

 

[dagrat]

It is r1, r2 and rn for a start on the end to ends, and his r2 is lower than is r1 and rn, it should be 66% higher for 2.5/1.5 T&E

Not necessarily, I would agree on an initial verification it should be 1.67 higher, but from what the op says this is an existing installation and the low r2 is probably due to parallel earth paths so not really a problem

 

[Risteard]

well the results from original RCD on DB1,

utility ring
times 1 - 27.2 ms
times 5 - 8.18 ms

downstairs sockets
times 1 - 27.4 ms
times 5 - 7.98

I didnt record the results after i swapped RCD, just that it did trip on test

One RCCB can't have two different trip times.

 

[spark 68]

Not necessarily, I would agree on an initial verification it should be 1.67 higher, but from what the op says this is an existing installation and the low r2 is probably due to parallel earth paths so not really a problem

Agreed, but as this is domestic and subject to being tested properly (end to ends) ie. disconnected at the CU/DB end, you would need at least two parallel paths to lower the reading, it should warrant further investigation to rule this in or out when you do not get the expected readings, especially while fault finding.