Rcd not tripping

[Doctorsparks]

I'm stumped, fitted new cu in one bed house today RCD would not trip using test button or on test. The only time it trips is when a load is put onto socket circuit, or the socket on the cooker isolator, no faults have been found during testing.
Its a TNC-S system ze of 0.16ohms IR of >999 on all circuits, zs good on all circuits.

i thought it may have been a defective RCD so I replaced it but no join? I have tested both RCD's on my board when I got home both worked!

Any ideas?

 

[Deleted member 9648]

Are you certain the RCD was connected correctly...polarity?,load and mains sides correct?
Also test the RCD with the tester directly on the load terminals with nothing else connected.

 

[Meggerman]

Try connecting neutral and earth the correct way around.

 

[Sintra]

Sounds like a neutral on the wrong bar.

 

[Meggerman]

Sounds like a neutral on the wrong bar.

that would still trip when carrying out RCD test

 

[Doctorsparks]

Neutrals all in correct bar polarity correct,

also tried testing RCD direct with nothing else connected

 

[Deleted member 9648]

Neutrals all in correct bar polarity correct,




also tried testing RCD direct with nothing else connected

It's either a faulty RCD or it's not connected correctly. Have another look.

 

[Paul.M]

Is it a ring with a neutral in the wrong bar? Had that before

 

[KFH]

I have occasionally tested an RCD at the L-N output, wondered why it would not trip and then given myself a good kicking for being so stupid. The test button always worked though.

If the RCD won't work with anything connected something simple is wrong, there were some RCDs that needed a few meters of cable atttached or they would not work, cannot remember the make though. Have you tried testing from the accessory? Not GN3 method but would give you more ideas. The test button should always work though.

Failing that contact the manufacturer.

Good luck.

 

[jaypp]

if it worked when you tested it at home, then go back and re-fit (supply only) . check you have correct voltage l-n supply side, switch on and check load side then test. remember, it works by measuring imbalance.

 

[Lucien Nunes]

Might be worth double-checking the IR for evidence of N-E faults on any finals, not just the ones that cause tripping. A hard N-E short downstream of the RCD can prevent the test button working as well as failing tests with the MFT.

 

[GLENNSPARK]

Might be worth double-checking the IR for evidence of N-E faults on any finals, not just the ones that cause tripping. A hard N-E short downstream of the RCD can prevent the test button working as well as failing tests with the MFT.

......:yes:

 

[Deleted member 9648]

Might be worth double-checking the IR for evidence of N-E faults on any finals, not just the ones that cause tripping. A hard N-E short downstream of the RCD can prevent the test button working as well as failing tests with the MFT.

OP states IR >999 megs though.....mind you we've heard that one before.

 

[Octopus]

Disconnect the neutrals 1 by 1 and see what happens. Defo something not right

 

[Darkwood]

What make of RCD is it.... ??

 

[Octopus]

1 bed house - how many circuits are there?

 

[Doctorsparks]

It's more of an annex. It's got cooker, one ring and two lighting circuits, it's just been renovated none of the wiring has been changed I'm just upgrading the board and earthing.

Thanks for for all the advice am there now going to disconnect everything re test and reconnect.

It's an excel?

 

[Octopus]

So you've got a dual RCD board with 4 circuits??

 

[Doctorsparks]

No it's a signal 5 way board. Sorry should have said that at the start.

 

[Octopus]

No it's a signal 5 way board. Sorry should have said that at the start.

Not sure that having all the circuits on 1 rcd in an annexe is a particularly good idea!