EICR - RCD Wont trip on test button

[mbu2ns]

Hi all
Still got a hangover from saturday but im struggling with one

EICR, everything tests ok until i press the button on the RCD and it doesnt trip.

Tried 2 spare RCDs same thing.

When i disconnect the sockets Neutral from the busbar it then works.

Type AC 30ma 80A RCD

What am I missing?

Thanks in adavance
Mick

 

[westward10]

Is there a fault on that circuit?

 

[mbu2ns]

Is there a fault on that circuit?

No fault everything tested ok

 

[mainline]

Is the IR N to Cpc definitely OK.

Is it only the socket (i assume ring final) circuit that allows the rcd to trip when disconnected.

 

[mbu2ns]

Is the IR N to Cpc definitely OK.

Is it only the socket (i assume ring final) circuit that allows the rcd to trip when disconnected.

Yeh when i disconnect the neutrals at the DB for the socket ring, the button works

IR is clear on all circuits

 

[Tom256]

Yeh when i disconnect the neutrals at the DB for the socket ring, the button works

IR is clear on all circuits

Are the CPC's connected to the Protective Earth or disconnected from the terminal during the IR test between Live conductors and Earth?

 

[westward10]

It is the most common cause a neutral to earth fault. Have you removed anything plugged into the circuit?

 

[mbu2ns]

It is the most common cause a neutral to earth fault. Have you removed anything plugged into the circuit?

Empty house nothing plugged in,

IR the sockets in question seperate after rcd wont trip. All clear

 

[westward10]

As in #6 are you leaving the cpcs connected when testing.

 

[mbu2ns]

As in #6 are you leaving the cpcs connected when testing.

No i removed and tested after rcd test button wouldnt work

 

[Tom256]

No i removed and tested after rcd test button wouldnt work

The IR test is done with the CPC's in the Earth Terminal.

 

[mainline]

No i removed and tested after rcd test button wouldnt work

What earthing system is it ?

If it definitely is the ring final, I would be disconnecting/splitting it to see if I could narrow it down.

 

[mbu2ns]

What earthing system is it ?

If it definitely is the ring final, I would be disconnecting/splitting it to see if I could narrow it down.

As soon at the neutrals are disconnected the button works

TNS earthing system

Im going back tomorrow morning see if can solve it

 

[mainline]

As soon at the neutrals are disconnected the button works

TNS earthing system

Im going back tomorrow morning see if can solve it

Can you temporarily wire in a rcbo to the ring final and see if that fails to trip ?

 

[westward10]

Redo the IR but leave the cpcs connected. As already mentioned never disconnect cpcs to carry out an IR test.

 

[mbu2ns]

Redo the IR but leave the cpcs connected. As already mentioned never disconnect cpcs to carry out an IR test.

I done it connected 1st then removed them to test just that circuit

 

[PS Electrics]

I done it connected 1st then removed them to test just that circuit

Just a thought but are your spare RCD's Brand New?

https://engx.------.org/f/wiring-and-regulations/28594/cause-of-rcd-not-tripping-with-test-switch

The above was posted 3 years ago and they had the same problem turns out all 3 RCDs were faulty

They were second hand parts from a specialised supplier because new parts were not available but you may have the same issue?

 

[mbu2ns]

Just a thought but are your spare RCD's Brand New?

https://engx.------.org/f/wiring-and-regulations/28594/cause-of-rcd-not-tripping-with-test-switch

The above was posted 3 years ago and they had the same problem turns out all 3 RCDs were faulty

They were second hand parts from a specialised supplier because new parts were not available but you may have the same issue?

Yeh mate they were brand new, i changed the sockets in the lounge and it started working, strange because everything tested out ok before and after changing sockets

 

[HappyHippyDad]

Yeh mate they were brand new, i changed the sockets in the lounge and it started working, strange because everything tested out ok before and after changing sockets

Argh....!
We need IR figures, not 'it tests ok'.
Now we're all thinking 'I bet there was a N-E fault.

 

[mbu2ns]

Argh....!
We need IR figures, not 'it tests ok'.
Now we're all thinking 'I bet there was a N-E fault.

It was >999 on all, tested cables connected and individually, he ce the reason i came on here to ask for ideas