RCD's not tripping at all

[Walks_23]

Hi all,

Just done an EICR and all tested fine, until I got to the RCD's. It's a dual RCD board, not sure if it's TNCS or TNS as it's a top floor flat fed with T&E.
The RCD's failed to test via the circuits and so I tried the test buttons and they didn't work either. Could it just be both RCD's have failed or am I missing something obvious (which in all fairness is very possible with my brain at the moment!) Could it just be because they are AC type?

TIA

 

[James]

try turning them off and back on a couple of times.
They can get "stuck" with prolonged periods of being stationary.

bottom line, if your tester is going well over 30mA and they are not tripping, then they are faulty.
test button not working is a fail on its own.

 

[timhoward]

The only thing that comes to mind is a daft one - did you have a brain freeze moment and forget to turn the main switch back on?

 

[Intoelectrics]

As Tim said,

It could be possible but not common for both RCD's to fail, unless they have been damaged somehow or stood for a long period of time, as James mentioned. Even so, I'd be suspicious of sticking RCD's and would recommend a swap out even if they prove to be unstuck and test ok.

If it turns out they are faulty then they obviously need replacing.

 

[rewireIT]

Imo once an RCD fails the test button, just get rid and put a new one in.

 

[pc1966]

If the power is on and the fail the self-test button then I would replace them.

Whatever the reason they are not providing the safety benefit expected of them, or cannot demonstrate it when tested. Sometimes devices get stuck and a mechanical cycle or two can fix it, but unless they then pass all tests (test button and ramp, etc, using the MFT) it is still time for a replacement.

 

[Bob Geldoff1234]

Disconnect the output neutral from the RCD on the main neutral connection to remove all the circuits neutrals. Leave all the breakers that the RCD feeds in the off position. Retest the RCD. If it doesn't trip now then the RCD is faulty.

 

[telectrix]

as above. a N-E fault on any curcuit could cause both RCDs to fail to trip

 

[Intoelectrics]

Disconnect the output neutral from the RCD on the main neutral connection to remove all the circuits neutrals. Leave all the breakers that the RCD feeds in the off position. Retest the RCD. If it doesn't trip now then the RCD is faulty.

as above. a N-E fault on any curcuit could cause both RCDs to fail to trip

Yes good point, I've had this situation in the past, never give it a thought in response to the OP!