Two new Wylex RCDs both failed tests

[Farmelectrics]

if it was a neutral earth fault how come it wasn't tripping the rcd straight away. ive had a issiue with rcd that don't reset because of neutral earth fault

 

[steamboatwilly]

if it was a neutral earth fault how come it wasn't tripping the rcd straight away. ive had a issiue with rcd that don't reset because of neutral earth fault

No idea I'm afraid ... not been able to get back there yet to look / check. Maybe I disturbed something somewhere. It is now a new RCD so perhaps the original was indeed faulty

 

[Farmelectrics]

No idea I'm afraid ... not been able to get back there yet to look / check. Maybe I disturbed something somewhere. It is now a new RCD so perhaps the original was indeed faulty

seems a bit strange however if its all tested ok crack on

 

[steamboatwilly]

seems a bit strange however if its all tested ok crack on

It had me fooled. It's all fine now bar that downstairs light circuit (currently disconnected CPC). Luckily the house is vacant so I can pop back there sometime soon.

 

[westward10]

Depends on whether the neutral/earth fault causes an imbalance. Just because you have a neutral/earth fault it should not be assumed the circuit will follow the earth path, circuit impedance may dictate the circuit carries on down the neutral path hence no imbalance.

 

[Lucien Nunes]

The behaviour of an N-E fault is complex and can seem unpredictable. There are paths of different resistances to both neutral and earth for current from the faulty circuit, from other circuits and even from neutrals of other installations when there's no load on this one. How each of the currents divides can be hard to predict; sometimes they will cause nuisance tripping when there is heavy load on, sometimes just failure to test, sometimes the RCD won't reset at all.

What they should do consistently, though, is fail insulation tests, so I am a little surprised that wasn't picked up first.