RCD test button

[Lesly1]

Hi, can anything else cause a RCD test button to fail, besides a faulty RCD.

 

[cireland]

Possibly D.C. voltages affecting type 'AC' RCD.
If that is the case it should still be replaced.

 

[DefyG]

Hi, can anything else cause a RCD test button to fail, besides a faulty RCD.

Not really as I believe it is just a mechanical feature of an RCD to test the mechanics of the device that it would operate in event of a fault and not 'stuck'!

 

[plugsandsparks]

Hi, can anything else cause a RCD test button to fail, besides a faulty RCD.

NE fault on a load , if RCD is in circuit, so if test button fails, try disconnecting outgoing ccts from RCD

 

[James]

Hi, can anything else cause a RCD test button to fail, besides a faulty RCD.

Lack of earth.

 

[brianmoooore]

Lack of earth.

Not on any RCD I can recall. Test button connects a resistor between one pole on the input side and one of the other poles on the output side, creating a 30mA or so difference (on a 30mA RCD) between whatever current is flowing through those two poles.
No earth connection involved.

 

[James]

Not on any RCD I can recall. Test button connects a resistor between one pole on the input side and one of the other poles on the output side, creating a 30mA or so difference (on a 30mA RCD) between whatever current is flowing through those two poles.
No earth connection involved.

you may well be correct but I have known some rcbo's to not trip when the flylead is disconnected.

 

[brianmoooore]

Possibly an extra test built in to ensure that the earth lead is connected, but not since the days of the old voltage operated earth leakage detectors (yes, I am that old), has there been a requirement for a current to flow in the cpc for said breaker to operate. RCDs detect a difference in the sum of the currents flowing through its poles. The sum should be zero, but if exceeds 30mA, then off it should trip.