RCD test button

Lesly1 · 2024-12-11T07:25:11+0000

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

cireland · 2024-12-11T07:53:59+0000

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

DefyG · 2024-12-11T08:02:45+0000

Lesly1 said:
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 · 2024-12-11T09:43:34+0000

Lesly1 said:
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 · 2024-12-11T14:02:58+0000

Lesly1 said:
Hi, can anything else cause a RCD test button to fail, besides a faulty RCD.

Lack of earth.

brianmoooore · 2024-12-11T14:52:48+0000

James said:
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 · 2024-12-11T17:47:52+0000

brianmoooore said:
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.