Switching OFF bathroom lights trips the RCD

[EFLImpudence]

Heh, yes okay 'transformer' may not be accurate, its just whats written on the box.

It's a forum joke. Someone else, not you.

 

[ban-all-sheds]

I'm sure we all found the exchange amusing.

Well - almost all - maybe SimonH2 will show consistency and criticise you all for making inappropriate comments.

 

[KevDIY]

It's a forum joke. Someone else, not you.

Ah, thanks, that makes more sense now

Though I can see the point behind it; my theory may not have much basis.

Cheers
Kev

 

[JohnW2]

Though I can see the point behind it; my theory may not have much basis.

As I wrote before, one usually has to struggle to find rational explanations for these events. The problem obviously is that one a circuit has been broken, by switching it off, even if there are back-emfs, transient voltages due to switching to., there is no obvious path through which for current to flow even through both sides of the RCD, let alone more through one side of the RCD than the other (which is what is required for it to trip). For that reasons, most of the theories have to hypothesise capacitive coupling (to earth or some other circuit) from one of the conductors of the circuit's cable.

Kind Regards, John

 

[bernardgreen]

The original RCD was non electronic and required the sensor to provide the energy to operate the trip mechanism. The electronic RCD does not require that amount of energy from the sensor, an amplifier takes a minute amount of signal from the sensor, amplifies it and this provides the energy to operate the trip.

it is not impossible that a large but transient and harmless un-balance lasting a few micro seconds could over drive the amplifier and cause it to operate the trip.

Transient voltage spikes passing through stray capacity between conductors does create transient unbalances that are harmless but do seem to be responsible for false tripping of RCDs.

These transients could ( should ) be filtered out but adding ( more ) filter components would add cost and the risk of component failure preventing the RCD tripping would increase with the additional components.

 

[KevDIY]

Thanks both, thats helpful. I may not know the specific cause, but it helps to know some potential mechanisms for it - so it may not be mysterious little gremlins at work then

Cheers
Kev