RCD trips when switching lights off

[pdcelec]

I've got a masters degree in electronics

but that has no relevance to the problem you have

and my father-in-law is an electrical engineer with 40 years experience

but does he have any experience in this type of work

and we still can't get to the bottom of this !!

If two people of such hich calibre cannot solve it, how can people replying from a forum possibly stand a chance!. I suggest you contact a local electrician (or are sparks too low for you?)

 

[JonS]

Change of RCD made no difference.

If it is noise, and this really must be the only explanation left, how can I stop this noise from causing an imbalance?

Cheers

 

[pdcelec]

Have you measured the current leakage through the main earth cable?

Are all connections tight? a loose connection (or a wire terminated onto the plastic instead of the copper, very popular fault but difficult to locate). This would explain the intermittent bit, since as the cables gets warmer, then contracts, you will lose some of its conductivity for a while.

Have you conducted RCD tests? and what were the results?

What were your Ze and Zs readings?

Could it be the freezer causing the problem?

 

[JonS]

Tried new RCD but no change.

The noise from switching, whether a light switch or an appliance should not in normal circumstances induce an imbalance that would trip an RCD.

Given all the tests detailed above, the only remaining possible cause of the problem has to be an over sensitivity to switching noise as a result of outside factors like possible 'dirty' mains.

Does anyone know of an approved method of filtering this switching noise?

 

[pdcelec]

Why?

 

[pdcelec]

ALL ring mains and lighting circuits have been confirmed seperate and confrim to current IEE regs.

As my previous question. What were the readings?

 

[securespark]

Yeah, I'm with pdc here. You need to test the RCD to see what level of current it is tripping at.

It's a bit hit and miss, but you could try disconnecting circuits one by one to see if the tripping problem disappears. At least then you could pinpoint it to one specific circuit.

Also may be worth checking plug tops - if n & e are reversed, you can get some very strange happenings re RCD.