Dual RCB CU, RCB trips but MCB is not tripping.

[EFLImpudence]

I thought I read from above that turning on the main switch may not isolate everything?

It definitely won't - perhaps you forgot to write off.

If I read wrong the big left red switch on the CU picture is the main switch for this CU.

Perhaps you forgot to write right.

Is that enough to isolate everything?

Is what enough? Perhaps you forgot to tell us what you're going to do.

Also that big black fuse is a cut out fuse.

As above - more memory loss.

I agree with John D v2.0. This is all nonsense.

 

[platforminc]

It definitely won't - perhaps you forgot to write off.


Perhaps you forgot to write right.


Is what enough? Perhaps you forgot to tell us what you're going to do.


As above - more memory loss.

I agree with John D v2.0. This is all nonsense.

Not sure what you mean here. If you look at the last pic you will see where I have turned off the breakers/MCB, but since I got told that's no good, its all about finding time to open the CU and disconnect the live and neutral, which I will do and report back here.

Thanks.

 

[JohnW2]

It definitely won't - perhaps you forgot to write off. ... Perhaps you forgot to write right.

Whilst he presumably typed "on" when he meant to type "off" (and which of us has never done things like that?!), the Main Switch surely is the left-most device in the CU, isn't it?

... Is what enough? Perhaps you forgot to tell us what you're going to do.

Or perhaps you forgot to read what he told us?

The OP wants to completely disconnect circuits, one at a time, by switching off the MCB and removing neutral from the neutral bar (and, hopefully, 'parking' it in something) in an attempt to identify the circuit which is causing the RCD trips. I questioned whether it was appropriate for him to do things within the CU, warning him that some live parts would remain even with the main switch open. In his post to which you are responding, he was seemingly again seeking clarification as to whether switching off (he typed "on") the main switch "is enough to isolate everything".

The continuing questions certain reinforce my concerns as to whether he should be opening the CU at all.

Kind Regards, John

 

[platforminc]

Hi All.

I opened the CU and disconnected the drive over lights for a week, the next week disconnected the garden lights. The issue has not occurred, not surprised TBH as it has been dry for almost 3 weeks now with no drop of rain.

I will leave it disconnected till it next rains.

Thanks all.

 

[platforminc]

Hi All.


I have not posted any updates here as it has not rained for some months now until, last week and below is a sumary of what happened.

The garden lights were disconnected from the CU.
Since my last post, the drive over lights were my main suspects but they have been on since after it had rained and tey still kept coming on, I even sprayed it with a hose to see if they would trip etc.


On the 28th of July, which was last Saturday I knew the forcast said it would rain, so what I did was to connect up the garden light back to the CU in order to test it, since it would rain the next day. So I connected it. On the 29th of July it rained a lot and hold and behold the CU RCB on the other half tripped. So it looks like its a set of 4 lights. Now, these lights are as pictured three are up and down lights, and on a wall that is not straight/flat, what I did a few months ago was to use clear silicone to seal all around the edges where the up/down meets the wall, the idea was to seal it and ensure that there is no moisture or water ingress. So i did this for light 1,3 and 4.

What should I do now ?

 

[aptsys]

The junction box is probably suspect, given there is a gland on the top side of it. The other suspect would be the dodgy PIR floodlight, but you'll only know by opening up and inspecting all of the fittings.

I'd remove the silicone that you've added. The lights are designed so that any water can drain out without affecting the electrical behaviour. By sealing them up, they'll probably end up filling with water over time.