MCBs tripping randomly?

[Lewis Curle]

Hi all,

So I’ve been having a strange fault in my house which has just appeared over the past few days. About a month ago I moved my pc set up into the sun house to make space for my second kid.

Inside the sun house/garage I have a DB that is fed of a 40A type B breaker fed by a 6mm core cable.( it’s not a SWA it’s a wierd cable with loads of little cables as a neutral) but I have insulation resistance tested that feed cable and it’s all good. On the garage DB I have a 32A ring main and a 6a lighting circuit. I have had my pc setup in there for a few weeks now and it’s been totally fine up until a few days ago when the 40A MCB is tripping of at random times. It can go off when I’m there and gaming or off through the day when I’m at work.

The circuits in the garage have all tested out totally fine and the feed cable going to the garage DB has tested out fine as well. But for some reason the 40A MCB in my board keeps tripping off. I have changed the MCB as of yesterday and it has went off again today whilst I was at work. There is nothing on in the sun house when the MCB trips. 40A is huge MCB for a house and I can’t get my head round what is causing it because there isn’t even anything above 10A going through that circuit.

Now this would be fine if it was just this circuit going off. As I could slowly work my way through what is wrong with it. But over the past 4 days as well as my garage MCB tripping I’ve had both upstairs and downstairs rings trip off, and as of today the upstairs lights have also tripped off.

They sometimes trip at the same time as the garage but they have tripped off just by themselves. I have tested all the rings and they appear to have no issues with the cables.

What makes it even more confusing is I have a split RCD DB, not once has the RCDs ever tripped on either side. But I have had the garage MCB trip on the left RCD and lights on the right RCD trip at the same time. This has also happened with the ring mains in the house.

I can’t get my head around how a single circuit on its own like the garage can appear to have an effect on another single circuit that are on separate RCDs.

Could it be an issue with the DB itself? Because as far as I can tell after testing each cable they haven’t got any issues. The MCBs can stay on for hours and just trip off.

Any help into this would be great as I’ve been pulling my hair out for days now.

Thanks, Lewis

 

[nicebutdim]

The statistical probability of both old and new MCBs exhibiting the same inexplicable fault isn't worth considering, so there's either a rational explanation, human intervention or this thread is destined to enter rather exclusive territory.

 

[Lewis Curle]

Could you post a photo of the consumer unit with the front off

All the photos I’ve took are too big to upload to this site, not sure how else to to show you.

 

[DPG]

All the photos I’ve took are too big to upload to this site, not sure how else to to show you.

Try taking a screenshot of the photos and also crop them a bit if there's any excess around the edges.

 

[Lewis Curle]

The statistical probability of both old and new MCBs exhibiting the same inexplicable fault isn't worth considering, so there's either a rational explanation, human intervention or this thread is destined to enter rather exclusive territory.

Try taking a screenshot of the photos and also crop them a bit if there's any excess around the edges.

 

[DPG]

My money is on human intervention rather than anything electrical.

 

[brianmoooore]

Haven't looked inside of one for a while, but I take it electronics hasn't found its way into MCBs yet, making them possibly vulnerable to so called smart meters.

 

[Lewis Curle]

My money is on human intervention rather than anything electrical.

Haven't looked inside of one for a while, but I take it electronics hasn't found its way into MCBs yet, making them possibly vulnerable to so called smart meters.

We do have a smart meter plugged in, in the kitchen which is the downstairs ring. I’ve had that unplugged though multiple times when trying different things.

There is only me and my partner in the house and neither of us are doing it in purpose.

 

[brianmoooore]

The mechanism inside any MCB that I've dismantled to date is fairly simple, and, if the MCB is in working order, there is no possible way it can be 'tripped', other than by doing what it's supposed to (which it's not, if no outgoing cable is connected), or perhaps by a mechanical shock, such as hitting the side of the fuse box with a hammer.

 

[nicebutdim]

Any electrical explanation is far beyond my comprehension, but I desperately want to see this thread resolved - especially now the same fault has manifested itself in the same breaker in a brand new board and with no load connected.

 

[James]

Just to confirm.

the original summer house was experiencing random trips
it was fed from a normal mcb

the board has been changed and the same thing is happening with the new equipment

the outgoing live cable has been removed from the circuit breaker and the breaker still trips at random times.

if all the above is correct, i would be looking for a mechanical reason for tripping as mentioned above by @DPG

I would be considering a covert ip camera watching the board with the cover off and seeing what is going on.

edit,
A video of a breaker tripping on its own with no outgoing cable attached would really amaze me.
if that happens, i would be recommending posting on a forum that follows ley lines, ghosts, spirits, extra-terrestrials, EMF and grounding, etc.

 

[timhoward]

In spite of the anticipated reaction and assurances I think a little experiment is due to disprove human interaction before wasting more time on this .

Buy another Wylex B32 MCB (3 or 4 quid)
Swap the B40 for a B32. Don't say a word to anyone but move the sockets on the right to the new B32 on the left (along with the respective neutrals) and connect the summer house to the empty B32 on the right (and move the neutral too). This is all temporary.
See if the the same breaker keeps tripping.

If the problem moves to the right without anyone else knowing then it's an electrical problem that is foxing the finest electricians I know.
If the problem stays on the left I'm afraid it's most likely to be a human interaction issue.

 

[Lewis Curle]

Just to confirm.

the original summer house was experiencing random trips
it was fed from a normal mcb

the board has been changed and the same thing is happening with the new equipment

the outgoing live cable has been removed from the circuit breaker and the breaker still trips at random times.

if all the above is correct, i would be looking for a mechanical reason for tripping as mentioned above by @DPG

I would be considering a covert ip camera watching the board with the cover off and seeing what is going on.

edit,
A video of a breaker tripping on its own with no outgoing cable attached would really amaze me.
if that happens, i would be recommending posting on a forum that follows ley lines, ghosts, spirits, extra-terrestrials, EMF and grounding, etc.

I’ll try and get a video on Saturday when I have time, speak to you all then and thanks for your time!

 

[Lewis Curle]

In spite of the anticipated reaction and assurances I think a little experiment is due to disprove human interaction before wasting more time on this .

Buy another Wylex B32 MCB (3 or 4 quid)
Swap the B40 for a B32. Don't say a word to anyone but move the sockets on the right to the new B32 on the left (along with the respective neutrals) and connect the summer house to the empty B32 on the right (and move the neutral too). This is all temporary.
See if the the same breaker keeps tripping.

If the problem moves to the right without anyone else knowing then it's an electrical problem that is foxing the finest electricians I know.
If the problem stays on the left I'm afraid it's most likely to be a human interaction issue.

I’ll also try this

 

[James]

I’ll try and get a video on Saturday when I have time, speak to you all then and thanks for your time!

You have such an unusual fault, there are a dozen highly trained and experienced electricians here that are invested in your problem and would love to find out what the problem is.
Mystery hunters should be a new member tag for all that have posted there ideas here!!
Our time is given freely but thankyou for recognising it.

 

[mainline]

Remove the mcb and lock it away for a few days, bet it hasn't tripped in that time.