MCBs tripping randomly?

[yorkieone]

When you say passed an IR test do you mean they had a perfect >999megohm or a just scraped through at 1megohm?



A 40A MCB and a 16A MCB will not discriminate on a fault, it is pretty much pot luck which one will trip first.

1 meg ohm at 500v is ok we would like infinity but it's not an insulation fault

 

[Lewis Curle]

Lewis Curle: have you been able to investigate this problem further to your last message?

Long time no speak everyone, so after a busy few months with the new baby I’m back to trying to figure this fault out. I’ve not been standing idle, I have tried multiple things to try and figure out this bizarre issue.

Short story of it all is I have changed the whole consumer unit in my house for a brand new Wylex one. It’s a split RCD board. First thing I did after changing it was of course test the thing. The issue is still exactly the same after about half an hour of being in the sun house gaming away the sun house MCB tripped along with the upstairs ring and the smoke alarms. Smoke alarms have never tripped before but the upstairs ring has. This was the only time since the new board that those other MCBs have tripped.

So naturally I started to break down the sun house in stages again, I disconnected everything out of the garage DB and the MCB still tripped sometime when I was at work the next day. So i then disconnected the cable feeding that garage DB and taped the ends up and put them safely out of the way of anything. The MCB still tripped. So then I disconnected the the cable at the house db end. And some how the 40A MCB with nothing in it has tripped three times in the past three days. So the sun house has nothing to do with this strange fault in my eyes.

Now I can’t workout how that MCB is still tripping with nothing connected into the thing. The only thing that hasn’t been changed now is the cable that is feeding my DB from the meter box. Nothing has showed up on testing that cable, it has been properly tested and all the results came back perfectly. So now I don’t really have a clue on what to try, other than changing that cable which would be a nightmare to change.

As an electrician I can’t make any sense of it.

I’ve has the grid people out and they have checked the cable into my house and inside the meter box and found nothing wrong.

Now thinking back to the times that it trips and the times that it doesn’t, things inside the house are being used. It doesn’t seem to matter what is being used but it trips a lot more often when my partner is cooking or watching tv downstairs.

I’ve not managed to keep it on for more than an hour when she is kicking about in the house using things. I also would like to say that it is not being intentionally turned off, someone asked that once and I just want to make it clear now!

So thanks for reading, I will attach some photos of the DB and the meter box.

Lewis

 

[brianmoooore]

What is tripping? MCB or RCD?
It's a pity you didn't fit a RCBO board.

 

[Lewis Curle]

I can’t upload the photos they are to big

 

[Lewis Curle]

What is tripping? MCB or RCD?
It's a pity you didn't fit a RCBO board.

The 40A MCB that was feeding the sun house is the main on that’s tripping. Although it’s tripping without the cable in it right now.

 

[DPG]

The 40A MCB that was feeding the sun house is the main on that’s tripping. Although it’s tripping without the cable in it right now.

The 40A MCB is tripping without anything connected to it??

 

[Lewis Curle]

The 40A MCB is tripping without anything connected to it??

Yeah consistently for the past three days

 

[DPG]

Yeah consistently for the past three days

Literally no cable in the output terminal?

 

[Lewis Curle]

Literally no cable in the output terminal?

Literally it’s connected to the busbar and they is nothing coming out of the top side. It’s tripped three times in the past three days. I can’t make any sense of it. Bear in mind it’s a brand new MCB as well.

 

[DPG]

Literally it’s connected to the busbar and they is nothing coming out of the top side. It’s tripped three times in the past three days. I can’t make any sense of it. Bear in mind it’s a brand new MCB as well.

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

 

[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.