Electric circuit breaker trips but resets ok, then trips

I had similar.

No fault on the circuit, it was due to a worn out RCB.

Have a look on Screwfix for a similar one.

Pretty straight forward to swop out for a new one.

Ace, thank you. I will head to Screwfix on the way home.

Ace, thank you. I will head to Screwfix on the way home.

Please don't.

You haven't specified whether it's an RCD, MCB, or RCBO that's tripping, and that makes it clear that you don't know enough to safely swap the part. It might be a faulty breaker, or it might be tripping because of a fault in your heating system. At best you're wasting money, at worst you run the risk of introducing new faults.

Take a photo first.. They come in quite a few shapes and sizes depending on the make /model of fuse box.

And goes without saying... Turn the electric off fully and still treat it like it's live... A shock from a live bus bar is instant death!

Sounds like you've isolated the fault - that's where your attention needs to be.  Main causes of trips in our house have been actual wall sockets failing or items attached to it, like a plug breaking. It's a right pain to find the cause some times.

I had a an issue last year.. Light circuit kept tripping.. Had to call the sparkies...

End result... They said it could take a couple of days Labour to find a tiny fault or, as the wiring was ancient and brittle it would be better to just do a full re wire... 5 grand later an my upstairs lights work again lol.. Dunno if I was 'had' but some of the wiring was shonky as hell even to my eye... So I don't feel too bad about it and I'm 'up to code' now.

Is it a immersion on a tank that switch controls ?

I had this at the last house. Fortunately I managed to drag the sparky who helped build it out of retirement. "Aye lad, I bet I know what's causing that". The 20 yr old exterior PIR under the pergola was randomly filling up with water, tripping the downstairs lights, draining/drying out then working fine for weeks. They don't call it electrickey for no reason.

We have a fused switch in the airing cupboard that switches on/off the water/heating

If there's a heating element or pump, for example, it's just as likely to be a fault with water/electrickery in the cupboard. Get someone to have a look

From your poor description of it, I agree with some of the above answers, in that it is probably a fault with your immersion heater. They usually corrode internally , and can still sometimes work sort of OKish if you havent got that circuit protected by a RCD, or, they just fail, with a direct fault to earth. The element corrodes, and lets water in to give a fault from live to earth. There is no clue on the surface that it is faulty, you need an insulation tester to check it, along with a low ohms meter reading to check the element.

Had similar a few months ago. Nailed it down to one wall socket which turned out to have a poor connection.

Tightened it up and all good since.

..Is it your tumbly on the extension lead in the utility room?

We had similar, tracked it down to our fridge freezer. It was tripping the breaker when the compressor started. Which is why it seemed to be at random.

My 1st reaction whilst scrolling down  was 'do you have an immersion heater?' . Like several others have said.   If so that's going to be my 1st port of call, as the ceramic powder inside the heater element that provides the insulation, can lose its flashover resistance for various reasons (they are constructed with a coiled tungsten wire  stretched though a copper pipe then filled with a ceramic powder, then vibrated to compact, then swaged to a thinner diameter to compact further.  Then put in ovens to dry out any moisture, and the ends sealed up.

(I worked at a place as a development engineer making them for companies like Triton etc 30-35 years ago)

No risk of death tonight, still at work in London and then a drive home?

The switch that trips is EATON AD32B B32 6000 3 Circuit Breaker.

The immersion is fine and not connected to the other circuit. Its the boiler and heater that the trip happens when turned on. There is a white box below the fused switch. It has a green light at the top and two light below for heating and water. When this is on the  boiler downstairs is on, and the hive box on the wall downstairs works. Pictures tomorrow

Apologies for the rough description.

Same, been going on for years, sometimes months between trips, sometime a couple of hours, spent so long unplugging suspect appliances and replacing wall sockets I don't like to think about it. Until it starts happening more 'reliably' I can't get an electrician to look into it, and it's not annoying enough for the £5K rewire so a UPS or two on the router and monitors and we're all fine..

If that’s the unit that is tripping it’s a 32a Mcb which means a dead short fault is happening on the circuit, which won’t be occurring on anything connected to the fused spur as that will have a max 13a fuse in it, unless you’ve jammed a nail in it instead!

As always many thanks for all the input for my request.

This week has been mental with working late and being away on training course. But the silver lining was that I did not do anything destructive to the house.

We had an electrical awning, replacement was a wind it yourself unit, power unit was disconnected and the cable left in a grey IP box that you cant see from the ground.

Wife suddenly remembered asking for the cable to left ready for the if she wanted another electric awning.

Its cracked, leaks an has a bit of water in it. No idea why it randomly tripped though.

The bit above about the old PIR made me look around the house. Been away today with everything left on and its still on.

No idea why it randomly tripped though.

Because it's cracked, leaks and has a bit of water in it? (-:

???