mcb failure

Been to look at a lighting circuit today that tripped the mcb when the guy turned on the kitchen light presuming lamp blown he then reset mcb but still had no power. I found the mcb had failed open circuit. Never had this before - has anyone else? What would you think is the cause? No other problems on circuit or anything just curious. May break open the failed unit and see what has gone inside but was just interested. Its a GE one by the away I would say approx 5-10 years old (inspection labels pen writing has faded/rubbed off/was never there!

had a few. not sure what caused any of them to fail though

I was told a few years ago that an MCB`s lifespan was 3 trips.

Must admit to being somewhat surprised by this, but accepted it (this was 2391 lecturer).

Anybody else heard of it?

KME

I was told a few years ago that an MCB`s lifespan was 3 trips.Must admit to being somewhat surprised by this, but accepted it (this was 2391 lecturer).

Anybody else heard of it?

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Nope.

I've had a few fail open, it happens. Some have just been faulty out of the box, some have been in a while.

I was told a few years ago that an MCB`s lifespan was 3 trips.

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never heard of that. but i guess it would depend on fault current - i.e a fault current near max rating may do damage

had quite a few faulty out the box recently of the mk and wylex variety. most annoying. have to try and hide the fact from the customer their shiny new fuseboard has alrady failed to perform!

I have had this ... So after I had changed it I took it back to the unit , drilled the rivets and took it to bits to see what was up ... And there was nothing electricaly wrong but the latching bit had worn out so wouldn't work at all

Had one or two quite rare to have them fail but it happens. I would imagine it will get more commen with all the gear made abroad now.

Some one once told me they bought a job lot of breakers for china from eBay... Installed loads of them , then one day he had one fail un did it ... And found a bit off copper and a switch ... Upsss no protection at all

here is a pic

Nice

old thread but it happened to me today, fitted cu yesterday everything fine, today they said i forgot to connect the lights,

mcb switched on but no power, took it out checked it with continiuity tester, open circuit, rattled and fliped it a few times worked intermintanlty.

MK b6

old thread but it happened to me today, fitted cu yesterday everything fine, today they said i forgot to connect the lights, mcb switched on but no power, took it out checked it with continiuity tester, open circuit, rattled and fliped it a few times worked intermintanlty.

MK b6

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Yes old thread, but even older problem.

I think this is because we are now left to do quality control for all the companies who make(import) this rubbish.They will argue that its to keep prices down, I would argue that we need confidence in a product, which is why if I get any failure I will move over to a different product.

Yes old thread, but even older problem.I think this is because we are now left to do quality control for all the companies who make(import) this rubbish.They will argue that its to keep prices down, I would argue that we need confidence in a product, which is why if I get any failure I will move over to a different product.

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what do you fit now days

All commercial and industrial first choice is melin gerin, I just love the space for three phase, I started, and still am, a devotee of square D, (same group).

I have lost faith in cheap plastic CU's, and prefer metal clad units for any domestic, I find that if its an uneven wall the plastic Cu's never fit properly.

My only pet hate is CEF's proteus range, cheap nasty rubish, but thats my personal review, oh and that carp I think its called chintz or something.

So my fist choice would be Merlin. followed by Square D, then maybe if I wanted cheap, crabtree, but only if i was after a cheap job.

had quite a few faulty out the box recently of the mk and wylex variety. most annoying. have to try and hide the fact from the customer their shiny new fuseboard has alrady failed to perform!

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I've had the same with MK - only ever fitted 2 MK boards - and a duff MCB in each. I was told it's a chance in a million - nobody else ever has any problems.

Are you sure the MCB had failed?

I was called to fix an MCB that wouldn't reset once. I found it was an old type, where you had to first push it down, then push it up. Some of the old ones when they trip are left in a sort of half way state and won't reset just by pushing them up, until you have first pushed them down.

Just a thought.

All commercial and industrial first choice is melin gerin, I just love the space for three phase, I started, and still am, a devotee of square D, (same group).I have lost faith in cheap plastic CU's, and prefer metal clad units for any domestic, I find that if its an uneven wall the plastic Cu's never fit properly.

My only pet hate is CEF's proteus range, cheap nasty rubish, but thats my personal review, oh and that carp I think its called chintz or something.

So my fist choice would be Merlin. followed by Square D, then maybe if I wanted cheap, crabtree, but only if i was after a cheap job.

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:red card X( X( :red card i use crabtree star breaker in domestic and crabtree load star in commercial, and find the kit to be excellent quality, i have in the past used wylex, prtoeus :coat and protek, and found prtoek to be resonable now as well. imho crabtree isnt a cheap board,

Are you sure the MCB had failed?I was called to fix an MCB that wouldn't reset once. I found it was an old type, where you had to first push it down, then push it up. Some of the old ones when they trip are left in a sort of half way state and won't reset just by pushing them up, until you have first pushed them down.

Just a thought.

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Good point.

I forgot about those, they are still about I think most of the old MEM are like that and some old crabtree.

Just put in an MK consumer unit - 16A MCB faulty out of the box. This is the second time recently with MK.

Have had several Hager 6amp not able to be reset after lamp failure trip.

Seems it will do its job but not survive the experiance