Fusebox - loose connection on busbar and mcb

[Lectrician]

Some one fitted a a breaker in thebord which didn't quite fit, and I assume the MCB terminals were a little out of line, and so the new breaker didn't bite well to the busbar.

There was no fire - just serious overheating of the first MCB (orange switch), and this heat was transfered down the copper busbar to the others.

 

[securespark]

The other possibilty is excess load.

What size is the shower?

 

[JohnD]

I think Lectrician put his finger on it.

That non-matching MCB would not have been fitted when the house was built, it's a later add-on.

Maybe we ought to have some rules about inspection and certification of new circuits, especially for bathrooms and showers

 

[mogthefrog]

Oh. Yes the old shower mcb was orange wasnt it? That was there when I moved in. Maybe previous tenant cut a few corners and placed a mismatched one in.
Now all the mcbs match.
I will still get the busbar issue seen to, but my concern is whether the flat and ourselves are in any danger if the overheatin problem occurs again.

 

[JohnD]

Unlikely.

But a good idea to take combustibles away from the CU, and have a smoke alarm nearby.

 

[mogthefrog]

Thanks for this John D
The CU is above the front door in our flat. There are shoes on the floor because that is where people generally leave them, adn there is a smoke alarm fitted there. There is nothing directly next to the CU that could catch fire. Is this what you meant by surrounding the CU?

 

[JohnD]

I really meant directly above it (as the hot air and smoke will rise). A plaster ceiling is pretty fireproof.

Or beside it (just in case)

Or under it (in case a hot bit fell out of the bottom).

You could avoid all of these by not having shelves or cupboards adjacent to it. 300mm should be plenty.

All of these are very unlikely to happen, though. As you have seen from your previous experience, even though the busbar got hot enough to burn away the bottom of the MCB, the heat was contained within the enclosure, and there is just a small distortion of the front cover under the bad MCB.

The design is that overheating will be contained within the enclosure. Bad contacts will eventually burn away so they then stop overheating (this is common in Shower switches).

I expect your CU is fitted to a plastered wall, which again is fireproof. Some older people like to fit then to a backing board; either MDF or chipboard (which is difficult to set alight) or, my preference, laminated board as used in kitchens (the melamine surface will not support a flame).
I have to confess that i have some cardboard boxes stacked next to my own in the garage but also a smoke detector on the ceiling wired to the house.

 

[mogthefrog]

Thanks again John D
There are no shelves adjacent to the CU, the only thing below is carpet, which could be flammable!
What I may do is order a busbar myself depending on cost, then int ehnext few weeks get a quote on getting it fitted. Money is an issue so not sure if I want to get a whole new CU unless safety depends on it.
Your advice is of great help John D so many thanks for taking the time out to give it!