MCB?

[shdhavboughtanewhouse]

All the overhead lights in one part of the house have gone out. We have reset the main trip but are unable to reset the mcb for the bit where there are now no lights. Can we change the mcb or do we hve to get a man who can?

 

[RF Lighting]

Will the MCB reset whilst the main switch is off?

Try this, then switch the main switch back on and see if the MCB trips.

Does the MCB flash and go bang or pop when you try to reset it?

 

[shdhavboughtanewhouse]

We've tried that just now but there is no resistance at all in the offending mcb.

 

[RF Lighting]

Can you see a make or model number on you CU or MCB?

How confident are you at working with electricity?

 

[shdhavboughtanewhouse]

Can you see a make or model number on you CU or MCB?

How confident are you at working with electricity?

It says

Hager
B6 6000
230/400 v~ 3
MT 106 450106 7

The boss is pretty competant!

 

[RF Lighting]

You can buy a replacement from here.

http://www.tlc-direct.co.uk/Products/HGMT106.html

 

[shdhavboughtanewhouse]

You can buy a replacement from here.

http://www.tlc-direct.co.uk/Products/HGMT106.html

Thanks, will do. I assume I switch the main switch off, take the cover off disconnect and replace the mcb.

 

[Taylortwocities]

Correct.

If you have another 6A cb in the consumer unit you could first swap over the live wires from the faulty circuit. That will confirm if it is the CB that is duff or if you still have a fault on the circuit.

Turn main switch off before removing cover. etc

TTC

 

[Steve]

isolate elsewhere if you can. there may be a main switch somewhere between this consumer unit and the meter.

If not beware the main tails into this unit are still live.

 

[kai]

Where a Breaker has had to interrupt a current greater than its Breaking Capacity, it tends to do that, when it's impossible to flick the breaker back on, as a safety mechanism indicates that it has been damaged beyond repair.

It's time to get your wallet out, and pop down to B&Q etc, to buy a new one.

 

[JohnD]

Where a Breaker has had to interrupt a current greater than its Breaking Capacity, ....

You mean, more than 6,000A

 

[plugwash]

iirc breakers typically have two breaking capacities, the maximum they can safely break *once* and the maximum they can safely break repeatedly.

 

[ricicle]

You beat me to it JohnD.Any MCB that is trying to break a current in excess of its breaking capacity is going to end up a molten lump or self destruct .Hope the service fuse reacts quick enough

 

[industryspark]

but are fault currents that are 6KA or even 10KA (some breakers rated to this) common in domestic installs?

work in industry so dont encounter much domestic stuff on a day to day, but from what ive seen the fault current has always been very low?

suppose it depends if the substations in your back garden really!

 

[JohnD]

I calculated the PFC at my house to be 10.1kA, but this is using estimated figures and as I am at the end of a road, nowhere near the substation, I am sure this is an overestimate. It would be at the meter, anyway, not on a final circuit.

All my RCBOs are 10kA anyway