MCB off - can't locate fault

[Simon321456]

Morning

Came downstairs and socket circuit is off. Everything else ok

The MCB switch is off, and there is no play in it at all. By that I mean it won't go back up to the ON position. Its the first time it's happened in this house (bought last year) so I don't know if this is what is supposed to happen but it won't click back to on like the others do. Is this how its supposed to work? I'm obviously new to this!

I've unplugged everything, switched all sockets off and switched all spurs off

It still won't switch back on

I do have some outside lights that are plugged in via a transformer to a switched spur, I've taken the fuse out of that though and still nothing


First question is do I need to have the electricity off to switch it back on? I didn't think I did

Second is that if I've turned everything off that is on the circuit and the MCB won't switch back on; what if anything can I do now?

It's a Sunday so don't want to get anyone out, plus I ran an extension from the kitchen for the router so its not the end of the world if it's not sorted until tomorrow

Is there anything else I can check though?

 

[AndyPRK]

Post a pic of the consumer unit.

It maybe worth turning the main switch off to see if that helps.

And pushing the switch down further before trying to push up.

 

[bernardgreen]

Some MCBs have to be pushed DOWN before they can be reset by pushing upwards.

Is it definately an MCB and not an RCD ? An RCD will have a test button. an MCD will not.

 

[Simon321456]

Yep no RCD (that I can see!)

The switch doesn't go down any further than it already is. I switched the mains off, and whilst the mains was completely off, the offending MCB still would't go up to the ON position

Picture of the unit as follows:

Untitled

• Simon321456
• 27 Apr 2014
• 1

 

[AndyPRK]

Replacement MCB required then. Quite an old unit.

There could well be a fault though that needs fixing which caused it.

Dangerous that gap with live metal inside.

 

[Simon321456]

Replacement MCB required then. Quite an old unit.

There could well be a fault though that needs fixing which caused it.

Dangerous that gap with live metal inside.

Yep like everything in this *&%^£$ house, it seems to have been done by someone who either doesn't know or doesn't care what they are doing. My first house, certainly been a learning experience!

The box and whole unit is in a boxed off cupboard with a lock on it, do I still need to be concerned about that gap?

Can I replace the MCB myself? Or do I need to find out what caused it to break in the first place?

 

[AndyPRK]

It's probably best to get an electrician in to do some tests on the circuit unless of course you know that an appliance caused it.

You could try an get a replacement off eBay by searching for wylex MCB 30 and looking at pictures.

And with the mains switch off tape up the hole.

 

[AndyPRK]

There are some wylex nb30 type2 on eBay so I would get one or two of them ordered. Not expensive.

Some cheap ones ending in 9 hours

 

[Simon321456]

It's probably best to get an electrician in to do some tests on the circuit unless of course you know that an appliance caused it.

You could try an get a replacement off eBay by searching for wylex MCB 30 and looking at pictures.

And with the mains switch off tape up the hole.

Yeah I don't know why it went, would an appliance break the MCB itself?

Think an electrician is probably the way forward, but re the replacement, is it this I'm looking for? Haven't confirmed exactly, but in terms of the type of thing:

£6 or so?

Will tape up that gap too

Should I also look into replacing the whole CU itself?

 

[AndyPRK]

There are some wylex nb30 type2 on eBay so I would get one or two of them ordered. Not expensive.

Some cheap ones ending in 9 hours

Yeap that's the thing. But you want a 30 not 15.
I saw some for £3 ish.

No doubt an electrician will recommend you a new cu
But for £3 + fault finding get your sockets working again.

Do you have a multimeter ?

 

[PrenticeBoyofDerry]

If you can prove the circuit is dead and the MCB is open, then disconnect the the cable/cables entering the MCB, then see if it will then reset, if not the MCB is faulty, if it does then you need to inspect/test the circuit.
Probably do both if the MCB will not set as something has caused it to jam, and could be down to a fault downstream.

 

[Simon321456]

Nope. Well yes, but I don't know how to use it! Someone gave it to me. It's in Russian I think

I need to buy one though, will see if I can get something today. And then learn how to use it

I can't wait for someone to deliver the MCB from eBay so have found them more expensive but in stock for next day delivery -

http://www.sparkiespares.com/index.php?id_product=1144&controller=product&id_lang=1

Take it these are discontinued so only available used/refurb?

 

[AndyPRK]

Yeah they are an old range.

It could take a while to get an electrician and he could have spares himself

 

[Taylortwocities]

While you are at it, PLEASE get three blanks and fill up that hole. It makes me nervous just looking at it.

That copper bar that you can see is live 230volts.

 

[AndyPRK]

A basic guide to seeing if you have a fault.

1. unplug everything from that socket circuit, and switch off spur units.

2. Set your test meter to the resistance ohms range, e.g 200R or 2K.
When the meter probes are touched together you should get about 0.
When apart it should read 1.

3. Turn the main switch off and remove the CU cover.
Cables/screws by the main switch will still be live so be very careful.

4. locate the red wires above the tripped off mcb, (and with MCB in off position) connect one meter probe to the red wires terminal on the MCB and the other probe to the black wire neutral bar.
A good reading is 1
If its reading a low value then a fault is still present on the circuit.

5. repeat above
locate the red wires above the tripped off mcb, (and with MCB in off position) connect one meter probe to the red wires terminal on the MCB and the other probe to the GREEN EARTH bar.
A good reading is 1
If its reading a low value then a fault is still present on the circuit.


If both readings are 1, then you can replace the MCB and see what happens.