MCB Tripping

[Adam09]

Hi guys,
I have an MCB that keeps tripping, and I have no idea whatsoever on what is causing this. I have been around the house checked if the sockets & lights are on, and all are fine. We have no wired smoke alarms, and the house alarm still has supply, as well as the porch light.

I just can’t find what this MCB is for, let alone why it’s tripping?

How do I go about finding out what this is wired to? Could I remove the front panel off of the consumer unit and see what thickness wire is connected to this to identify what type of circuit this will be?

The MCB is a Hager b16.

Any help will be appreciated!

Cheers, Adam.

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• Adam09
• 17 May 2009
• 1

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• Adam09
• 17 May 2009
• 1

 

[securespark]

Leave it off for a few days & see if you're missing anything.

If you feel competent, open the CU (wear gloves & switch off first) and you could check the colour, type & thickness of cable & maybe start to trace it to see where it goes.

 

[londonboy]

Possibly an immersion heater?

 

[Jaymack]

You'll probably find out soon what it is supplying if you leave the MCB off.
It is a dangerous situation to repeatedly reclose an MCB as you will appreciate, an experienced electrician with a circuit tracer would be of benefit, this would involve switching off all the power excepting the faulty one. 16A could be an immersion heater circuit.

Regards

 

[Spark123]

Something outside in the wet?

 

[ColJack]

my money's on it being the immersion heater..

 

[securespark]

Outside

Immersion

Outside

Immersion

Let's call the whole thing off!

 

[Adam09]

Hi guys, thanks for the replies.

I don’t have anything electrical wired up outside, so it’s definitely nothing getting wet. I have a Combi boiler, so it’s not an immersion causing this problem.

I put the MCB back on, and checked a few hours later to find that it had tripped yet again.

This has only started happening recently, and the only thing electrical that has being changed was wall lights being disconnected in the lounge. This MCB was definitely not tripping before this, but when it is tripped nothing around the house is off, so who knows how long it had being tripped for.

Stupid question, but is it a STRICT NO to removing the front cover off of the consumer unit whilst the main switch is on? I’m not going to be poking my fingers around in there or anything, just want to see size of cable etc.


Also, quick question, we had the kitchen refitted last year, and had the cooker wired in and the ring main extended. Recently there has being a very 'fishy' smell in the cupboard that has the main cooker switch in. I have searched the forums, and see that this is often caused by melting plastic, sockets and wires. Should I check all connections behind socket plates etc?

Thanks for the help, much appricheated.

 

[rebuke]

If you don't know what it's for, then I'd suggest leaving it off. Go round and check that all the subtle things (fridge+freezer etc) are still working just in case, and then just wait - eventually you'll discover something that doesn't work...

 

[Adam09]

Why leave it off though? It has always been on up until this tripping problem. Would it not be best to figure out what’s wired to the MCB?

P.s - about my kitchen cooker socket, I have had the socket on whilst cooking dinner, and the smell is a lot stronger in the cupboard. The switch is metal/chrome, and is slightly warm. I will try replacing this with a new white switch/socket.

Thanks

 

[rebuke]

I suggest leaving it off as you don't know what it is. Imagine for example that at some stage someone has removed an immersion heater, but rather than taking the cable out properly, they just cut it off somewhere. It's now got slightly damp, and hence is tripping occasionally. You wouldn't want to leave a floating cable live, hence keep it off until you figure out what it is.

An idea occurs, although you have a combi now, it's quite likely that it wasn't always one - if you can work out where an old cylinder might have been (e.g. airing cupboard etc), have a look and see if there is a connection point on the wall, as it might be whoever took it out has just left it, and for some reason the connection point is causing it to trip somehow. Another thing to check is that with it tripped, does your combi boiler still work, as it might be someone re-used a circuit to supply the combi (and it isn't something you'd obviously think of as potentially being off while the circuit has tripped)...

 

[mattysupra]

i dont understand why you must keep turning it on when its tripping and showing there is a fault.


Surely its better to leave it off untill you find what is not working rather than finding out what is faulty when it sets on fire or something !

 

[sparkyspike]

Stupid question, but is it a STRICT NO to removing the front cover off of the consumer unit whilst the main switch is on?

Yes. So turn it off before you open the cover! This is usually the first place an electrician wil look, in order to determine the cable size and in which direction it goes. The cable may even be marked.

When you do this, take a photo or two so we can all see.

Don't rule out the lights. I did some work on a house in Islington a fortnight ago where all the lighting circuits were on 16A breakers - using 1.0mm cable.

 

[ColJack]

Yes. So turn it off before you open the cover! This is usually the first place an electrician wil look, in order to determine the cable size and in which direction it goes. The cable may even be marked.

please note that turning off the isolator on the boards does not isolate all live parts inside it.. the incomming cables and terminals of the isolator will still be live..

so keep your screwdrivers and hands off those areas..

 

[Adam09]

Thanks for all the replies!

Removed the cover from the consumer unit this morning, and the cable wired to the MCB is not labelled up, and goes straight through the back of the consumer unit through the wall.

Is there anything I could do to 'trace' the cable? It's almost a month since the MCB has been OFF now, and still haven't noticed anything around the house to not be working.

I would still like to find out what this is for though...

The MCB is a Hager b16.

Pictures attached.

Cheers
-Adam

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• Adam09
• 16 Jun 2009
• 1

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• Adam09
• 16 Jun 2009
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• Adam09
• 16 Jun 2009
• 2

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• Adam09
• 16 Jun 2009
• 1