tripped mcb

Do you need to push it fully down before you reset?

If that dos not work then your fault may be in the wiring and not an appliance.

 

Are you sure everything is disconnected? What ring final is it? is it the upstairs or downstairs or maybe kitchen?

 

If you are sure everything is disconnected then it points to either a wiring issue - some examples could include a nail or screw though a wire that has finally caused a short, wire loose and come out of an accessory, bad/worn insulation ... most of which will need an appropriate competent person to investigate and resolve. You may also have totally overloaded teh MCB and that has, itself, failed - again you need a competent person to investigate.

 

Yup what @Pollowick said.

Either damage to wiring or a faild MCB.

To test you need to isolate all power to the consumer unit circuits. Disconnect the ring final wires from the MCB and Neutral bar and use a meter that has a buzzer feature to test for continuity between the blues and the browns.

The buzzer should sound when testing brown to brown(red to red for old colours) and blue to blue(black to black for old colours)

If you get a buzz from the tester when you test Blue(black) to Brown(red) then you have a short.

If not then test from the Neutrals Blue or Black to the Earth bar(green/yellow) and between Line Brown or red and earth if you get a buzz then you have a short somewhere in your ring final.

You can also test for this from behind a socket outlet.

If you make sure power is off to the sockets, and i do mean double check to make sure. Then remove one of the socket outlets and test for a short as above between the brown and blue(Line and Neutral) then test Line to earth and neutral to earth, there should be no continuity or sound from the testers buzzer.

If you get a buzz then you now know you have a short in the circuit, maybe a nail into the wiring or worst yet a mouse or squirrel has chowed down on your cables so check your loft space.

If all is fine then you can call the MCB has failed and change it but note the MCB screws fastening it to the busbar are very very tight so a standard Philips screwdriver probably wont loosen it. You need a electricians screwdriver that is made specifically for these terminal screws. It mat look like a philips/pozi driver but it is not.

 

Or an easier test, since fire has suggested powering down the entire system anyway. Once you switch off the incomer on the consumer unit. If the tripped MCB still will not reset its failed. #If it does reset then it points to a circuit issue and you should get someone competent in to have a look

 

Phillips definitely not! A decent quality Pozi will do it, the screws were designed in that way, have a very close look and you will see that the "flat slots" have a small indent that matches teh angled slope of a Pozi. As you say, the best way is to use the specific driver, called a 2pt Modulo-Terminal driver, the CK part number is T49145-2

 

MCB or RCD or RCBO, most people cant tell the difference.

 

Whats an MR30 grrrrrr?

 

An Eaton RCD module to convert it to an RCBO

 

So it is an rcbo.

 

Hang on Tiger!

OP sounds like they would not have an idea to safely isolate and go messing about behind a socket outlet let alone test even though you have described how a spark might do it. .

Needs a spark to test and verify TBH

 

Completely agree, although his method wouldn't even be used by an Electrician who would opt for the correct equipment used in the correct way.

So his method actually has no merit whatsoever.

 

Not everyone has a £500++ multifunction tester and they won't be going out to buy one to test their circuit. Those that become dependent and rely on the multifunction tester to test become robots and would be a danger to themselves as well as others. There are many things a comprehensive multifunction tester will tell you is a pass when in fact is a fail, remember that.

Ok i agree with that.

 

What are you talking about? You cannot test insulation resistance with a buzzer which is what you claimed.

 

Insulation resistance?

I never said any such thing, i was clearly explaining how to test for a short and that is certainly not a 500v+ insulation test.

 

If you want to go into the relative science of the capacitive and reactive components of a cable to test for insulation effectiveness and how it works then we can certainly go there but in regard to the OP having his MCB tripping and not being able to turn it on for constantly detecting a fault then it is most likely a short fault.
If not then yes an insulation test is needed. Always cover the basics first then go deeper as needed.

For a DIY person to do preliminary tests is fine, inspect all cables and test for failures with more readily available cheaper equipment, particularly checking for shorts.
For an MCB to trip like this and it be due to insulation failure that only a insulation test can find is very rare indeed.

 

Need to jump in here mate. . .

The 9VDC that powers the little test meter the OP should not be using, is not adequate to detect some faults including shorts. .

The correct test voltage to be used to confirm NO faults exist is under table 61 page 169 of the Big yellow one which that being is 500VDC (that being twice the value of the supply voltage )

I did ask you if you are a practising spark a while ago. .? Y/N

SiFi