Upstairs light circuit all down - MCB not tripped

[bernardgreen]

With regards to the MCB... It does trip when turned on... But NOT instantly. Takes between 8 and 10 minutes roughly which I find strange.

It is strange,

An MCB trips when there is too much current flowing. A broken wire prevents current flowing. The exception to that is when the broken end shorts to another bare wire but then the current flowing will be high enough the trip the MCB almost immediately.

It might be that as you walk around looking for the fault you stand on a floor board under which is a damaged cable. Your weight squeezes the cable pressing damaged ( bare) conductors together causing a short circuit which trips the MCB. The damage may include a broken Neutral which would explain the voltages you are finding.

 

[azibux1]

It is strange,

An MCB trips when there is too much current flowing. A broken wire prevents current flowing. The exception to that is when the broken end shorts to another bare wire but then the current flowing will be high enough the trip the MCB almost immediately.

It might be that as you walk around looking for the fault you stand on a floor board under which is a damaged cable. Your weight squeezes the cable pressing damaged ( bare) conductors together causing a short circuit which trips the MCB. The damage may include a broken Neutral which would explain the voltages you are finding.

Thanks for that

Will check out the voltages properly later (as I had the meter set wrong)

I don't think it is anything under the floorboards though as it has happened while we were in various places of the house (one of which was standing next to the consumer unit)

 

[Taylortwocities]

Will check out the voltages properly later (as I had the meter set wrong)

Before you start. Set the meter correctly and make sure that it still can read a mains voltage.

Some meters, and their test leads, have fuses in them that can blow if you do something stupid (like connect the meter across a live voltage when it is set to the amps range).

If you start off with a faulty meter then you'll be chasing your tail all day, and its too hot for that.

 

[azibux1]

Before you start. Set the meter correctly and make sure that it still can read a mains voltage.

Some meters, and their test leads, have fuses in them that can blow if you do something stupid (like connect the meter across a live voltage when it is set to the amps range).

If you start off with a faulty meter then you'll be chasing your tail all day, and its too hot for that.

Certainly too hot, was cooking in the loft yesterday even in the evening.

Will check the meter is getting a proper 230v reading from a socket I know works before going up there.

Thanks

By the way... Are the fuses replaceable or is it new meter time then? Hopefully doesn't come to that though

 

[EAST61]

Bit dubious of this electrician who turns up every now and then but never long enough to solve what should be a straightforward problem.

 

[bernardgreen]

was cooking in the loft yesterday

a kitchen in the loft ? that must be for Haute cuisine ( sorry )

 

[azibux1]

Bit dubious of this electrician who turns up every now and then but never long enough to solve what should be a straightforward problem.

He's a friend who has only turned up once - as a favour squeezed in before visiting another customer (hence the lack of time)

He is happy to come back Wednesday and that will probably be what we do if we can't crack it tonight

a kitchen in the loft ? that must be for Haute cuisine ( sorry )

Ha

 

[Taylortwocities]

Are the fuses replaceable or is it new meter time then?

Just check it works properly and worry about it if it doesn't.
A proper electrician's meter will have replaceable fuses in the probes. I don't know what you have?

 

[azibux1]

Just check it works properly and worry about it if it doesn't.
A proper electrician's meter will have replaceable fuses in the probes. I don't know what you have?

Fair enough. It's nothing special, couldn't justify the money for a Fluke or anything similar based on the amount I'd use it (that's what I'd call a proper electrician's meter lol)

I just have this

https://www.amazon.co.uk/gp/product/B000ELJ0G0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[securespark]

With tungsten filament lamps in circuit and switches closed, if the neutral is broken it will become live downstream of the break.

If the break is between the supply and the first lamp, that would explain why no lamps light. There is the possibility that there is more than one fault in more than one location....

 

[azibux1]

With tungsten filament lamps in circuit and switches closed, if the neutral is broken it will become live downstream of the break.

If the break is between the supply and the first lamp, that would explain why no lamps light. There is the possibility that there is more than one fault in more than one location....

It is possible, hopefully not the case though as that doesn't sound easy to track down lol

Also just a bit of info... the bathroom lights (that flickered) do NOT appear to be the first in the circuit. They have too many wires coming in and out of the junction box for that. 5, which I count as:

1 - in from previous light
2 - out to next light
3 - out to string of 6 downlights for the bathroom
4 - pull string switch
5 - extractor fan

Gonna see if another electrician can come out tomorrow Let the pro see what they find. I think I'm done / not going to find this with my skills unfortunately. Will be much quicker for the electrician

 

[securespark]

Could just as easily be the first in the circuit couldn't it?

If there are "in" and "out" cables it could be anywhere on the circuit but last.

 

[azibux1]

Could just as easily be the first in the circuit couldn't it?

If there are "in" and "out" cables it could be anywhere on the circuit but last.

True.. I overlooked that obviously

Logically (based on distance) it should not be the first however

 

[securespark]

However, if you have examined this junction box closely. remade the connections in a sound manner and verified voltages between conductors as normal, then the problem is very unlikely to be here.

If the voltages are not normal but the connections sound, then the problem is deffo elsewhere.

 

[deadshort]

You certainly can be accused of not trying ! Have you had any building work done or put shelves up recently? I had a call out to a fault which turned out to be screw through a cable holding down a carpet threshold strip ! It took ages to find

DS