Upstairs light circuit all down - MCB not tripped

[EFLImpudence]

Having a look on Google the ones you mentioned both have test switches / buttons? The 'breaker' in question does not have anything other than the toggle / trip switch - I believe it is an MCB

That would appear to be correct.

When I say it is fine - This is because it is tripping - If it was faulty it would not trip at all surely?

I don't know what that means.
An MCB tripping when it shouldn't is faulty as well.
You cannot make an MCB trip other than causing a fault - not wise.

See above regarding the trip.

Where? Where you said it hadn't tripped?

Sorry that was badly worded regarding the switched live - I was trying to say that if all the switches are off (open circuits) and the MCB is no longer tripping then that narrows down the issue somewhat. I see what you are saying though with regards to the other lights - with the MCB in the OK position - even if only momentarily the other lights should be working regardless until it trips.

So you are now saying that the MCB HAS tripped and can only be switched on momentarily - to keep doing that will burn it out.

That negates everything that has been said and now you have to look for a short-circuit or earth-fault.

 

[azibux1]

I will be able to tell for sure when I'm home. Will update then

Didn't realise they can trip unnecessarily.

It is possible surely all what was discussed earlier is still relevant? The potentially loose connection wherever could have been did not caused the MCB to trip if the circuit was just open. But now if it has been disturbed (physically) and is a much worse connection (intermittent and very close to being connected) or shorting out on another connection as opposed to being completely disconnected it may be causing the trip? Or not?

As said, will know more info on the trip when I'm home

EDIT: Without going into the loft, the electrician managed to get a junction box (related to the flickering downlight) down into the bathroom through the cut out - so very well may have disturbed something to change the situation of the loose connection.

 

[ban-all-sheds]

Didn't realise they can trip unnecessarily.

Anything can go wrong.

It is possible surely all what was discussed earlier is still relevant? The potentially loose connection wherever could have been did not caused the MCB to trip if the circuit was just open. But now if it has been disturbed (physically) and is a much worse connection (intermittent and very close to being connected) or shorting out on another connection as opposed to being completely disconnected it may be causing the trip? Or not?

I'm not 100% sure what that means, but...

A loose connection will not cause an MCB to trip.

But if a cable falls out of a terminal, and makes contact with something else then you may well get a fault which causes a trip.

 

[333rocky333]

I think we may have missed this bit


" It did not trip at the time of the lights flashing but I think at some point after that it tripped (or my Dad turned it off). Either way, after that also I put it on to check something - the lights still didn't work and I left it on (so did Dad) - checking it a while later it had tripped - so seems to work OK. What timeframe it is tripping in I'm unsure of, but it is not instant.

It tripped at some point also while the electrician was doing some tests - so seems functional and put to one side for now in the troubleshooting."

 

[azibux1]

A loose connection will not cause an MCB to trip.

But if a cable falls out of a terminal, and makes contact with something else then you may well get a fault which causes a trip.

Thanks for clarifying.

As I say it is possible then that something has been disturbed when the electrician pulled the junction box down for the light.

Will check it out later if the loft is a more bearable temperature by then ha

 

[securespark]

Was it just flicker and then everything died, as pretty much one event, or had it been flickering for a while? Is the circuit on an MCB, or an RCBO?

A sensible comment.

Probably that they aren't getting any power.

Are you being serious? I think he had got to this point.

If that's why you thought it would be a good idea to wire them in parallel then your "fairly competent" has to be challenged.

And so do you. His logic was perfect. Why say this?

 

[azibux1]

A sensible comment.


Are you being serious? I think he had got to this point.


And so do you. His logic was perfect. Why say this?

One downlight flickered, they all then dimmed down and briefly came back on before going out again and none came back since.

MCB.

Thanks for confirming my sanity... Thought everything was fine with that parallel statement and installation.

So a general update...

Did some proper testing as best I could.

General short summary in my terms is that something live is touching something neutral or vice versa.

My reasoning for saying the above is that if you open up a ceiling rose (I checked two at different ends of the house)... With an old style tester screwdriver (with the little light in) everything lights up the screwdriver! Neutral, live and switched live all light the screwdriver. Checking it with the multimeter just shows something minute like 0.8v. I assume this is because there is no real complete circuit despite every wire being "hot".

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. I thought it was related to turning on the bathroom downlights but that's not the case as it has also happened with them off, and also with other lights turned on. Bit difficult to check if the landing light is on because it has 4 switches that can control it.

So the general consensus is that it seems to trip after a few minutes, regardless of light switch positions.

There is a junction box at the two bathroom downlight setups (one each) and I also disconnected the string of 6 lights (the potentially questionable ones that flickered) from their junction box (leaving only the pull string switch and extractor fan connected). I thought this solved it as it then didn't blow but it didn't solve the problem since no other lights began to work either. Also I then touched the meter to the junction box and around the same time it tripped (could have just been a badly timed convenience).

Also checked my ceiling fan light connections as I read about that being a potential cause online. I hadn't used the fan for months until the morning of the flickering. But all connections here are solid.

Thoughts are appreciated on the above (all wires being "hot" situation)... But at this stage I'm running out of ideas and will possibly just end up waiting for an electrician on Monday (or the same guy who came today on Wednesday when he's free)

Good to note the electrician also noticed something strange in the same rose I was checking out... Dad didn't quite catch his explanation of it though but I imagine it may have been the fact that all wires seemed hot.

Thanks all

Feel free to throw any ideas out there! Will be much appreciated

 

[azibux1]

To add to the above... Regardless of switch position... Both terminals on each light switch are also hot

 

[333rocky333]

If it takes 8 minutes to trip, then thats ample time to make sure each room is off by their relevant switches and that lights in each room actually work.
Therefore ensure they are all off, reset trip and then see how long it stays on.
Bin the screwdriver it is just misleading you.

 

[deadshort]

Disconnect the extractor fan.

Regards,

DS

 

[azibux1]

If it takes 8 minutes to trip, then thats ample time to make sure each room is off by their relevant switches and that lights in each room actually work.
Therefore ensure they are all off, reset trip and then see how long it stays on.
Bin the screwdriver it is just misleading you.

Two rooms have fancy electronic switches (one touch panel one and one lightwaverf) so they do nothing anyway. The remainder we can obviously turn off we have. One was upside down in the spare room and not sure if the electrician turned it round when he looked at it today. That was the one I also looked at where both ends were supposedly hot... So not sure which way it should be.

You ask me to check which work in that 8 minutes. The answer seems to be none and checking across the rose at both neutral and live and neutral and switched live both return 0.something volts. That's the strange thing. Something somewhere isn't allowing the circuit to complete, but it also isn't shorting / tripping it instantly.

I know that the multimeter works and it was set to AC. There are two red connections at the bottom of it and the black is in the middle. I never use it often enough to remember which red to use, although I'm fairly sure it's the left one. I'll check it on a socket tomorrow to make sure it reads 230v

Disconnect the extractor fan.

Regards,

DS

Would disconnecting it from the fan end rather than junction box end be sufficient? Much easier to get to the fan itself.

Edit... Should also add that the extractor fan is already turned off at the isolator switch.. Would disconnecting it be any different?

 

[SUNRAY]

Bin the screwdriver it is just misleading you.

On the contrary, I think the screwdriver may possibly be pointing OP towards a broken neutral. Check your screwdriver on a good earth somewhere like the water pipe. If it does light up on the earth then take Rocky's advice and bin it.

Are there ANY points in the system where the screwdriver does not light?

Have you tried testing the voltage between earth and the various other wires with your multimeter?

The red hole you need to use will have a 'V' beside it, definitely do not use the Red socket which has an 'A' beside it.

 

[azibux1]

Doh! I even nearly tried it yesterday on a known working socket to check the meter but never did... I had it on the "10A" connection, not the V

Hopefully hasn't caused any damage to the meter?

Will attempt to re run tests tonight

Just to confirm I'm looking for 230v between live and neutral. And seeing which lights have it and which don't to try and pin point the issue.

You mentioned testing between live and earth also. What readings should I expect there?

 

[securespark]

With a sound earth connection, expect a similar reading between LE as you get between LN.

 

[azibux1]

With a sound earth connection, expect a similar reading between LE as you get between LN.

Great!

And is there any way I can confirm the possible broken neutral with the meter instead of the screwdriver? I assume it may be a broken neutral if I have the meter set correctly and still get 0.something volts? Which would also match up with why none of the lights work even during the few minutes before the MCB trips each time?