Upstairs lighting dead - MCB seems OK

[JacobSladder]

Had a new Mains Unit installed in March. Had a couple of mystery trips since then but last night the following occured-
I left bathroom lights on (5 x low voltage ceiling downlighters on a pull switch). Wife nagged me for leaving them on. Wife turns off lights. Two minutes later switches lights on. They come on briefly and then go off.

Since then we have had no lighting upstairs. I have checked MCB, which showed no signs of having tripped. I reset anyway but without success .

I've checked a couple of ordinary bulbs that are on the circuit in a downstairs lamp and they have not blown. Total wattage value I reckon to be around 560 - 600w

Any suggestions welcome

Thanks

 

[Steve]

loose connection

 

[JacobSladder]

Are you thinking in the mains unit, or it could be anywhere in the lighting circuit?

 

[Taylortwocities]

Could be either. Always check what has been changed recently first......

 

[JacobSladder]

Developments!! Having switched circuit breaker back on, I have established that there is current going through the bathroom switch. However, it's not reaching the rest of the upstairs lighting circuit.

Two thoughts;
1)one of the bathroom transformers has gone west, breaking the circuit and if it has.....
2).......could I omit the bathroom circuit in full from the lighting circuit, thereby taking out the problem, since the MCB does appear to be functioning okay if power is getting through?

or is there something else, bar a loose connection

 

[Lectrician]

How have you checked for power?

You need to determine if there is live and neutral present.

Could easily be the MCB terminal not tightened to the busbar, or the busbar stap on the wrong time of the terminal - seen this too many times.

 

[empip]

 

[JacobSladder]

The bathroom pull switch does have power on both live and neutral side

 

[Steve]

The bathroom pull switch does have power on both live and neutral side

Your bathroom switch has a neutral terminal? Very unusual

 

[RF Lighting]

Yikes.

Do you really mean neutral, or do you mean the switched live?

Is there a switched live and neutral present at the first DL transformer?

What are you using to test the circuit?

 

[JacobSladder]

Guess I mean switched live ie two cables into pull switch (one red, one black). Tested with a tester screwdriver, it shows live on both the red and black cables irrespective of whether switch is pulled on or off. I have not tested live at transformer yet.

Later
I have been in loft and totally removed bathroom lights from circuit and replaced with a simple bulkhead light. The junction box from which this runs shows as live on every screw connector indicating, I guess, that with the MCB in place the lighting circuit is live...yet still not a bulb on the circuit is working. I've tested two of the bulbs in a lamp and they are okay.

If MCB is faulty, how would the circuit show as live?

If anybody lives in the Benfleet Essex area and wants a bit of homework, be my guest!

Keep the suggestions coming, and thanks to all those who've replied so far.

 

[bernardgreen]

First neon screwdrivers are NOT a sensible way to test for live. They can give very misleading amd in-accurate results.

But if it is working and every wire is showing live then it is most lilely that the NEUTRAL is missing due possibly to a broken wire or most likely a loose connection.