Intermittent light fault - diagnosis help please!

Hi,

Advice needed please. The light in our hall has an intermittent fault and I can't work out what to do/test.

The light can be operated from a single switch by the kitchen or a multiple switch by the front door that also controls the upstairs and outside security lights. It is earthed at the ceiling rose and the light switch.

It had worked fine for four years or so then a few months ago we'd notice that the bulb would go out, then would (maybe) come back on some minutes later.

I have opened up the switch boxes and checked the wiring, I have replaced the bulb and I have just replaced the ceiling rose. With the new ceiling rose the bulb is still temperamental but can sometimes be lit by wiggling, although I was wondering if the wiggling was actually working by me providing an earth.

All the other lights work ok. House dates from mid 80s. There's no RCD on the consumer unit.

Have I been unlucky with fittings or is this some complicated earth loop thing? What can I check myself without having a thorough electrical test (which is the next step)?

Thanks in advance,

Mat

You are not going to cure this fault simply by changing parts.It will probably only need simple not complicated electrical tests to identify the problem, but you do not appear to be equipped to carry them out. It could indeed be something to do with loop wiring but probably not the earth. I would suggest you call in an electrician, it shouldn't cost that much, an hour or two's labour I would have thought.

When you say you checked the wiring, do you mean you checked the terminals were tight, give the wires a good wiggle? What you have certainly sounds like a loose connection somewhere, and if the connections in the switches and the rose are sound it suggests a junction box on the route which has come loose over time - probably not fully tight originally and loosened, just a fraction, by the vibration of people walking over it. My first suspicion was a loose wire in the rose, but then you said you'd changed it ...

pj

When you changed the rise did you also change the bayonet fitting and the drop sure ? Assuming it's a dangler ?

And wiggling it has nothing to do with earth

some of those words make sense?

Why would you change the rose but not the fitting, a pendant is about £3, you barely save any money by changing the rose but not the lamp holder

Thanks both. I took the new (I think) bulb out and it turned out one of the pins on the side was loose and there was rattling inside. I put a different bulb in and it worked. This may yet be a case of multiple duff bulbs, although maybe it only broke when I was wiggling to get it working in the first place!

To respond on the inspection point, when I opened things up I checked the connections were tight and did indeed have a wiggle. I noticed an earth wire was not quite screwed in, although *probably* was in contact with the other earths. I screwed everything back in and closed it up.

I will see if the new bulb has indeed sorted it and if not will get an electrician in.

Just to clear up one point, Ramekin, the earthing has nothing to do with the light working - the earth connection is there in case of a fault to give the electricity a quick path to the ground, rather than through you. It's the live and neutral that are making the lamps glow. The fact that wiggling the wires sometimes makes the lamps work points to a loose connection.

pj

PS if wiggling fails, try jiggling instead.

Just seen the new posts.

Re rose: terminology error on my part. The thing I replaced had a box at the top, a cable hanging down, and a bayonet fitting at the end. I removed the old ugly light and put a shade on the thing I just fitted.

Re wiggling: I was wondering if there was a tiny chance the fitting was finding a path to earth through me and it wasn't the wiggling. Clutching at straws I admit!

Iggifer said:

some of those words make sense?

Click to expand...

They all make sense individually.

It's the way that they are arranged in sentences that's the problem

Ramekin said:

Re wiggling: I was wondering if there was a tiny chance the fitting was finding a path to earth through me and it wasn't the wiggling. Clutching at straws I admit!

Click to expand...

I can assure you that if current sufficient to make it light up was passing through you you would not have been able to post here, and your nearest and dearest would be the ones doing the clutching.

Of handkerchiefs....