Odd Lighting Problem?!

[Marka]

Here's the thing...

We have lived in our house for 4 years no problems, house built circa 1983.

This weekend the lights on one of the downstairs circuits started flickering very badly and then went out. Saturday night. 21:00.

Got up Sunday morning ready to fix probably blown fuse and .....lights working fine.

17:30 Sunday night lights flicker and go out again.....this morning lights working fine.

Anybody seen anything like this before...looks like a short circuit or something but what I don't understand is why if a short blows a fuse or something it comes back on?

 

[securespark]

But you said the fuse had not blown.

If this is the case, it appears that there might be a bad connection on the live /neutral loop, which is breaking the circuit, but not blowing the fuse.

How many lights go out when this fault occurs?

 

[llykstw]

Sounds like you have a loose connection somewhere. The fuse will only blow if there is live current leaking to earth. If the live current isn't leaking, but simply doesn't reach the light fitting, or the return path through neutral is disconnected, then the light won't work (because the circuit is broken) but the fuse won't trip because there's no short.

For example, if you were to take a simple desklamp and plug it in, the light would work. If you cut the live or neutral able on the flex, then it would stop working as the circuit was incomplete, but the fuse wouldn't blow because there would not be excess current being drawn.

I'd advise that you turn off the power to the lights, remove the fuse for the relevant lighting ring at the consumer unit, remove the problematic light fitting and redo all connections at the ceiling rose. If that doesn't solve it, then do the same with the connections at the light switch(es). If that doesn't solve it, then you'll either have a broken cable or a poor connection somewhere on the mains circuit.

 

[Marka]

Thanks, I will check everything. At the moment lights in following rooms go off:

Kitchen (strip lights)
Dining room (100W single Bulb)
Hall 100W (single bulb)
Toilet 60W (single bulb)
Lounge (4x 60W Wall mounted, dimmer switch)
Outside Light (100W single Bulb.)

Cheers

 

[llykstw]

If there are a lot of lights on a given lighting circuit going off together, then locatign the problem may be tricky. Do you know if it's a radial circuit, or a chain circuit (i.e. a line of spurs ) or a ring main? Is it every single light on that circuit that's going off, or only some of them?

 

[Marka]

I don't really know.

The Garage, Utility Room and Conservatory are all OK.

I checked the Rose fixtures on the two lights that have them and they seemed OK. The wires to the bulbs were however old so I replaced them, but this did not work.

The outside light seems a bit loose so it would be my next logical place I guess.

Although the strip lights in the kitchen have always worked we only have 3 out of the 4 working at the moment ...and I know it's not the bulb. (But it has been like that for some time now.)

 

[securespark]

There is no such thing as a ring in lighting. If it were a ring then power would still be present in the other leg of the ring.

The cable leaves the CU, to light 1 to light 2 etc then stops.

There is no return leg to the CU.

Therefore, finding the break is a little easier, but you need a bit of guesswork.

Hopefully all your light fitting will either be loop-in ceiling roses or fittings where all the cables are present at the light fitting (as opposed to there being just one cable at each fitting). You need to go round looking in each position (with power off) to see if there is an obvious loose connection.

take the light nearest the ones that are off and there is a strong likelihood that the feed from that light goes on to the ones that aren't working so the problem may lie with the fitting nearest the "dead" ones.

 

[Marka]

Thanks to every one for their comments.

Traced the porblem back to the last light still working a loose wire, fixed this and all seems OK.