Fluorescent lighting query...

[Marcus Fox]

Council fitted new bathroom lighting when we had our electrical wiring checked by them sometime early last year, or late 2004. Now it's not working. By not working, I mean that the light is very very dim when switched on (useless in darkness as you have to look at the light to see that it's on), and flickers to normal brightness at random occasions. I have managed to identify the bulb that the lamp takes, it can be found here

have removed it from the fitting and there are dark deposits around the ends where the bulb connects to the fitting and the curved parts at the top of the picture. What is the likely diagnosis? New bulb, which I can quite easily fit myself for the cost of a bulb, or something else which will probably have to have in a council repairman - zero cost, but quite a long time with no lighting in the bathroom.

Marcus

[Marcus Fox]

Sorry, should be clearer. It is very dim when switched on but it doesn't flicker from dim to permanently on but flickers very rapidly like some sort of crazy strobe.

Marcus

[Andrew Gabriel]

Bulb worn out.

Make sure you get the right replacement lamp. There are a number of different power ratings, and a choice of 2-pin or 4-pin lamps, and none are interchangable.

If it bothers you, you might want to check which white colour you get. They are commonly available in either Warm White (2700K, sometimes marked 827, which matches filament lighting) and White (3500K or 4000K, sometimes marked 835 or 840, which will look better if the room is brightly lit and not mixed with filament lighting).

[Marcus Fox]

Thanks, that confirms the original diagnosis. There is information on the lamp which enabled me to google for the correct one, I will simply take the old bulb to the electrical shop tomorrow and have them replace it with one of the exact same model.

Marcus

[Dave Liquorice]

Assuming by "fitting" in the above you mean the plastic bit that is part= of the bulb rather than the bit remaining attached to the ceiling and that the dark deposits are inside the tube then as Mr Gabriel has said it's a worn out tube.

Just over 12 months doesn't seem a very good life. These sort of lamps don't really take to short on periods combined with being switched on/of= f frequently, such as you are likely to encounter in a bathroom/toilet. It= might be better to leave in on during the evening. The power it consumes= is going to be fairly minimal and if it extends the lamp life by 3 or 4 =

times then you could well save money.

EG over 4 years: Replace lamp every 12 months @ =A35 a throw =3D =A320.

Leave lamp on for 6hrs every night 16W x 6 x 365 =3D 35 units =3D~ =A32.=

50 =A32.50 * 4 =3D =A310.00 plus one lamp @ =A35.00 =3D =A315.00.

These lamps are normally rated at 8,000hrs or 3.65 years at 6hrs/day so =

the 3 to 4 times life extention is not unreasonable. Not that no account= of power used by the switched and replaced often lamp is taken into account and 6hrs/day 365/days a year is probably quite excessive, so power used will most likley be less, and lamp life even longer.

4hrs/day/365 drops the total power cost for 4 years by =A33.50 and life,= in theory, goes up to around 5 1/2 years...

[T i m]

We have CFL on 'dusk to dawn' lampholders on the front and rear lobbys and I can't remember the last time I changed either of them (on all night and have been there 'years') ;-)

We have just the CFLin the toilet (no dusk / dawn so turned on / off frequently) and I can't remember changing that either (good lifespan or my memory is failing) ;-(

All the best ..

T i m

[meow2222]

Or you may find that instead of lasting 12 months the next one lasts far less, and merely winds up costing you several times the amount for your irresponsibility.

Lamp hour rating is average, and with cfls especially there will be a percentage that go down prematurely, and a percentage that do well. I had one over 20 years old die last year.

NT

[Andrew Gabriel]

No it's not. I have a couple of 21W 2-D lamps in a bathroom on instant-start electronic control gear, and they are 2-3 years old, with frequent switching and no sign of failing.

[Marcus Fox]

The light is on practically 24/7

Marcus

[Dave Liquorice]

So thats about 8,000 hrs, the nominal lamp life. Though for a bathroom I don't see why it has to be on for so long. Rooms that are dull during the day and frequently occupied OK but a bathroom?

[info]

FYI...

Fluorescent lamps are not like incandescents when it comes to life. Its really the starting that wears them out. The manufactureres assume a 3 hours burrn per start and then add it up. Also rateing bulbs is destructive so they burn a batch and when half of them are dead they check the clock and pass the whole production run.

RickR

[meow2222]

Left on 24/7 the tubes can last upto twice as long. So its still better to swtich them off when not in use.

NT