Light bulbs blowing

The things that spring to mind include:

The fitment is holding the lamps at an orientation where the filament is least able to take the mechanical effects of the thermal expansion on switching on.

The fitment is mechanically resonating - passing on vibration to the lamp and filament.

The fitment is causing the lamps to overheat.

If the lamps are a different design or batch to the others in use in the house, it could be poor quality lamps.

So, buying a different brand (maybe not quite so cheap?) lamps is the first thing to try, if this is the only place you are using them.

If you still have problems:

Changing the fitment for one of a different design is one possible solution.

Changing the light switch, is another - if you change to one with a "soft-start" (typically will also be a touch switch and/or dimmer). This will reduce the inrush current and thermal shock and should make your lamps last longer.

In the UK, as your email address suggests you are, it is unlikely to be the mains supply to the fitment that is causing a problem localised to one fitment.

Additional thought,

Have you checked all of the connection in/to and through the fixture?

No I haven't although I will do so when I have chance along with all the other suggestions kindly made by Palindr?me.

Thanks for the help. When I check them I will report back.

One other thought. Lamp life is severely shortened if running overvoltage. If you feel comfortable doing it, check the voltage at the lamp socket and compare to the bulb rating. Even a modest overvoltage just 6% can cut bulb life in half.

daestrom

Welcome to the mystery of short-lived light bulbs! In my apartment stairwell there are 5 light fittings, and bulbs in the top one never last very long. As the circuits are in parallel, there is no obvious reason why one circuit should be harder on the globe than any other. I swapped to CF globes, and still globes in that socket have shorter lives, about 75% shorter. (My 'solution' has been to not replace the globe in that socket, enough light relects up the stairwell that we don't need a globe on every floor anyway.)

My Mum has two 4-globe light fittings. Like yours, a globe goes u/s every couple of weeks. The electrician told her that he used to have a similar fitting with multiple 40 watt globes, and was always replacing a blown globe, and he said the only solution was to replace it with a fitting that uses a single higher power globe. My conclusion is that the low wattage incandescent globes are simply not electrically robust for regular, long term use. (I can't comment on the halogen spot light bulbs.)

-- John Savage (my news address is not valid for email)

I had this with the light fitting at the top of the stairs. Which is a sod because it is something like 40'+, straight down, underneath it. It

In the end, at someone's suggestion, I replaced one of the links, in the chain from rose to fitting, with a tension spring.

The theory was that it was vibration, caused by the water flowing in heating pipes fixed to the joist carrying the rose. Making the filaments resonate, or at least vibrating them a tad. The spring was supposed to decouple the fitting, mechanically.

Whatever, it worked. I can't recall the last time I have had to change one, now - the bedroom ones OTOH..;)

Might expalin why some fittings have more problems than other, identical, fittings in the same building..

There are multiple possible causes. But the most common are 1) high voltage, 2) heat, 3) vibration, 4) moisture, though not necessarily in that order.

You might find that a lower wattage bulb, even with the same rating for life expectancy, might last longer merely because it produces less heat. Or a different fixture might help (it might dissipate heat better, it might vibrate less, or it might not allow condensation to form and drip on the bulb).

If high voltage is the problem, obviously different bulbs, rated for higher voltage, would be a good choice. There are "rough service" bulbs rated at 130 VAC, for example.

That suggests a smaller bulb would work too.

With plain incandescent bulbs, the lower wattage units are usually more "rugged" than the higher wattage ones. That is inherent in the fact that they are smaller (sturdier) and have significantly less heat to deal with.

There are two things that shorten the life of incandescent bulbs. Chances are very good it is either high voltage, or vibration.

Even a modest overvoltage can cut bulb life in half or worse. Easy to check/detect if you have a decent meter (and decent meters don't cost that much anymore). Harder to fix though.

Vibration is sometimes harder to detect. Some places you can find a 'rough service' bulb that has extra supports for the filaments that will last longer in such cases. The extra supports built into the bulb help keep the filament from resonating and causing failure.

daestrom