OT:Extending light bulb lifetimes

We have that many multi-bulb light fittings in the house that a monthly ritual now is buying a bagful of replacements, particularly in winter.

Has anyone had any success dropping the voltage say 5-10% to extend the life?

I've tried using higher wattage lamps with a diode in series, but the flicker is intolerable. The only other "lossless" ideas I have is either a series 330uF capacitor or equivalent inductor, but they would need to be rated at than 2 Amps to be sure.

I can do the maths, but wondered if anyone had tried this in practice - whats the chance of a catastrophic failure causing a fire at some point in the future?

TIA

Steve

Reply to
Steve
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Someone once said to me about leaving brand new bulbs on for 20 minutes when put in rather than the quick test that the bulb works.

I was wondering if there was something in it, maybe the length of time on will allow the bulb to be tempered. (Air surrounding the filament will have had time to warm up, keeping the filament from cooling down too quickly and becoming fragile.)

You could of course try the energy efficient bulbs. They are supposed to last much longer. Also, don't put close fitting shades (like goldfish bowls) around the bulb, as that is supposed to shorten the life.

As for your suggestion, I don't know.

Best regards, Dave Colliver.

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Reply to
Dave

We had exactly the same problem. It seems that when all 3 bulbs are running it only takes a short while for one to go, replace that and another goes etc. Once you get down to just one bulb it lasts for ages. We changed onto those energy bulbs about 5 years ago and noticed that this problem stopped. We are just now starting to have to replace these energy bulbs as they wear out

-- Regards,

John Stevenson Nottingham, England.

Reply to
John Stevenson

An appropriate NTC in series would give a slow start. However these do run hot so I'm not actually recommending the practice.

I suggest you try to move away from filament bulbs.

Jon

Reply to
Jon Schneider

Another solution is to use ordinary dimmer switches. Quite cheap. Most are only rated about 250W but you can get them at 400W.

Alan

Reply to
Alan Marshall

burning, apparantly because it is run on a very low voltage, and is never switched off and on, thus avoiding the initial surge. It was stated however, that the efficiency of light bulbs is very much reduced if run at lower than intended voltages,even marginally, although drawing a similar current. Perhaps this would cause the bulbs to last longer, but the running costs to be more ?.

I also remeber a Ferguson T/V that used a series capacitor to drop some voltage to the valve heater chain, dropping the volts whilst consuming no power. This was used instead of a dropper resistor because the T/V was very small and the capacitor did not dissipate any heat. It was a paper capacitor rated at 250V AC (I think) and I never saw or heard of one of these sets catching fire.

How about trying a starter cap from a single phase motor, and measuring the effect ?

Best Regards

Tom.

Nunce excretia in exrtactum est. fire

Reply to
Tom Jacobs

Strange that - as each bulb fails, the voltage should rise (very slightly as the voltage dropped across the length of the supply lead reduces) , reducing the life of the remaining ones.

I've used these were I can - the last one was a hall light left on for the little lad. It did about five years on every night all night!

Thanks

Steve

Reply to
Steve

These are decorative fittings - golf ball types on a small baynet cap etc, so filament is really the only option just now.

Reply to
Steve

The life of the filament is very sensitive to voltage, as a purely rough example, a 5% increase in voltage can half the lifetime of the bulb, with a significant benefit for reducing the voltage slightly.

I'm not too sure about filament shock.

As a kid, one trick was to connect 12v car stop lamps across the mains and switch on. The filament survived, but the glass bulb was destroyed everytime. This might have been because the mains fuse was quicker than the filament...

Reply to
Steve

Hehehehe

I remember when I was about 8, I had a torch bulb that I connected across the mains. I had gone the dangerous route. I had put wires in the plug socket held in by a plug, then the other end of the wires onto the bulb contacts, then with my nose, switched on the plug socket.

VERY BIG BANG!!!

My mother came running to see what I had just done. (I didn't even get to see the bang, my face was turned away trying to switch the plug on)

They certainly don't last long with 240 volts shoved through 'em.

Dave.

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Reply to
Dave

I had the same problem. The issue in my case was heat build-up in the enclosed flush-mounting ceiling fitting. I drilling some extra ventilation holes through the base (and ceiling), and this significantly extended bulb life. I also found a cheap source of bulbs - Screwfix do the small bulbs in packs of 10 for £2.80.

Mike

Reply to
Mike Crossfield

Dropping line voltage by 5% should increase incandescent life expectancy by about 80%. A 10% voltage decrease would more than triple life expectancy. However bulb efficiency would drop by 18% and 40%. Voltage is the major factor in bulb life expectancy. Power cycling is irrelevant except when bulb is already in its last hours of operation.

Another way to accomplish same life expectancy increase is to obtain 240 volt bulbs for 230 volt service. A bulb that gets too hot also overheats filament; damage just like too much voltage.

NTC thermistor was a trick once promoted in the 1950s. Idea was that bulb getting too hot too fast would burn out. Scam was eventually exposed. Urban myths are promoted quickly. It takes time for honest facts become accepted once the consumer 'believes' a scam. In reality, those few volts lost through waste heat in the thermistor increased bulb life expectancy.

If bulbs are not meeting manufacturers life expectancy, then check line voltage from utility. They are suppose to adjust voltage with changes of customer demand. Sometimes they do not do their job.

Another envir> The life of the filament is very sensitive to voltage, as a purely

Reply to
w_tom

The life of a tungsten filament lamp is proportional to the ratio of rated to operating voltage to the power of 12 or 13, depending on construction and technology (coiled coil, halogen). Thus, reducing the operating voltage to

90% of rated voltage increases life by a factor of 4 (and reduces light output to around 70%).

A snag is that the mains voltage varies by this sort of amount anyway.

Reply to
Tim Christian

Thanks Tom. Useful stuff.

Steve

Reply to
Steve

Convert the house lighting to DC, your bulbs will last much longer, also when you get to the last of the 3 bulbs, take it out and save it. Run the next two sets, to get the long lasting bulb, then fit and forget these bulbs

8-))

Joules

Reply to
Joules Beech

I remember a construction project in one of the electronic hobby magazines in the eighties (hobby electronics or electronics today international I think) for a light bulb life extender. I don't remember the details of how it did it but the basic principal was that bulbs almost always blow when being switched on, due to the sudden power surge going through them. As the power is AC the actual voltage is fluctuating all the time, and at switch on the bulb will get anywhere between 0 to 240v depending where the AC cycle happens to be at that time. The device ensured that the bulb was always switched on at the lowest possible voltage, so it didn't get a sudden 240v kick to start it up.

Perhaps a simple alternative to the circuit would be a dimmer switch and always "fade up" the bulb instead of dumping full power straight through it. You would also stop turning up the dimmer switch when there was enough light, so probably not use the bulbs at full power either.

Regards

Kevin

Reply to
Kevin Steele

You will not find an industry publication that says "sudden power surge going through" light bulb causes the damage. Principles are long and well defined. If 'power on' damages bulbs, then AC power turning on and off 100 times per second would also damage bulbs. If this was true, then all light fixtures would convert AC to DC to extend bulb life.

Even the DC power solution is classic urban myth - presented only with speculative reasoning.

Previously posted:

That theory has long since been debunked. Unfortunately, many still speculate that 'power on' damages a bulb only because they have seen bulbs burn out during power on. They fail to notice black deposits inside the glass meaning filament has been so damaged that even a so gentle shock called 'power on' can terminate the filament.

Even the gentle shock called 'power on' can severe a weakened spot on filament when bulb has seen too many hours of operation.

If bulb life expectancy was shortened by 'power on', then those orange traffic light bulbs would burn out faster AND would burn out before or same as green bulbs. Orange bulbs flash all night long. In reality, orange light bulbs last many times longer than green or red - because hours of operation determines bulb life expectancy.

Dimmer switch > I remember a construction project in one of the electronic hobby

Reply to
w_tom

In practice, a 330uF capacitor rated for AC mains would be a substantial beast, and expensive.

An inductor for 5% voltage reduction on a 60W bulb turns out to be of the order of a henry, and need either VERY thick wire or ot would have too high a resistance to be useful (you may as well use a resistor instead!)

Which leaves an auto-transformer.

In the days when AC mains was either 240V, or 230V, or 220V, depending on where you lived, mains transformers were often made with multiple tappings, and you connected the appropriate one to your mains supply. Well, a suitably rated one of these would make a good autotransformer, with mains connected to 240V, and multiple lamps on the 230V (or 220V) tap.

Alternatively, a 12V 5A (i.e. 60W) mains transformer with the primary connected across mains, and the secondary wired between live and the "live" to the bulbs, would let you run up to 5A (over 1kw) of lighting off either 228 or 252V, depending on which way round you wire the secondary!

Caveat: If you don't see exactly what I mean and why it works, please don't try it.

(And I recommend using a transformer at least 50% larger, say 100W, in the role above. Why 5A? because that's the normal circuit breaker for a lighting circuit. Scale down as appropriate)

- Brian

Reply to
Brian Drummond

w_tom wrote

"You will not find an industry publication that says "sudden power surge going through" light bulb causes the damage. Principles are long and well defined. If 'power on' damages bulbs, then AC power turning on and off 100 times per second would also damage bulbs. If this was true, then all light fixtures would convert AC to DC to extend bulb life."

I always thought that the reaon for power surge problems was that the power was applied to a cold filament, and that the cold resistance was lower, thus causing momentary high current. This does not happen during normal use on A.C. as the filament is warmed up with the first cycle or so.

Hey ho, another urban myth destroyed.

Best regards

Tom.

Nunce excretia in extractum est.

Reply to
Tom Jacobs

Two things come to mind - The first is dimmer switches and the second is the low power bulbs - not together though.

Reply to
Neil Ellwood

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