Useless light bulbs.

[MikeParticipant @mike89748]

Thanks pgk. We have no short-life issues with anything on our power circuits, and the house had a reasonably recent full electrical check when a new boiler was fitted. No issues of any kind were discovered, but what I know about electricity could be writ large on the back of a postage stamp so the test may not have identified "dirty" power. I'll take your advice on the candle bulbs when I get round to fitting LEDs in the multiple-bulb setups. It's probably time they were replaced anyway – they've been there for well over 20 years.

[pgk pgkParticipant @pgkpgk17461]

My house leccy knowledge is about the level you describe. One issue we did have when i first went led was that they stayed on at low power when switched off at the wall… took local leccy guy and his mate half a day to figure out the previous persons dodgy wiring. If i understand correctly there was a neutral to ground in there giving half volts?? not enough to light up incadescents but showed up on the leds.

I'm out in the sticks and power here comes across lots of fields to a transformer on a pole 200yds away and then to me.

[Steven VineParticipant @stevenvine79904]

Now you got me going. I bought a fair few Osram Classic Eco Superstar halogen bulbs from a reputable supplier a few months ago. The bulbs are only lasting a couple of weeks. If anyone walks heavily on the upstairs floor, the bulb shakes and then destroys itself. I used one in a lead lamp a few weeks ago. I moved the lead lamp and the bulb blew immediately. I have brushed against the bulbs while they are on and they have blown. I have since read bad things about these particular bulbs (google it). If you see them, they will be cheap. Don't buy them.

I've got a million 40w Edison screw old type bulbs left over from a previous life. I have just bought some bayonet to screw adapters and am working my way through the box.

When I was on the tools, an electrician mentioned that light bulbs blow if the lamp fittings are old and loose. Makes sense.

Dirty electric! Oh my.

Steve

[Steve WithnellParticipant @stevewithnell34426]

If a filament lamp has a mean time between failure of 1000 hours and you have 10 lamps in a fitting, then a failure every 100 hours would not be unexpected, giving the impression of the fitting 'eating lamps'.

Also, the longevity of a filament lamp is strongly affected by the voltage – so reducing the voltage on a '240v' rated lamp by as little as 10 volts, makes a big difference in longevity. There's is bound to be a chart somewhere on the web showing how sensitive filament life is to applied voltage.

Going back to the 10 lamp fitting, if one lamp fails, the voltage will rise at the fitting as the load has reduced, reducing the life of the remainder, so best not to leave failed lamps in the fitting.

In the US an outfit called Brookstones used to sell a diode with the form factor of a 2032 button cell which you dropped into the bottom of a lampholder (edison screw type!!) which massively extended the life of the lamp. I tried that at home but the resulting flicker was problematic (and the dimming was too much..).

So using a dimmer and turning down the brightness a notch will massively extend the life of a filament lamp. At £1 a throw, a dimmer will soon pay for itself.

Steve

[Dave DanielsParticipant @davedaniels93256]

Light output for a filament lamp is given by Volts ^ 3.4 .

So, a 5% reduction in voltage will drop the light output by some 16%.

It will obviously rise by 16% for a 5% overvoltage.

Not sure but I think light output is directly proportional to filament temperature.

D.

Edited By Dave Daniels on 28/02/2016 19:14:38

Edited By Dave Daniels on 28/02/2016 19:16:04

[martin perman 1Participant @martinperman1]

When the power saver lamps came out ten or so years ago the gas and electricity companies were giving them away free, I replaced every single lamp in my house and only recently I have replaced the first and still have some freebies waiting to be used.

 

Martin P

Edited By martin perman on 28/02/2016 19:27:51

[davidsuffolkParticipant @davidsuffolk]

Halogen are c**p and I have gone completely over to LED which so far are fine. One point not mentioned is the LED bulbs are often warranted. I bought sets from Ledhut and had one (out of 12) fail after about 2 years. Without any quibble they sent a replacement.

LED are not cheap but at the rate the halogen were failing I have saved loads plus at only 4-5 watts they reckon their cost is saved in 6 months (and gained every six months thereafter.)

[stan pearson 1Participant @stanpearson1]

I read some ware were we are going back to the old style bulb, they have found a way of using the heat and making them more efficient .

Stan

[Gordon WParticipant @gordonw]

In my experience, not great, light bulbs fail more often than they should because of worn out switches and bad contacts in the wiring. We live in the middle of nowhere in N Scotland ,the voltage varies a lot, not as bad as it used to, I think this affects the wear rate of the switch more than the bulb (lamp)

[HopperParticipant @hopper]

Bulbs fail because they are designed to fail. One of Edison's original bulbs is still burning in the USA, for over a hundred years now.

I have found the fluorescent bulbs last for years. Got sick of changing the old type every few months.

[roy entwistleParticipant @royentwistle24699]

To be pedantic My dad always said that  Bulbs grow     Lamps glow

Edited By roy entwistle on 29/02/2016 11:02:40

[JAParticipant @ja]

Posted by Hopper on 29/02/2016 10:13:43:

Bulbs fail because they are designed to fail. One of Edison's original bulbs is still burning in the USA, for over a hundred years now.

The fluorescent light bulb was one of the earliest examples of planned obsolescence. In the early part of the last century the manufacturers decided they were lasting too long, and as a cartel, decreased their average expected life.

When the light bulb market becomes stable and the new light bulb technology becomes standardized they will do the same.

JA

[MWParticipant @mw27036]

The main reason why they fail is rate at which they are switched on and off, i'm pretty sure if one of edison's bulbs was being used like we do at home it would've gone out long ago, the key is it's never switched off if they can help it.

One of the reasons for this is the effort the electricity needs to pass through it's own (the curcuit's) innate resistance again and again. The components of any curcuit will eventually break.

Michael W

Edited By Michael Walters on 29/02/2016 12:18:25

Edited By Michael Walters on 29/02/2016 12:18:54

Edited By Michael Walters on 29/02/2016 12:19:49

[NJHParticipant @njh]

Replaced all my light bulbs with low energy types about 4 years ago when applying for RHI funding for heat pump. To date just one failures in 44 lamps!

Norman

[MWParticipant @mw27036]

Weirdest experience i had was buying a pack of 2 daylight bulbs online, i read a review before buying that the 1st one went within hours of use and the 2nd lasted well over a few years. I had the exact same thing happen to me, i think the quality of the filament varies and the amount of heat it can take changes with each one.

When Thomas Edison first made his light bulb, many others were not able to create an electric light that would sustain for more than a short period of time. So his version was actually a success not as something "designed to fail" so to speak, everyone knows they'll eventually blow but it was atleast a massive improvement on anything there was before it.

Michael W

Edited By Michael Walters on 29/02/2016 13:55:39

[Enough!Participant @enough]

Posted by Michael Walters on 29/02/2016 12:16:54:

The main reason why they fail is rate at which they are switched on and off,

One of the reasons for this is the effort the electricity needs to pass through it's own (the curcuit's) innate resistance again and again. The components of any curcuit will eventually break.

Years ago, there used to be an ad here (Canada) for a certain brand of incandescent bulb telling how they would last through a full night up North (Arctic Circle). Not real surprising since they were never switched off.

The main reason for bulbs blowing at switch on is that the filament is cold, it's resistance lower and the inrush current therefore higher. It's why bulbs typically blow at switch-on rather than any other time.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bandersnatch on 29/02/2016 17:28:55:

The main reason for bulbs blowing at switch on is that the filament is cold, it's resistance lower and the inrush current therefore higher. It's why bulbs typically blow at switch-on rather than any other time.

.

Hence the popularity of 'soft start' devices for [rather expensive] projection bulbs.

MichaelG.

.

Maybe useful reading:

**LINK**

[Neil WyattModerator @neilwyatt]

Posted by KWIL on 28/02/2016 15:59:42:

As Jason said buy Rough Service bulbs, just like the old ones, unfortunately they are all pearl (not clear)

Edited By KWIL on 28/02/2016 16:00:04

Back when I was 15 and helping out in my Dad's shop we sold more light bulbs than anything else.

I don't think I ever sold a clear (mains) bulb to anyone.

Neil

[Neil WyattModerator @neilwyatt]

Posted by Mike on 28/02/2016 16:13:31:

Why is it that light fittings with three or five conventional bulbs wired in parallel have such a high failure rate? The three in my house absolutely eat bulbs, no matter what quality is bought. All of the single-bulb lights have now been changed to LEDs, as I have discovered a cheap source that seem to be reliable. Will LEDs work more reliably in the multiple-bulb arrays? Has anyone had any long-term experience?

I have this issue with three-lamp 'candelabras' only one of them has glass bowls to concentrate the heat.

I'm 100% an LED fan, when you can get them.

Neil

P.S. I used to know an electronics designer. One of his projects was an early LED fitting to replace fluorescents. He was very proud of one that set fire to a petrol station canopy

[KWILParticipant @kwil]

Neil,

The only pearl bulbs I have ever used are outside as path illumination, to me they dont not quite look right inside any form of other lamp fitting, but then that is just personal taste..

[JasonBModerator @jasonb]

Same here KWIL I use clear quite a lot only tend to fit pearl where the bare lamp can be seen as its a bit softer on the eye otherwise fit clear.

LEDs are OK if you get the colour temp right otherwise thay can look horrid and are not nice to work under, the Warm White I find the best as they are closest to incandescent and no problem getting hold of them down here.

Just done a couple of rooms with RGB LEDs the drivers can be set to any colour of te rainbow, phase through the colours, pick up any music and change to teh beat or strobe to wake you up in the morning! Currently doing a cabinet that used teh LEDs on a roll as the light source

[Neil WyattModerator @neilwyatt]

Clear bulbs give hard shadows – obviously if a bulb is in shade this doesn't matter, but for bare-bulb applications I would say pearl every time. I was serious though, the plain bulbs sold very slowly, I always wondered why he bothered stocking them..

Cool white for kitchens and bathrooms (and operating theatres), warm white everywhere else.

Neil

[Johnboy25Participant @johnboy25]

Before the days of multi chip LED's, I would use 28 Volt incandescent lamps in applications where it was required for indicators on control panels when using 24 Volt control circuits. This was a throw back from derating the operating voltage on aircraft instruments which I've used in the past. By lowering the voltage on the filament it increases the life of the lamp by a considerable amount. There is a law I belive governing this but I can't remember what it is! 😳

[john swift 1Participant @johnswift1]

the flip side of long life indicators on control panels is this –

http://spectrum.ieee.org/geek-life/history/the-great-lightbulb-conspiracy

John

Edited By john swift 1 on 29/02/2016 20:50:54

[Johnboy25Participant @johnboy25]

John… That's interesting – I know a friend of mine had a problem with head lights failing early due to a little higher than normal charging voltage from the alternator. I suggested putting two high current diode in series with the lamps to drop some about 1.5 Volts which he did. He then google the life of a lamp with reduced voltage to find the equation for determining life expectancy of a derated lamp. All I can remember is that there was a cude root in the equation! Wish I paid more attention! 🤔

[Author]

Posts