Breaking the myth: Incandescent bulbs don't last
January 15, 2016 at 6:35 am
(This post was last modified: January 15, 2016 at 6:38 am by Aractus.)
So it's been more than 6 years now since the sale of ordinary incandescent light bulbs have been banned (with some exceptions, such as halogens so long as they achieve at least 15 lm/W effiency). It's also illegal to import them for personal use (without a written exemption) - if they are under 150W and rated for 220V or higher. If however you want to buy a case of bulbs rated fro the American standard of 120V you're fine, and if you want to import 150W or higher you're also fine.
It is true that incandescent light bulbs are a prime example of planned obsolescence, but it is not true that they can't last for many years. Like this one of mine:
![[Image: r0MncfX.jpg]](https://i.imgur.com/r0MncfX.jpg)
Now there's nothing special about how it's plugged in. It's plugged straight into the 240V mains with no dimmer, and gets switched on and off several times a day it's the toilet light. It's been in there so long that it's developed an enviable amount of rust. It's a Mirabella brand 60W 240V light bulb, and it is at least 10 years old. This is a rarity in that it has exceeded its expected life of 1100 hours (which is about what their lights are rated for - 1 year at 3 hours per day). Now you might say, well it's lasted this long because I don't use it for 3 hours a day - well that's not really true. It's been left on overnight many many times, and the switching on and off is what causes the filament the most stress - not the continual burning of the light.
So when this one blows, how will I ensure the next one lasts for another 10 years? Simple. The life expectancy of an incandescent light is determined by the input voltage. In fact, what most people don't know, it is inversely exponentially proportional to voltage. Think of it this way, let's say you hold the light in your hand by the base with one fingertip on the bottom connector of the light, thus making a closed circuit. You are now providing about 0.2V or so to the light globe - not enough to actually make the filament glow, but it's certainly not 0V either. The light globe is rated for 1000-2000 hours, let's say it's rated 1500 hours. If you were to hold that light-bulb continually for nine days then you will have been supplying it with continual voltage for longer than the 1500 hours that it is rated for - what's the chance do you think that this alone would blow it?
A 60W globe rated for 120V is very different to a 60W globe rated for 240V. Let's consider the case of what happens if you plug the 220V globe into a 120V socket.
The 120V globe consumes 60W. We can work out the resistance of the filament as 60*(120/60)2 = 240 ohms. The 240V globe consumes 60W also, therefore its resistance can also be worked out: 60*(240/60)^2 = 960 ohms. Perhaps you have a European globe rated for 220V, in this case the filament would provide 60*(220/60)2 = 806.67 ohms resistance. So let's now consider the brightest incandescent light money can buy with a bayonet tip - 200W. We'll say the rated voltage is 220V - the European standard. The resistance of the filament is therefore 200*(220/200)2 = 242 ohms. Did you notice this is almost identical to the resistance of the 60W 120V globe? Yet it has a much heavier duty filament than the 120V globe, as explained by being rated to run at that voltage. If you were to plug this globe into a 120V socket it would consume about 60 Watts of power (59.5W to be exact). So now we know if I replace my current light with a 200W/220V globe and run it at 120 volts it will shine at the same brightness as the 60W/240V globe does.
But the interesting thing is what happens to the life expectancy of the globe. Let's say the rated life expectancy at 220V is 1500 hours. And the life expectancy at 0V is pretty much "forever". This should explain to you why the life expectancy of a globe increases exponentially as the voltage is decreased - see even at 0.2V it really should last "almost forever", and at 120V it will last thousands of times as long as it would at 220V. This only accounts for the evaporation of the filament and the stress on it of the voltage though, and not other factors such as a house fire destroying the bulb. Let's use the equation: Lifetime = 1000 hrs = (220V/220V)13*1000 Reduce to 120V and lifetime = (220V/120V)13*1000 = 2,643,252 hrs, or if you prefer, 302 years if burned continually 24 hours a day. And if you were to start with a 200W globe rated for 120V and decreased the input voltage to 65.5V you would obtain exactly the same benefit.
So they do last an awful fucking long time, just so long as you don't use them in the way intended.
It is true that incandescent light bulbs are a prime example of planned obsolescence, but it is not true that they can't last for many years. Like this one of mine:
Now there's nothing special about how it's plugged in. It's plugged straight into the 240V mains with no dimmer, and gets switched on and off several times a day it's the toilet light. It's been in there so long that it's developed an enviable amount of rust. It's a Mirabella brand 60W 240V light bulb, and it is at least 10 years old. This is a rarity in that it has exceeded its expected life of 1100 hours (which is about what their lights are rated for - 1 year at 3 hours per day). Now you might say, well it's lasted this long because I don't use it for 3 hours a day - well that's not really true. It's been left on overnight many many times, and the switching on and off is what causes the filament the most stress - not the continual burning of the light.
So when this one blows, how will I ensure the next one lasts for another 10 years? Simple. The life expectancy of an incandescent light is determined by the input voltage. In fact, what most people don't know, it is inversely exponentially proportional to voltage. Think of it this way, let's say you hold the light in your hand by the base with one fingertip on the bottom connector of the light, thus making a closed circuit. You are now providing about 0.2V or so to the light globe - not enough to actually make the filament glow, but it's certainly not 0V either. The light globe is rated for 1000-2000 hours, let's say it's rated 1500 hours. If you were to hold that light-bulb continually for nine days then you will have been supplying it with continual voltage for longer than the 1500 hours that it is rated for - what's the chance do you think that this alone would blow it?
A 60W globe rated for 120V is very different to a 60W globe rated for 240V. Let's consider the case of what happens if you plug the 220V globe into a 120V socket.
The 120V globe consumes 60W. We can work out the resistance of the filament as 60*(120/60)2 = 240 ohms. The 240V globe consumes 60W also, therefore its resistance can also be worked out: 60*(240/60)^2 = 960 ohms. Perhaps you have a European globe rated for 220V, in this case the filament would provide 60*(220/60)2 = 806.67 ohms resistance. So let's now consider the brightest incandescent light money can buy with a bayonet tip - 200W. We'll say the rated voltage is 220V - the European standard. The resistance of the filament is therefore 200*(220/200)2 = 242 ohms. Did you notice this is almost identical to the resistance of the 60W 120V globe? Yet it has a much heavier duty filament than the 120V globe, as explained by being rated to run at that voltage. If you were to plug this globe into a 120V socket it would consume about 60 Watts of power (59.5W to be exact). So now we know if I replace my current light with a 200W/220V globe and run it at 120 volts it will shine at the same brightness as the 60W/240V globe does.
But the interesting thing is what happens to the life expectancy of the globe. Let's say the rated life expectancy at 220V is 1500 hours. And the life expectancy at 0V is pretty much "forever". This should explain to you why the life expectancy of a globe increases exponentially as the voltage is decreased - see even at 0.2V it really should last "almost forever", and at 120V it will last thousands of times as long as it would at 220V. This only accounts for the evaporation of the filament and the stress on it of the voltage though, and not other factors such as a house fire destroying the bulb. Let's use the equation: Lifetime = 1000 hrs = (220V/220V)13*1000 Reduce to 120V and lifetime = (220V/120V)13*1000 = 2,643,252 hrs, or if you prefer, 302 years if burned continually 24 hours a day. And if you were to start with a 200W globe rated for 120V and decreased the input voltage to 65.5V you would obtain exactly the same benefit.
So they do last an awful fucking long time, just so long as you don't use them in the way intended.
For Religion & Health see:[/b][/size] Williams & Sternthal. (2007). Spirituality, religion and health: Evidence and research directions. Med. J. Aust., 186(10), S47-S50. -LINK
The WIN/Gallup End of Year Survey 2013 found the US was perceived to be the greatest threat to world peace by a huge margin, with 24% of respondents fearful of the US followed by: 8% for Pakistan, and 6% for China. This was followed by 5% each for: Afghanistan, Iran, Israel, North Korea. -LINK
"That's disgusting. There were clean athletes out there that have had their whole careers ruined by people like Lance Armstrong who just bended thoughts to fit their circumstances. He didn't look up cheating because he wanted to stop, he wanted to justify what he was doing and to keep that continuing on." - Nicole Cooke
The WIN/Gallup End of Year Survey 2013 found the US was perceived to be the greatest threat to world peace by a huge margin, with 24% of respondents fearful of the US followed by: 8% for Pakistan, and 6% for China. This was followed by 5% each for: Afghanistan, Iran, Israel, North Korea. -LINK
"That's disgusting. There were clean athletes out there that have had their whole careers ruined by people like Lance Armstrong who just bended thoughts to fit their circumstances. He didn't look up cheating because he wanted to stop, he wanted to justify what he was doing and to keep that continuing on." - Nicole Cooke
![[Image: 14w_t5_fluorescent_tube_3400k_549mm_excl...0-4834.jpg]](https://images.weserv.nl/?url=www.mygreenlighting.co.uk%2Fimages%2Fproducts%2Fwhite%2F14w_t5_fluorescent_tube_3400k_549mm_excl_pins-1019-1000-4834.jpg)
![[Image: 2894929.png]](https://images.weserv.nl/?url=www.endangeredpolarbear.com%2Fuploads%2F1%2F4%2F2%2F4%2F14243313%2F2894929.png)
