[HN Gopher] Teardown of a $1.25 LED Lightbulb
___________________________________________________________________
Teardown of a $1.25 LED Lightbulb
Author : teucris
Score : 215 points
Date : 2020-02-19 15:09 UTC (7 hours ago)
(HTM) web link (electronupdate.blogspot.com)
(TXT) w3m dump (electronupdate.blogspot.com)
| m0zg wrote:
| Has anyone here done any rigorous testing wrt flicker in
| particular? Of the reasonably priced brands (which excludes Hue),
| what's the lowest-flickering warm white bulb?
| lgleason wrote:
| My entire house has been converted over to LED.
|
| The cheaper the design the higher the failure rate. The heat
| seems to kill these things over time. For example I just ordered
| another warranty replacement from one brand called Hyperikon that
| uses similar types of designs for floods in my Kitchen. These
| have a much higher failure rate. Others seem to last forever.
| Between using electrolytic Capacitors and other tings that are
| prone to heat and small enclosed areas it is no wonder that the
| newer, cheaper bulbs fail quicker.
|
| Since one big reason for going with LED is to be more energy
| efficient and greener, it would be interesting to compare the
| carbon footprint of these cheap LED bulbs that fail quickly with
| an incandescent and CFL over the entire lifespan. If the bulb
| lasts longer the numbers are pretty easy, but given short
| lifespan of some and their use or rare earth elements it would be
| interesting to see the full analysis of the environmental impact
| of each one.
| dreamcompiler wrote:
| It's ironic that LEDs themselves last for 30,000 hours but
| bulbs created with LEDs can wear out much quicker than
| incandescents because of crappy power supply design. I can't
| help but think manufacturers must have initially worried that
| LEDs would kill their continuing revenue streams. When they
| finally figured out they could design the power supplies to
| fail quickly, they must have been dancing in the streets.
| jml7c5 wrote:
| I would consider market forces a more reasonable explanation:
| most people are going to pick the cheapest option. The
| success of cheap, flickering bulbs attests to that, I think.
|
| It doesn't help that the old Edison screw is terrible for
| cooling.
| homero wrote:
| They make good ones but i pay $15 for a Philips with a metal
| heatsink and proper power supply
| derekp7 wrote:
| The problem is that the heat from the power supply needs some
| place to go. So installing the bulb upside down traps heat,
| and putting them in an enclosure also traps heat. Probably
| 90% of installations is one of these two.
|
| I've put in some "filament" style LEDs, these look like they
| will last longer as there doesn't appear to be a power supply
| taking up half the bulb (although there are electronics down
| in the screw part).
| bradstewart wrote:
| Yep, heat definitely apepars to be the biggest factor in these
| bulbs dying. I have Hyperikon BR30 bulbs in various locations.
| About half of the bulbs installed in insulation-contact
| recessed cans have died, but those in exposed fixtures are
| fine.
|
| Philips bulbs seem to do much better in the ceiling. If only
| they'd make 3000k bulbs...
| WalterBright wrote:
| You can only install LED bulbs in fixtures that are open to the
| air. There are some newer bulbs that claim to be heat
| resistant, we'll see.
| ants_a wrote:
| Even open to the air might not be enough. I just had a couple
| of self described "revolutionary thermal design" [1] bulbs
| fail after less than a year in a one end open glass fixture.
|
| [1] https://energenie.com/item.aspx?id=8293
| BlueTemplar wrote:
| Not to mention that the "wasted" energy of incandescent light
| bulbs, might actually not be, at least not entirely - since
| they pretty much work as electric heaters...
| tasty_freeze wrote:
| Resistive heaters are very low efficiency when compared to
| heat pumps. How much more efficient depends on the climate
| you are in, of course. So, in net, they require more cooling
| in the summer, and the heat they provide in the winter is
| more expensive than the heat pump that you are likely to be
| using (in a home anyway).
| [deleted]
| pwg wrote:
| During cold winter months, when one is otherwise attempting
| to add heat to the indoors, the 'waste' heat from
| incandescent bulbs is not really 'wasted', since it
| contributes slightly to maintaining the interior room
| temperature.
| teruakohatu wrote:
| If they are resessed down lights you mostly end up heating
| roof or ceiling space. And in summer not only do you
| consumer power for heat you don't need, you end up
| consuming power to remove said heat with AC. Also in winter
| there are much more efficient ways to heat than
| electricity, such such as heatpumps.
| wtdo wrote:
| I'd imagine on the whole it's wasted. Half the year they
| aren't just generating wasted heat, they're increasing
| cooling costs. The half of year that the heat is wanted, it's
| usually above you, and I imagine that heat is being generated
| less efficiently than a purpose-built device.
| anchpop wrote:
| > I imagine that heat is being generated less efficiently
| than a purpose-built device.
|
| All the heat that comes out of a lightbulb is being
| generated at 100% efficiency :)
|
| (Although it's likely more expensive to heat your home
| electrically instead of via natural gas)
| mmcnl wrote:
| Heat pumps have higher than 100% efficiency because they
| extract heat out of air / water. 100% is a very low
| efficiency for electric heating. Anything lower than 400%
| is considered below average.
| krallja wrote:
| > that heat is being generated less efficiently than a
| purpose-built device.
|
| "efficiency" is meaningless when heat is desired. if you
| pump 100W into a device, and it "wastes" all that power,
| you have successfully generated 100W of heat. only heat
| pumps can be more efficient.
| hristov wrote:
| "only heat pumps can be more efficient"
|
| Exactly. And if you have a whole house/apartment electric
| heating system it is very likely that it is in fact heat
| pump based. So you are better off using that for heat
| than the lights.
|
| If your whole house/apartment heating system is gas or
| oil based, that will probably be even cheaper than the
| heat pump electric version.
| ubercow13 wrote:
| >if you have a whole house/apartment electric heating
| system it is very likely that it is in fact heat pump
| based
|
| Hmm, where? I have never knowingly been in a house with a
| heat pump in the UK, and lots of cheaper flats have
| electric radiators and immersion heaters.
| tomatocracy wrote:
| This is true but - especially if your house is not well
| insulated - getting heat in the right place matters too -
| most people don't need to heat their roofs or ceiling
| spaces. There's also a more minor point on time of day
| you want heat or not.
| tonyedgecombe wrote:
| Although heating with gas will produce different amounts
| of CO2 than heating with electricity.
| quietbritishjim wrote:
| Not quite - some energy was lost converting from its
| source form to electricity. If you heat your house by
| directly burning natural gas (the most common way in cool
| countries like the UK) then it can still have an
| efficiency advantage over converting electricity to heat.
| detritus wrote:
| I had pretty much this exact thought recently after a couple of
| LED bulbs failed in fairly close succession in my house,
| despite a purported 20/50K hour lifespan (I can't recall which
| exactly, but neither reached).
|
| They're own-brand ones, sold by a major supermarket chain here
| in the UK (Sainsburys), so I'd expect them to be 'ok' at least.
| Certainly not 'cheap'.
|
| Compared to ye olde incandescents, the complexity and material
| make up is significantly less recyclable and looks to my eye to
| require a lot more invested energy to manufacture.
|
| -
|
| I've wondered this about so-called 'smart meters' too - how
| much energy does it take to make one, and how long to 'pay off'
| that investment?
| yjftsjthsd-h wrote:
| Were smart meters about saving energy? I sorta assumed they
| were just there to make things easier on the power company.
| Although I suppose if it means that a person doesn't have to
| drive a car to every meter every month, that's probably a
| win.
| joosters wrote:
| Smart meters in themselves don't do anything to save
| energy. However, they make your energy consumption level
| more visible, which in turn might encourage you to use less
| electricity.
| bcrosby95 wrote:
| I think they can help with saving energy indirectly: by
| letting power companies give customers more detailed
| information about their usage. But I don't know how often
| people take advantage of this.
|
| I've shaved off around .15 kwh of energy that was used 24/7
| ($25/month in California) based upon usage information from
| our energy company.
| joezydeco wrote:
| My 'smart meter' is Zigbee enabled, and I own an adapter
| that spits out data from the meter in XML format. I can
| see power consumption with ~400 Watt resolution every 10
| seconds without messing around in my breaker box
| attaching things.
|
| Downside is that we're a decade into net-connected
| thermostat and HVAC systems and none of them support any
| of this.
| lopmotr wrote:
| A crude way to estimate embodied energy is just from the
| cost. It had to take less than $1.25 worth of energy to
| produce and distribute. That might have been something cheap
| and polluting like heat from coal, but it's still not much.
| You could look up the cost of that in India or China or
| wherever it's cheapest to get the worst case amount of energy
| or CO2 emissions.
|
| Alternatively, plastic takes about 100 kJ/g to produce. So if
| the bulb has 1 g of plastic, that's about 0.03 kWh of energy.
| Nothing compared to the savings in electricity using it.
| larrik wrote:
| > It had to take less than $1.25 worth of energy to produce
| and distribute.
|
| Not always, they could be subsidized to get people off of
| incandescents.
| makomk wrote:
| Where this gets interesting is when governments decide that
| if LED energy efficiency is good, more LED energy
| efficiency is better. There's a push for minimum energy
| efficiency standards to be really close to the cross-over
| point where consumers just barely save money compared to
| less efficient bulbs if they meet the nominal lifetime
| specs, on the pretense that it's helping out consumers who
| are too stupid to realise that the higher upfront cost
| saves them money - at least in the EU and the US pre-Trump.
| Given the combination of more complex designs and more
| incentive for cost-cutting, I can't see those bulbs meeting
| the lifetime specs, and I do wonder if it'd actually save
| energy.
| ineedasername wrote:
| Yes, the "lifetime" of the bulb tends to be quoted in terms of
| the expected life of the specific light emitter, i.e., the LED
| itself. In reality, something else almost always fails first,
| and much much faster.
| zippergz wrote:
| I have some spots in my house where it's a major hassle to
| change the bulbs, so the long lifetime of LEDs was an important
| selling point there (in fact, much more important than the
| energy savings). Thankfully I've had good luck with those (all
| Cree bulbs), but I'd be pretty annoyed if I bought LEDs for
| those fixtures and ended up having to replace them after a year
| or two.
| julianlam wrote:
| A year or two would be fantastic! I replaced all the halogen
| bulbs in my house with Uberhaus GU10 and PAR20 LEDs. They
| last on average about 6 months.
|
| They were a dollar Canadian after government incentive. You
| get what you pay for.
| zippergz wrote:
| I'm on year 5 or 6 right now with the Cree bulbs I bought.
| 9HZZRfNlpR wrote:
| That sounds awfully bad, even my cheapest of the cheap
| bulbs last minimum 2yrs. Are you aware how's the quality of
| power coming into your house?
| Marsymars wrote:
| If you're in Canada, I've had good luck with Luminus Elite
| (different from the Luminus non-elite available at non-
| Costco locations) PAR20 and GU10 bulbs from Costco. Or I
| use Philips warmglow from Home Depot or comparable Ikea
| bulbs (which have brighter GU10 than the Luminus Elite
| line) in locations where I want non-ugly dimming.
| pkaye wrote:
| I replaced a dozen halogens with Torchstar LEDs from
| Amazon. They have lasted for 3+ years so far. The old
| halogens used to fail, once every 6 months.
| johnchristopher wrote:
| I am reading this post on my laptop, in bed. In my grand
| parent's house.
|
| There's a bedside lamp next to the bed and the bulb is at least
| 30 years old. Two generation of children have used that bedside
| lamp to read stuff at night or walk to the bathroom.
|
| Meanwhile my LED - whatever the brand - are failing between 6
| months and two years.
|
| edit: https://imgur.com/c6B71B4
| zippergz wrote:
| Somwething seems wrong if your non-cheap LEDs are dying that
| quickly. I have an entire house of LEDs, many going on 5-6
| years old, and I only ever recall replacing two (and they
| were a pair, used outdoors -- only one failed, but I replaced
| both so they would match).
| ujjjujjj wrote:
| Perfect! A great picture of the lightbulb. Its easily
| identifiable not :)
|
| Nonetheless in the last 20 years all my normal light bulbs
| had to be replaced on a regular schedule which was often
| enough that i got slightly annnoyed by it.
|
| My expensive philips hue, no issues so far.
| spookthesunset wrote:
| Some of these cheap LED bulbs have horrible flicker. For a fun
| time, record a slow motion video of a cheap bulb on your phone
| and play it back. Like half the damn video is black (pretty sure
| it is because they literally chop out half the AC sine wave with
| a diode). LED Christmas lights are also really bad.
|
| Then compare it to something like a Phillips hue bulb. The
| difference between the two is pretty big.
|
| On a side note I sometimes wonder if other animals have a quicker
| "refresh rate" on their eyes and see nothing but very visible
| flicker on these bad LED bulbs. I also wonder if some animals
| could see the raster scan in action on old CRTs...
| Tepix wrote:
| Are there any statistics how many people perceive this flicker?
| I see them complain in online forums but I'm not sure if it's
| just a very loud small minority.
|
| What does it take to make them not flicker? I.e. how much of a
| cost increase is required?
| uxp wrote:
| Based upon this article were the retail costs of a cheap
| flickering LED bulb is approaching the single dollar mark,
| the cost increase to use a proper AC/DC converter could be
| orders of magnitude more expensive (at a rough minimum).
|
| Honestly it's starting to feel like a most cost effective
| long term solution is to build homes with a master AD/DC
| converter (or several depending on sq/ft) and simply wire 12v
| outlets and light fixtures. The energy savings of swapping
| all incandescents or compact florescence bulbs with cheap
| LEDs with cheaper power converters is starting to scare me
| knowing just how shoddy and fire prone some of these power
| converters can be.
| BlueTemplar wrote:
| I expect USB-C outlets to become common in new homes...
| 0xff00ffee wrote:
| Funny you mention animals. I often wonder if home environments
| have become screaming dens of high-frequency noise for dogs and
| cats. I know that flourescents tend to osciallate around 40kHz,
| and I definitely have an LED bulb that whines for some reason.
| Not to mention cheap laptop power supplies that also whine over
| time.
|
| Are all these cheap SMPS driving our pets insane? (or just
| annoying them? or neither?)
|
| I wonder if I could rent some super-high-quality mic from a
| local sound reinforcement studio and look at a 20-60kHz FFT ...
| or do fancy mics not really go beyond human hearing?
| dspig wrote:
| High quality recording mics and even mics designed for
| acoustic measurements usually (and deliberately) only go up
| to 20-40 kHz though roll off more gently than human hearing.
| Usually there is a mechanical resonance that's tuned to get a
| flat frequency response up to a point rather than a wider but
| rolling off response. A few specialist mics get up to 100
| kHz, or some sort of laser vibration measurement...
| macNchz wrote:
| Yes I find these cheap LED bulbs nearly intolerable-the flicker
| is especially noticeable because they transition so quickly
| from fully illuminated to fully dark. I've always perceived a
| slight flicker from fluorescent lights but because the
| phosphors smooth it into more of a fade in and out it's much
| less distracting. I definitely think people perceive these
| things differently...I recently stayed in a hotel room lit
| entirely by these cheap LED bulbs and it was the first thing I
| noticed from walking in. It really bothered me that every light
| fixture strobed as I moved my eyes, but my girlfriend barely
| noticed it and only after I pointed it out.
|
| The OLED displays in current smartphones also exhibit a visible
| strobe effect at lower brightness settings. I figured I'd get
| used to it but ended up returning my iPhone 11 pro after a week
| because it was driving me nuts. I've met a few people who
| perceive it as well but most seemed to have no idea what I was
| talking about.
| gibolt wrote:
| Pigeons have a "refresh rate" of around 100 frames per second.
| It is believed that a bunch of smaller animals and even insects
| have similar or faster visual processing time, though I'm not
| aware of specific numbers.
| ksec wrote:
| I have been thinking about this for years! I think we need a
| new marketing term along with a independent organisation to
| push for a new LED Standards.
|
| Let say it is called CLED,
|
| And it requires the following features / spec before it could
| be called CLED. From PWM, Colour Correctness, Energy
| Efficiency, heat etc. The different between a low price light
| bulb and higher priced is relatively minimal , the difference
| in LEDs is massive. To be point they should not even be allowed
| into the market in the first place.
| tomatocracy wrote:
| Brand (and in some cases sub brand) is a reasonably good
| proxy for this already though. Philips bulbs for example tend
| to be very good.
| LinuxBender wrote:
| I can tell when I am around these bulbs. It is the same with
| fluorescent lights for me. They make me (more) grumpy. The more
| expensive LED lights have full wave bridge rectifiers and
| capacitors with no flicker. I've considered just building my
| own for my next home.
| tomatocracy wrote:
| Some LED lights/bulbs also incorporate phosphorescent
| materials and use UV LEDs to stimulate the phosphor which
| helps too. This is also one of the ways better colour
| reproduction can be achieved. This comes at a slight
| efficiency cost though, I think.
| extrapickles wrote:
| Most LED lights use the UV+phosphor technique as its
| cheaper than doing RGB (If the LED is yellowish when
| switched off, its using this technique).
|
| The best flicker-free lights are ones that have low ripple
| constant current power supplies (somewhat expensive). LED
| lamps intended for use around rotating machinery used to
| all be this way until someone figured out that if the PWM
| frequency was wildly unstable it would prevent the problems
| with strobe lights around spinning things at a fraction of
| the cost.
| all_usernames wrote:
| Dogs apparently have a visual sample rate of around 75Hz,
| meaning they wouldn't see much in an old analog TV, but newer
| HDTVs might look realistic to them.
|
| https://thebark.com/content/heres-what-dogs-see-when-they-wa...
| brutt wrote:
| Yep. See https://www.youtube.com/watch?v=Q-p747h4HKw for
| example.
| berdon wrote:
| Our two dogs watch our 4k TV often. And bark at various
| things, actors, subjects they don't like.
| Topgamer7 wrote:
| Had a dog that would press her nose right up to an ipad
| screen and move her face around to follow the squirrel,
| bird, or dog that interested her. She would get very
| excited about it. She also watched TV. At one point sitting
| on hind legs trying to elevate off the bed to be inline
| with the center of the image.
| bradstewart wrote:
| Only one of my dogs appears to recognize things in the TV.
| She'll bark at something on screen, and my other dog will
| run to a window or door trying to figure what he missed.
| Always wondered why...
| joshspankit wrote:
| I'm very suspicious of this 75Hz number. We've also heard
| that 60Hz is the limit of human perception but I think we all
| know now that we actually perceive higher than that (seeing
| flicker at 120Hz, blind A/B testing of 240Hz monitors, even
| perceptual flickering for some people in 1000Hz PWM LEDs).
|
| Even if that 75Hz number were derived from deep understanding
| and measurement of the entire visual pathway, there are
| variations in perception for people, there most likely are
| for dogs as well.
| Someone wrote:
| The limit depends on the size of the source, contrast,
| location on the eye of the source (rods are much 'faster'
| than cones, so we see flicker better out of the corners of
| our eyes), and probably a few other factors.
|
| 1000Hz I find hard to fathom, though. Would want to see
| what these signals look like.
| ColanR wrote:
| And don't forget about harmonics. Seems like flicker at
| higher refresh rates would happen whenever the mental and
| external rates synchronize.
| waiquoo wrote:
| 60Hz is the 'flicker fusion rate', meaning if you were
| changing the frequency of a flashing, stationary LED, ~60Hz
| would be the frequency where perception transitions from
| visibly flickering to apparently continuous. It's a lower
| threshold for refresh rate in the human eye. When you have
| complex refreshing images (a 2d computer screen rather than
| a point-like LED, diverse motion, depth, etc), you are
| likely to notice flickering (or tearing, jittering, non-
| smooth motion) if the refresh rate is near this minimum.
| barrkel wrote:
| People routinely watch movies which refresh at 24Hz and
| motion is apparently continuous.
|
| Perceiving flicker has a higher threshold. I can perceive
| 60Hz flicker in my peripheral vision easily enough.
|
| Other sources online (you can find lots of them but I
| didn't see an obvious authoritative article) suggest that
| 16Hz is the flicker fusion rate for motion in humans.
|
| Flicker fusion for continuous brightness (CFF) is
| somewhere around 30Hz per
| https://www.nature.com/articles/s41598-017-15034-z and it
| rises with brightness - this paper is about testing how
| it changes in different circumstances.
| svachalek wrote:
| Unless the camera moves fast and then it looks like a
| slideshow. Whenever they pan across a landscape it makes
| me grit my teeth.
| mdpye wrote:
| This is often exacerbated horribly by the fact that the
| 50 or 60 FPS output doesn't divide well by the 24 FPS
| source material. It was smoother in the cinema, when it
| was projected at 24 FPS...
| [deleted]
| Someone wrote:
| https://en.wikipedia.org/wiki/Flicker_fusion_threshold.
|
| Classical 50/60Hz lighting looks like a stroboscope to
| chickens. There is a whole field of research on the effect of
| light regimes, light color and flicker on poultry farming
| efficiency. I couldn't find a scientific link, but see
| https://agrilight.nl/lichtadvies/pluimvee/?lang=en&-en
| scarejunba wrote:
| That is just the stroboscopic effect. It's an artifact of your
| measuring tool. I'm not saying that your lights aren't
| flickering but your tool is introducing a lot to this system
| and so you can't use it as evidence.
| tasogare wrote:
| Philips bulbs are also at least twenty times more expensive,
| which is a lot of money for a light bulb.
| spdustin wrote:
| I have three weighty Philips bulbs mentioned in the teardown
| as carriage lights on the exterior of my house. They've been
| on 24/7 for maybe seven years now.
| codereflection wrote:
| True, however they are worth the price. I used various brands
| of LED bulbs for a long time (such as Cree), basically
| whatever Home Depot was selling. The failure rate was
| extremely high. In 2017 I switched to Philips LED bulbs, and
| just last night the first one failed. Overall they are worth
| the extra up front cost, they'll save you money in the long
| run.
| hocuspocus wrote:
| You don't need to buy Hue... Their 8W 800lm bulbs are EUR4 a
| piece in Europe, and a lot less in bulk. So 4x more expensive
| at worst.
|
| Philips' discount brand (Attralux) is even cheaper, I
| recently bought more of these 8W 800lm for less than EUR1 a
| piece. For now I cannot tell the difference.
| Junk_Collector wrote:
| This is actually a pretty big deal if you work with high speed
| or rotating machines. Using an high flicker LED bulb over your
| lathe (for instance) can cause it to appear static when it is
| in fact running due to visual aliasing. There are lines of
| flicker free LED bulbs for industrial spaces for this reason.
| altcognito wrote:
| At five times the cost, they had better be higher quality
| bulbs. $13 is pretty steep for a single bulb.
| derefr wrote:
| It's not like these bulbs are flickering in a way you can
| perceive _just_ by slowing it down by 2 /3/4x. They're
| flickering at 10000+ Hz. The reason cameras perceive the
| flicker is that they take discrete samples, with an (electronic
| or optical) shutter in between. This creates a _beat frequency_
| with things that also flicker, in effect "tuning into" a HF
| flicker and "lowering it" into the visible range, the same way
| a superheterodyne radio tunes into a HF carrier wave and brings
| it down into the audible range.
| Robotbeat wrote:
| Filament LED bulbs usually flicker at 120Hz (with high duty
| cycle) and Christmas LEDs at 60Hz (with a short duty cycle).
| Other LEDs are, indeed, high frequency like you describe and
| are perceptually effectively constant.
| vidanay wrote:
| The filament in a filament bulb doesn't fully cool down
| when the voltage crosses to zero, so that smooths them out
| a lot.
|
| Sorry...I just noticed you are talking about filament LED
| and not old fashioned analog filament bulbs.
| ubercow13 wrote:
| Some bad LED bulbs flicker so slowly you don't even need to
| video it, you can just tell when you walk into the room
| smoyer wrote:
| Yep ... it's the digital (meaning on-off) version of the slow
| moving line you see if you point your camera at a TV (or
| computer) screen - the speed that it happens at is the sum
| and the difference of the two frequencies (and perhaps at the
| sum/differences of their harmonics).
|
| In the CATV industry, we used to send 110 analog channels
| across roughly 800MHz of spectrum (54MHz to 860MHz). Other
| than background and ingress noise, a major source of noise
| (effectively) was distortion - non-linearities in the
| amplifiers that kept the signal at a reasonable level.
| Composite Second Order (CSO) and Composite Triple Beat (CTB)
| distortions were two values that equipment transporting these
| signals would generally call out - they are analogous to the
| summing and differencing of two signals and three signals
| (respectively) as described above for the lightbulb, but
| imagine doing that with 110 different frequencies
| simultaneously.
| pwg wrote:
| The 10khz+ flicker only comes about if the bulbs have a
| proper switching power supply (and if that switching power
| supply itself runs at 10khz+).
|
| But for the 'real cheap' bulbs, they likely (due to being
| "real cheap") have either a half wave or full wave rectifier
| (i.e., no switching PSU) which results in the LED's having a
| flicker at power line frequency (either 50hz, 60hz, 100hz, or
| 120hz depending upon which combination of line frequency and
| full/half wave rectifier is present).
| nicolaslem wrote:
| Now that incandescent bulbs are almost gone, I wonder if it
| will become common to have wires carrying DC in the ceiling
| instead of every bulb having to implement the AC to DC
| conversion as cheaply as possible.
| andruby wrote:
| Then we can also use this for our video camera's and
| wireless access points. Maybe we can add network to those
| cables. Let's call it "power over ethernet" ;)
| elFarto wrote:
| Ubiquiti has got you covered:
|
| https://unifi-led.ui.com/
| 205guy wrote:
| With renewable energy and local batteries, it would make
| sense to have DC wiring. It used to only be that off-grid
| systems had batteries (usually lead-acid), and they
| always just use an inverter. But now with battery packs
| such as the Tesla Powerwall, even grid-connected houses
| have DC storage.
|
| Unfortunately, Powerwalls and other similar products are
| made with built-in inverters and connect only to AC,
| there is no DC tap. And there aren't any standards around
| DC wiring and small appliances, so it isn't likely to get
| traction.
|
| I'm mentioned before
| (https://news.ycombinator.com/item?id=21109247) that I've
| seen a DC installation at a friend's house, he used 12V
| cable lights and DC bulbs, so it seems to work.
| zaroth wrote:
| I have DC powered under-cabinet lights which are
| definitely flickering at some fairly high rate.
|
| Imperceptible if you are just looking at it, but in a
| dark room if you move something quickly in front of it
| you can see the strobe effect.
| 205guy wrote:
| But where is the DC coming from? If it is a cheap power
| source, the DC into the lights could be intermittent, and
| so cause flicker.
| kps wrote:
| The real cheap filament style bulbs _are_ a rectifier, and
| nothing but.
| spookthesunset wrote:
| I guess you are right about the beat frequency bit, but I
| still assert that the cheap LED's are cycling on and off 60
| times a second (or 30.... math is too hard early in the
| morning). That is a bit low for my taste.
| seiferteric wrote:
| Take a battery, photo-resistor and a capacitor and hook up
| to headphones in series and you will be able to hear your
| bulbs flickering.
| mrb wrote:
| No, as reported by other posters, most bulbs that flicker do
| it at 120 Hz or 60 Hz. This is easily confirmed by eyesight
| alone because 60 or 120 Hz can be perceived when an object
| illuminated by the bulb moves in front of a dark background.
| syphilis2 wrote:
| I have 960 fps video of some LED bulbs in my house. It's very
| apparent that some bulbs do not flicker (perceptibly), some
| flicker at 120Hz, and some flicker at 60Hz. At night I can
| sweep my eyes across the bulbs and see the dashed lines
| resulting from them turning off and on.
| hinkley wrote:
| I used to be able to detect the flicker by eye, or sometimes by
| waving my hand. But they pack so many into the demo display at
| the store that when I moved I had to use the slomo feature of
| my phone to pick the right LEDs.
| tyingq wrote:
| I don't know about the bulbs, but commercial LED drivers from
| companies like Meanwell typically let you select a range
| between 100Hz and 1000Hz for the PWM frequency.
| Robotbeat wrote:
| The filament bulbs are almost all like this. Not too bad if
| they're using an H-bridge (120Hz with high-ish duty cycle), but
| Christmas LEDs I think might use no separate diodes at all,
| just relying on their own diode-ness. That means they're 60Hz
| with a less-than-50% duty cycle.
|
| Filament LED bulbs (the ones that look almost exactly like
| clear incandescent bulbs with a visible filament when turned
| on) do this because they have to fit their electronics in the
| tiny metal base. Room enough for some diodes (and maybe a
| capacitor), but usually not a full set of high frequency
| switching electronics like in most other LED bulbs (although
| I've seen some filament bulb tear downs that might show more
| advanced electronics). But again, doesn't bother me due to
| their high duty cycle and relatively okay refresh rate.
|
| (At least, this is all my impression. Please correct me.)
| gumby wrote:
| > On a side note I sometimes wonder if other animals have a
| quicker "refresh rate" on their eyes.
|
| Indeed, to the housefly, an incandescent-bulb-lit house slowly
| pulses from light to dark, so probably too with cheap line
| voltage choppers.
| SamBam wrote:
| > an incandescent-bulb-lit house slowly pulses from light to
| dark
|
| This sounds amazing to me, but also confusing. My
| understanding is that an incandescent bulb works entirely by
| heating up the filament. There should be no way that the
| filament is cooling down and heating up in anywhere close to
| the rate that it would require to get some kind of wagon-
| wheel effect, which is what it sounds like you're describing.
| pwg wrote:
| Ignoring 'complex power' concerns, the AC voltage driving a
| tungsten filament bulb is a sine wave at line frequency
| (60hz for the US). Because it is a sine wave, and because
| the tungsten filament is a resistor, the current through
| that resistor rises and falls in sync. with the AC sine
| wave. The current will be zero at the zero volt crossing
| point of the wave, and maximum at the peaks of the
| sinewave.
|
| The varying current through the tungsten will result in a
| varying power consumption (varying at a 60hz rate). The
| varying power consumption will result in a small amount of
| varying temperature on the filament.
|
| Now, the filament does not cool down instantly, so the
| result is its temperature will vary by a few degrees, but
| likely not enough to ever be perceptible to human eyes. But
| with a sensitive enough (and fast reacting enough)
| temperature probe, one could likely measure the temperature
| rise/fall of the filament that is synchronized with the
| line frequency.
| SamBam wrote:
| Right, the wave filter effect caused by the thermal mass
| of the filament was my point.
|
| I'm not sure you've shown that this would be visible to a
| housefly as a "slow pulse from light to dark," as the
| post I was replying to claimed. First of all, you said
| the power consumption will vary at a 60hz rate, but it
| seems to me it will vary at a 120hz rate, since the
| current will be at its max magnitude twice per cycle (as
| you say in the first paragraph). But more to the point, I
| don't know whether the temperature/lumens will decrease
| enough in 1/120th of a second to be visible to houseflies
| or anything else.
|
| Trying to research the answer, I found this physics lab
| worksheet [1] from Pasco (the makers of sensors), for a
| high school lab measuring the output frequency of
| incandescent bulbs vs fluorescent bulbs, but without
| doing the lab I don't know the results.
|
| 1. http://phylab.yonsei.ac.kr/exp_ref/pasco/P54_BULB.pdf
| whatshisface wrote:
| Incandescent bulbs store thermal energy in the fillaments,
| lowpassing the signal in the same way as a capacitor would on
| an LED bulb. A 60Hz flicker would be perceptible and if
| incandescents had that problem nobody would use them.
| zadler wrote:
| If that were the case I wonder if there is a frequency which
| the fly's vision has a hard time adapting to.
| throwanem wrote:
| Likely. As with dragonflies, there is a minimum speed below
| which flies don't perceive motion. In both cases, if you
| move very ( _very_ ) slowly, you can approach almost to
| physical contact without provoking any reaction.
|
| Anecdotally from my experience as a macro photographer, the
| threshold for flies is lower than for dragonflies; flies
| often startle in response to movements almost too tiny to
| perceive having made, while dragonflies are relatively
| easy, usually requiring only a few minutes to approach from
| a distance of a meter or so to the ~12cm minimum focus
| distance of my best macro lens. (It's hard to know; the
| passage of time isn't of much interest in the focused flow
| state that's required for this sort of activity.) It helps
| that disturbed dragonflies tend much more often to return
| to the same perch, but with some practice it's possible to
| make the entire approach without disturbing them at all.
| The only really tricky part about it is that, when you're
| moving slowly enough, they also tend to land on _you_ ,
| which can be somewhat distracting if you're ticklish.
|
| In any case, the existence of a minimum rate of change for
| perception of motion suggests that flickering light below a
| certain frequency might well be perceived as strongly
| discontinuous.
|
| (It also merits mention that my macro rig includes three
| very powerful flash heads mounted around the lens front
| element. I've never observed dragonflies, wasps, bees,
| flies, or spiders to react to these in any way, even when
| firing from a distance of six inches; the only reaction
| I've seen has been from fall webworm caterpillars, which
| displayed a communal defensive response, and that may have
| been as much due to the shadow I cast, or to the polistid
| wasps hunting nearby, as to my flashes firing. The wasps
| notably did not care at all about me or my flashes,
| especially after they also found the nest and busied
| themselves with its rapid depopulation.)
| UnFleshedOne wrote:
| We used to catch them by the wing by slowly approaching.
| Interestingly, medium ones were easy, but the big ones
| (different species, much rarer) wouldn't let me approach
| at all.
| throwanem wrote:
| I mostly encounter eastern pondhawks and Halloween
| pennants, which are medium-sized and typically easy to
| approach.
| tootie wrote:
| My cheaper LEDs also seem to get destroyed by a dimmer much
| quicker than better ones. Not sure if that's related.
| indiantinker wrote:
| $1.25? How about a 60c LED light bulb teardown
| :http://rohitg.in/2014/10/28/Dollar-LED-Bulb/
| petercooper wrote:
| If, for some reason, lighting teardowns are a fascination of
| yours, I thought I should mention "bigclive", a YouTube channel
| devoted to this very topic :-D
| https://www.youtube.com/user/bigclivedotcom/videos (the author of
| this blog post also has a channel at
| https://www.youtube.com/user/electronupdate/videos )
| ASalazarMX wrote:
| Never expected to see cheese and electronic teardowns mixed.
| jcims wrote:
| Indeed!
|
| Also https://www.youtube.com/user/mikeselectricstuff/videos for
| lighting and scrap medical/industrial equipment teardowns.
|
| If you are into RF dark magic,
| https://www.youtube.com/user/TheSignalPathBlog/videos for
| teardowns (and repairs!) of GHz scopes, network analyzers, etc.
| politekc wrote:
| "Hi!" Don't forget EEVblog!
| https://www.youtube.com/user/EEVblog
| crmd wrote:
| It put a big smile on my face that big clive is the first
| comment here :-) His videos are hypnotically good! He's tied
| with aVe IMO as the best teardown channels on youtube.
| Scoundreller wrote:
| But only one of those two is family friendly :)
| gwbas1c wrote:
| > A fused neutral design would leave all of the bulb electronics
| hot. Strange.
|
| Makes me wonder if the resistor is really a fuse?
|
| BTW, I recently bought a plug -> bulb adapter on Amazon. It did
| not preserve neutral at all, and instead had a higher plastic
| ridge making it impossible to touch the metal part of the bulb.
| (The part that's at risk of touch, so it's typically connected to
| neutral.)
| gvb wrote:
| No, it is not a fuse. It is most likely there to limit the
| inrush current into the cap when the power is applied.
| jacob019 wrote:
| I have often seen resistors used as fuses in cheap designs, but
| I have never seen a wirewound resistor used in this way. It is
| for current limiting to reduce peak load on the cheap
| components. Although it would probably be the next thing to
| blow if the IC failed short.
| pfdietz wrote:
| The best thing about this bulb is that it isn't some internet-
| connected abomination.
| Someone1234 wrote:
| I'll take my "internet-connected abomination" over having to
| wire in a dimmer switch that might change the tone of the light
| as you dim, make buzzing sounds, cut out the light early, or
| shorten the lifespan of the bulb.
|
| Hue has been the first dimming system that actually works well.
| I have a few colored bulbs, but rarely need them, the biggest
| benefit to me (aside from automation: dusk auto-on/off) is
| dimming different shades of white/yellow. Great system that has
| no real analogue competition.
| kawfey wrote:
| As an amateur radio operator, I can hear the RFI generated from
| that cheap bulb just by looking at it. I upgraded my home from
| CFL to LED and found out the hard way that cheap IKEA bulbs are
| not conducive to a radio hobby. Philips Hue and Lifx have been
| generally much better.
| tigeba wrote:
| I recently replaced a bunch of bulbs in my recording studio
| with LED and it was a huge mistake. They are basically RFI
| cannons. I removed them after realizing what was going on. I
| spent a couple of days hunting down a really nasty rogue noise
| and it ended up being a LIFX bulb I had forgotten about. Now I
| have to find a huge pile of black market incandescent bulbs...
| wglb wrote:
| Not all LEDs are so good. I have under-the-counter LED lights
| that total the low bands when turned on.
| ericol wrote:
| In my experience, the electronics _around_ the leds tend to fail
| rather fast.
|
| Few years back - around 7 - we expanded our house slightly (A
| room, a small living room and a small bath) so I put led bulbs in
| there, plus I replaced some of the bulbs in the rest of the
| house.
|
| As I bought several of these (5+) when I placed them I wrote on
| them with a permanent marker the date of installation. Bear in
| mind these were not extra cheap, more like mid priced ones.
|
| 6 months from installation I had to start replacing them, and at
| the 18 months mark I had replaced most of them.
|
| Bear in mind this coincided with a big legislation in my country
| that made "normal" light bulbs illegal (Because ecology, global
| warming and shit).
|
| I doubt they took into account how much trash these cheap bulbs
| generate.
|
| Also, whatever money you save from less energy consumption is
| probably a lot less than the money that it costs replacing them
| this often.
| burgerquizz wrote:
| Hijacking the comments. I have a project that would involve about
| 15+ smart Lightbulbs. Anyone would know any decent/cheaper
| alternative to the Phillips Hue bulbs?
| vassie wrote:
| These videos compare a few on offer...
|
| https://www.youtube.com/watch?v=osauwVoP4a8
|
| https://www.youtube.com/watch?v=-ZPo7C3PDT4
|
| I also highly recommend the Smart Home Solver YouTube channel
| if you're interested in home automation
|
| https://www.youtube.com/channel/UCwOBG77Tm8cE24FPxHb_abw
| Klathmon wrote:
| Think outside the box (outside the bulb?)
|
| z-wave "behind the switch" modules are super easy to install
| (you pull out the switch on the wall, and you put a small box
| in between the switch and the mains wiring), and you can
| control a whole circuit with one ~$40 switch. Depending on
| which one you get, they also support 3 and 4 way circuits
| (although with some caveats).
|
| And it comes with the additional benefits that it will always
| work with the manual switch (turning it off or on), and it will
| work with any lightbulbs you may want to use in the future, but
| the downside is that you can't really get full RGB colors in
| the bulbs if that's something you are going for.
| rootusrootus wrote:
| This is more or less my preferred solution. I use z-wave
| switches, not modules, though. I don't get RGB control, but I
| do get home automation that fails gracefully back to "works
| just like a light switch always did" if something goes wrong.
| somehnguy wrote:
| If you need discrete bulbs (vs a strip) the Merkury brand sold
| at Walmart have been working great for me. $20 for 2 full color
| lightbulbs vs $50 for 1 Philips Hue.
|
| They operate on 2.4ghz wifi and after inspecting the traffic do
| not appear to be funneling my data to China.
| semi-extrinsic wrote:
| If you don't mind a bit of custom work, FastLED and WS2812 LEDs
| is where it's at.
|
| Evilgenius has a level shifting board for the ESP32 or ESP8266
| that takes a lot of the hassle out if you need many separate
| patterns.
| Galanwe wrote:
| Do you have to control the bulbs individually? Do you need to
| address (talk to) the bulbs individually? Are the bulbs far
| apart or close one to another?
| Slartie wrote:
| Can't speak about the quality of the "smart" parts in
| particular, but the Ikea LED bulbs have proven to be of
| generally high quality for a good price. I have a bunch of them
| in operation, and had some in permanent use (powered 24/7) for
| years now. Only a single bulb has failed on me after 4.5 years
| of continuous use, and even that bulb failed gracefully (it
| became darker and darker over time, while getting hotter and
| hotter, obviously converting more energy to heat than light).
|
| Hence I would not hesitate to give their smart bulbs a try as
| well, assuming they use the same circuitry and LEDs for the
| "non-smarts" of the bulbs as for all the others.
| rootusrootus wrote:
| One thing to consider with the Tradfri bulbs is that some
| people (myself included) have experienced them turning on
| randomly. Internet says it might have something to do with
| automatic software update, but that is hearsay.
|
| Also, for a smart bulb I find their control requirements to
| be weird. Pair with this device first, but only up to X
| devices, then pair that with the hub. Everything else I have
| is Z-wave so maybe this is par for the course for smart bulbs
| and I'm just not used to it.
| stordoff wrote:
| I think there's a way to pair them directly with the hub. I
| did it recently when I only bought a hub and outlet (no
| remote)[1], and it worked fine. One rumour I've seen a few
| times is that the Hub was an afterthought[2], which is why
| it is designed around pairing with the remote, but it's
| definitely a weird setup (they're ZigBee, so should work
| without the remote - they do when using the Hue hub).
|
| [1] https://www.reddit.com/r/tradfri/comments/bddyjt/connec
| t_tr%...
|
| [2] https://www.reddit.com/r/tradfri/comments/aq0161/pairin
| g_wit...
| StapleHorse wrote:
| Try searching for slamper. It's a "smart" E27 socket. You can
| flash its ESP8266 to do whatever you want.
| mlonkibjuyhv wrote:
| Check Ikea
| scarejunba wrote:
| Get a power strip, WiFi plugs, and normal lamps.
| lgleason wrote:
| If you want to go with LED strips there are a lot of options
| that are cheaper and better. Actual bulbs are a bit trickier.
| tinus_hn wrote:
| Ikea Tradfri is slightly less polished but much cheaper than
| Hue.
| ChuckNorris89 wrote:
| Xiaomi Yeelight
| joshspankit wrote:
| Depends how much you care about brightness, light frequency
| (aka how "pleasing") and flicker.
| ThePhysicist wrote:
| It's pretty amazing how powerful small chip-on-board (COB) LED
| modules have become. I recently built a 6000 Lumen aquarium light
| with 7W - 850 Lumen COB modules. The active surface is just 5x5
| mm, so the illuminance when held in front of your eye (1 cm2
| surface) is about 17.000.000 Lux, roughly 100 times brighter than
| direct sunlight on a summer's day at noon (so don't do it as it
| might be the last thing your see with that eye). And those
| modules are actually at the low end of the available power, you
| can get up to 35 W packaged into such a tiny COB, which is just
| crazy. Good thermal anchoring of the chips is therefore
| paramount, as they will quickly heat up to the point of being
| destroyed by electromigration if they're not properly cooled (and
| I imagine for the control electronics in the light bulb the high
| temperatures are also not beneficial). Anyway, it's still
| impressive how much light you can get out of such such tiny
| devices.
| bprater wrote:
| This has impacted the video production business in a positive
| way over the last couple years. Previously, we had to put on
| gloves, find a 30 amp fuse and use hot tungsten lights to put
| together a production. Now folks are using high-quality LED-
| based lighting, running off battery power, and significantly
| smaller than a generation ago.
| JohnJamesRambo wrote:
| I find teardowns like this fascinating. Especially in designs
| that are trying to do things as cheaply as possible.
| msisk6 wrote:
| You'll probably like the product teardowns of youtube user AvE.
| He usually does tools, but also the random appliance or product
| from time to time. His teardown of the Juicero is a classic:
| https://www.youtube.com/watch?v=_Cp-BGQfpHQ
| Animats wrote:
| Some designs eliminate the electrolytic capacitor. That's the
| first component to fail. If you want 10+ years of operation, it
| has to go. You can get rid of the electrolytic, but you have to
| add an inductor.[1]
|
| [1] https://led-driver.power.com/products/product-
| archive/linksw...
| WrtCdEvrydy wrote:
| I love seeing designs that fail while keeping the product as
| electrically hot as possible - said noone ever.
| ygra wrote:
| Oh, Big Clive might say something to that effect, I'm sure.
| Zod666 wrote:
| Not knowing much about less, are any of these cheap ones just as
| good as the premium ones? I'd also like a bulb that could be
| changed to an orangish hue at night to block out blue light. From
| what I read a lot of them emit little light when changed to
| orange.
| JoshGlazebrook wrote:
| Does anyone know where to find actual good LED bulbs? All of the
| Feit bulbs from Costco I bought eventually died within two years.
| I tried buying Phillips (non hue) off Amazon, and they are also
| starting to die in about a year to a year and a half. They really
| try to sell LED bulbs as lasting "forever", but in reality they
| seem to die just as fast.
| audunw wrote:
| Maybe there's some problem with the voltage in your house? I
| have never ever experienced an LED bulb dying on me, not even
| dirt cheap ones.
| rootusrootus wrote:
| Could also be fixture choice. My Feit can lights from Costco
| have had a couple failures so far, a few years after I bought
| them, but mostly when I have an LED bulb fail it's been in
| one of my enclosed fixtures. That's my choice, though, I take
| the risk. I buy decent quality bulbs, but I like them bright
| so I end up with 1600 lumen bulbs in an enclosed fixture,
| which is toasty. They only last a couple years before
| malfunctioning. Sometimes I can get more time out of them by
| moving them to table lamps.
|
| I monitor the electric service at my house and it's very
| steady at 240V.
| ptmcc wrote:
| I replaced the mish mash of bulbs in my house with all GE
| "Reveal HD" LED bulbs of different temperatures. Nothing super
| fancy, just name brand hardware store bulbs.
|
| In the variety of old bulbs, the Feit ones in particular were
| causing issues with dimmers and also getting slightly
| discolored and buzzy. Only one had outright died, but seemed
| that more were on their way.
|
| All the new GE ones have been great so far (only a year), but
| I'll let you know in 10 more years.
|
| Refreshing all the lighting in the house with modern, matching,
| actual-dimmable LED bulbs (along with nice dimmer switches) has
| been a really nice ambiance upgrade.
| snapetom wrote:
| I've had good luck with Cree, Home Depot's brand. I don't think
| any of them have died since I converted about five years ago.
|
| Lowe's is stocking GE these days, but I'm not familiar with
| their quality. The reason I'm not familiar is that they
| exclusively stocked Feit initially, and yes, those things are
| pure garbage. They had high failure rates and were not "instant
| on" compared to others. I stopped buying them and switched over
| to the Home Depot brand.
| mceachen wrote:
| Just another speck of anecdata: I've had to replace almost
| all of my < 10 years old, <~10k hours of use Cree bulbs. The
| last 5 years of LEDs (feit, Cree, GE) haven't failed yet.
| spdustin wrote:
| The Cree LED bulbs I had years ago had a major buzzing
| problem. Do you feel like that's still an issue?
| geerlingguy wrote:
| I've tried a few of the GE bulbs over the years, and the
| quality and CRI is always not that great (sometimes easy to
| tell by taking photos with a good camera and seeing how
| little color you can get out of certain channels). Cree bulbs
| have always been pretty good, and Phillips bulbs have been
| the best.
|
| There are a few other brands you can get online that have
| better rendering (CRI), and are more accurate to the stated
| color temperature over time, but they cost sometimes double
| what even the Philips bulbs cost.
|
| I also wanted to add a data point that I've switched every
| light in our house to LEDs over the past decade, and only had
| two bulbs (out of maybe 50+) fail in that time--both were in
| outdoor fixtures which range from 10-100% humidity, and
| -10degF to 110degF through the year (quite a torture test).
| Shivetya wrote:
| one other concern not mentioned by others, vibration. this can
| come from being too close to a door or being mounted on
| something with moving parts, ceiling fans and garage door
| openers.
|
| Also tulip like lamp shades where the base is at the top can
| concentrate heat and wear the electronics down; canister mounts
| do the same if no venting.
| ASalazarMX wrote:
| I've found cheap LED bulbs fail faster when used in ceiling
| fans. Some soldering points can break with vibration.
| scarejunba wrote:
| It's probably a result of the fixture. You need sufficient air
| flow to dissipate heat or they fail pretty fast.
| Someone1234 wrote:
| You might want to check your home for electrical issues
| (specifically spikes). I've yet to have a single LED light bulb
| die ever, some have already exceeded their supposed 10 year
| lifespan.
|
| And that's not one brand. I have GE bulbs, Philips (Hue and
| not), and random brands from Amazon.
| 0xff00ffee wrote:
| Same here. I put 2700K philips all over my house 5 years ago
| and I haven't had any issues, but I have no idea of the
| quality of the power coming into my house from my provider.
|
| (Anyone know how good Austin Energy's electricity on the west
| side is?)
| JoshGlazebrook wrote:
| This is at two separate apartments, and a standlone house.
| All of them seem to die.
| amiantos wrote:
| Gotta check your attitude, maybe it's disrupting the
| DeKalbs. (Sorry for the Heinlein reference, it was too
| tempting.)
| bcrosby95 wrote:
| Were they selling cheap LED bulbs over 10 years ago? By my
| recollection they were all expensive back then. It seems
| plausible yours were expensive and higher quality than all
| the cheap ones everyone is buying nowadays.
|
| Speaking for myself, I've bought a variety of brands over the
| years. Some brands seem to die after a year or so. Others are
| still going fine after 3-5 years.
| baybal2 wrote:
| > A fused neutral design would leave all of the bulb electronics
| hot. Strange.
|
| Depends on what country you are living in.
|
| It's not new for me to see a product passing safety certification
| in one country, failing in another, but still ending up in it
| because of messup by people running the OEM industry.
|
| Second to it, in a normal country, for an electrical appliance,
| failing short, and triggering a short circuit protection is a
| relatively safe alternative to having a dedicated fail safe
| circuit, but in countries with building codes not saying anything
| about wiring safety, it often means a fire.
| cotillion wrote:
| Considering how popular unpolarized plugs are all over the
| world I don't think a fused neutral is much of a problem in a
| lamp.
| tinus_hn wrote:
| Anyway European Schuko plugs are not even polarized, there is
| no way to know which wire is hot.
| gwbas1c wrote:
| Honestly, I think it's better that we view polarization as a
| historical oddity. So many people don't understand the
| concept.
|
| Even I have trouble understanding the real difference between
| ground and neutral, because neutral connects to ground in the
| breaker panel. I'm not even sure if neutral goes through the
| breaker?
| pwg wrote:
| Note, the below will be for the US -- rules will be
| different in other countries.
|
| > Even I have trouble understanding the real difference
| between ground and neutral,
|
| Neutral is the normal return path for current. Under normal
| operation power is delivered to a device via the "hot"
| conductor, and travels back from the device to the source
| over the neutral conductor.
|
| The ground conductor is present for safety purposes. Under
| normal operation no current should flow over the ground
| conductor at all. The only time the ground should have a
| current flow is during a safety event (i.e. a short from
| hot to the case of a device with a metal case).
|
| > I'm not even sure if neutral goes through the breaker?
|
| It does not, the breaker is present in the "hot" conductor
| path, and tripping the breaker disconnects just the hot
| conductor from the power source.
| BlueTemplar wrote:
| Power flows opposite current, doesn't it?
| pwg wrote:
| I've never heard of that description in all my years as
| an EE. Do you have a citation or reference to that
| description?
| sunstone wrote:
| Power = I^2*R so power is positive regardless of which
| way the current is flowing. (rms current in the case AC,
| not accounting for power factor)
| rootusrootus wrote:
| The neutral handles the expected load, while the ground is
| designed specifically to be an alternate current path from
| the case (assuming it is conductive) that has low
| resistance and will immediately flow enough current to trip
| the breaker in case the hot somehow comes into contact with
| the case.
|
| Neutral does not go through the breaker, correct.
| ars wrote:
| Neutral exists separately from ground only because if there
| is some residual resistance in the line, there will be
| voltage on the neutral.
|
| So you have a separate ground that normally sees no voltage
| at all.
|
| You are correct, the neutral does not go through the
| breaker. It is usually wired inside the breaker panel
| though.
|
| Some localities want the neutral and ground wired
| separately (to separate bus bars), with a single point
| connecting them, but most don't care and the neutral and
| ground are attached to the exact same place inside the
| breaker panel.
|
| Electrically, the neutral and ground are at the same
| potential, assuming magic wires with zero resistance, but
| in the real world the wire does have resistance, especially
| if it was poorly installed, so they are not always at the
| same potential. There could also be capacitance in the
| line.
| zAy0LfpBZLC8mAC wrote:
| The purpose of separate wires is twofold:
|
| 1. It's to provide protection in case of neutral failure.
| If you have an appliance with the case grounded via neutral
| and the neutral wiring fails, you now have the case
| connected to live (through any appliance that is switched
| on). With separate ground, nothing happens as you are only
| allowed to connect ground to neutral at a point where
| failure of the upstream wiring is practically impossible
| (i.e., wires so thick that they practically won't break).
|
| 2. It's to provide a path for ground fault currents that
| does not pass through the RCD, if you have an RCD. While
| neutral doesn't go through the circuit breaker, it does go
| through the RCD, so as to measure the difference in current
| between live and neutral. If your appliance is grounded
| vial neutral, any ground fault (connection from live to the
| case) looks like regular load current to the RCD, if it is
| grounded via separate ground, the fault current bypasses
| the RCD and thus causes it to trigger, even for a small
| current that would not trigger over current protection.
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(page generated 2020-02-19 23:00 UTC)