What light blubs should I use? - Page 1
Forum section: electronics / beginners

author: eeguy
author_rank: Regular Contributor
timestamp: July 21, 2022, 01:50:05 pm
content: Hi, I need to replace all fur light bulbs of a standing light. By "To reduce the risk of fire use 100 Watt Type A or smaller map", does that mean the total watt of four light blubs should be "100 Watt or less" or each light blub can be "100 Watt or less"? What is Type A?In the middle, there is another label saying that "To reduce the risk of fire, use Max 50Watt or smaller". So the middle one and the three on the sides have different requirements?(original lightblub that came with the light)Am I correct that the original light blub is 0.138mx120V = 16.56 Watt so four of them totals 66.24Watt which is below 100W?

author: mariush
author_rank: Super Contributor
timestamp: July 21, 2022, 02:00:42 pm
content: It's 9W light bulb. The current is probably higher because it's a switching power supply inside, it takes 120v AC and makes a lower voltage, and it may do so in bursts, so it may pull for brief periods of time 138mA worth of current from AC input.My guess is the 100w limitation is mostly about the thickness of the wires going from the bulb sockets to where you would actually connect to the house wires. Could also be about the heat but I doubt it, looks like it's all painted metal on the exterior.

author: themadhippy
author_rank: Super Contributor
timestamp: July 21, 2022, 02:19:27 pm
content: QuoteIt often is the heat ,cant remember the exact definition,but its all to do with the temperature rise over a certain time,or at least it was in the uk when i studied this stuff about 40 years ago.if it was to do with the wiring size here in the uk you'd have domestic fittings rated for 1200w lamps

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 21, 2022, 02:24:30 pm
content: For as far as I know, it is about the heat and not the current limit of the wires.Old fashioned light bulbs produce a lot of heat. This heat needs to be partially dissipated by the light fixture. (The air also takes part of the heat) With a bulb of more than a 100W in one of the sockets the heat might build up to much and start a fire.It is hard to say if the 100W is a total for the armature or per socket. The middle one having a label with 50W max suggests that it is per socket.With modern day LED bulbs you will be fine since even a 100W in total is hard to reach with these LED bulbs.

author: Zenith
author_rank: Frequent Contributor
timestamp: July 21, 2022, 02:57:10 pm
content: I'd assume it means each lampholder to have no more than a 100W bulb, and the centre one no more than 50W.Incandescent light bulbs got hot and the heat could degrade the bulb holder and cause it to crumble, and degrade the insulation on the wires. There were porcelain bulb holders and high temperature wiring, but a lot of light fittings used plastics and ordinary wiring. Airflow in the light fitting would be important. There may have been regulatory requirements for the design and requiring those warning stickers.If you are using modern LED bulbs at 10W each, it's not something to worry about.

author: MarkF
author_rank: Super Contributor
timestamp: July 21, 2022, 04:35:59 pm
content: The wattage limit is for each bulb and is there to restrict the amount of heat from each bulb. The low wattage of the middle bulb is probably because it is point straight down where the heat will go directly into the fixture.The wattage limit ONLY refers to incandescent bulbs. LEDs bulbs don't use never the same current as an old incandescent bulbs does. But don't be fulled, LED bulbs still get very hot.The LED bulb you've shown looks like a 60W equivalent LED. I would replace them with a 40W or 60W LED bulb depending on how bright you want to light to be. The bigger thing to look for is the light color temperature (i.e. appearance). You will want something around the 3000K (i.e. Soft White) as shown on your bulb. The 3000K'ish value will be the closest to an old incandescent bulb. Any of the bulbs listed as Daylight and/or having an appearance number of 4000K to 8000K are going to be a bright white to blueish tint and be vary harsh. Maybe you like that though.

author: Seekonk
author_rank: Super Contributor
timestamp: July 21, 2022, 04:57:00 pm
content: To add even more to the confusion. I saw a program where an electrician discussed this. He said it had to do with the house wiring and the temperature rating of the insulation of non metalic sheath wire. Before some time in the 70's the temp rating was lower. He stubbed in a new piece of wire and said you were good to go now.

author: tunk
author_rank: Super Contributor
timestamp: July 21, 2022, 05:11:49 pm
content: Heat is/was a problem:I recently replaced a lamp with two 11W G23 "bulbs".When unscrewing the screw connectors the plastic insulationcrumbled, and the cable insulation was brittle.Edit: About 30 years old, constantly on.

author: janoc
author_rank: Super Contributor
timestamp: July 21, 2022, 05:44:50 pm
content: Quote from: Seekonk on July 21, 2022, 04:57:00 pmIf a house wiring had a problem because of a 100W incandescent bulb then either the electrician was an idiot/charlatan or that was a really poorly and code-noncompliant built house ...Or someone is mixing a few different things up because house wiring does have max current rating. In Europe it is 10-16Aper outlet. That would make 2400-3800W of available power through that single wire. Maybe hooking up a lighting fixture with more than 24 100W bulbs could be risky ...Even at 120V and 15A in the US that's 1800W available. That should handle even a fairly large chandelier.The ratings on the fixtures is because of heat, as it was said above already, because the fixture could melt or even catch fire if the plastic softens. Nothing to do with wiring.

author: mariush
author_rank: Super Contributor
timestamp: July 21, 2022, 06:35:38 pm
content: I bought a cheap 30$ -ish "chandelier" thing with 3 bulb sockets (or whatever they're called) a couple years ago ... the cable inside the arms going to the actual sockets was made with strands of steel mixed with copper and if my memory is correct, it was around 0.5mm2in diameter... probably close to AWG22The recommended wattage was maximum 65w on each socket. So that's why I was saying that actually using bigger wattage bulbs could have overheated the insulation off those wires, not only from the current and wire resistance but potentially also from the cheap aluminum arms heating from incandescent bulbs heat.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 07:02:29 pm
content: The warning means exactly what it says, use 100W or smaller standard incandescent lamps. These days there is little reason to use incandescent lamps at all, so I would suggest using LED bulbs of whatever lumen output is sufficiently bright for your needs. 100W is around 1650 lumens, an LED bulb of that output will only be around 17 watts. The maximum wattage is because of the heat output, traditional incandescent bulbs turn about 95% of the energy they consume into heat.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 07:05:58 pm
content: Quote from: janoc on July 21, 2022, 05:44:50 pmNot necessarily. Remember this is a global forum, light fixture design and wiring standards vary from one place to another. I have seen wires melt from incandescent lamps in fixtures that were designed for lower wattage bulbs and concentrate the heat. Many fixtures also have multiple bulbs. I still need to replace the ceiling box in the hallway of my house, it is melted and deformed and the wires inside are darkened from somebody using excessively large lamps at some point before I owned it. It is a real problem, this is not the first time I've seen it.

author: Gyro
author_rank: Super Contributor
timestamp: July 21, 2022, 07:27:28 pm
content: Quote from: janoc on July 21, 2022, 05:44:50 pmThis might be an international thing, but your lighting circuits are 10-16A?In the UK, lighting circuits are fused at 5A (old) or 6A breaker, for a whole floor, sometimes a whole house, wired in 1 or 1.5mm2. I know the US is different, but I thought we were closer harmonised than that. The wire in most light fittings isn't good for 16A.

author: eeguy
author_rank: Regular Contributor
timestamp: July 21, 2022, 07:32:07 pm
content: The standing light is to be used in Canada. I found the light from the original light blubs a bit yellowish and dark. Are the following two light blubs OK?Am I correct that this has the same brightness as the original but in white color?https://www.ikea.com/ca/en/p/solhetta-led-bulb-e26-800-lumen-globe-opal-white-80509985/If I want brighter but OK with the original yellowish color, go for the following?https://www.ikea.com/ca/en/p/solhetta-led-bulb-e26-1600-lumen-dimmable-globe-opal-white-40510028/On the standing light, there is a knob where I can adjust the brightness. I guess there might be a variable resistor inside. Not sure. Why in a local Costco store, the LED blubs they sell are labelled as "non-dimmable"? Isn't the brightness of any light blub changeable if there is a variable resistor in the circuit?

author: janoc
author_rank: Super Contributor
timestamp: July 21, 2022, 08:46:44 pm
content: Quote from: Gyro on July 21, 2022, 07:27:28 pmI have 3 20A breakers for the kitchen and 5 16A breakers for the rest. There is no difference between lighting and outlets, in fact lights and outlets are on the same breaker (usually lights from one room with outlets from another). And this is a fairly old house, I think it was built in the 70s or so.You would be really hard pressed to find a house that uses less than a 10A fuse/breaker per circuit. It also isn't common to separate "lighting" and "outlets" to different circuits. It is usually mixed, so that if one breaker pops, you don't end up in complete darkness or only with lights and no outlets.In France it was similar, also in Denmark and Slovakia. Even though you could find some weird shit in some very old or very "DIY" installations.In the UK you have this strange ring-style wiring and fuses in the plugs, that doesn't exist anywhere on the continent.

author: Gyro
author_rank: Super Contributor
timestamp: July 21, 2022, 09:17:24 pm
content: I'll give you the "strange ring-style wiring", it is distinctly odd and going out of fashion (although there were strong economical and raw materials shortage reasons when it was defined), as has been discussed before. Lack of dedicated low current lighting circuits does seem equally odd though. Maybe they were also a consequence of the same shortages, I've never considered that - but given the price of Copper the reason seems as if it is just as relevant today (not to mention having to deal with unnecessarily thick Copper cores when installing ceiling roses (outlets)).We'll gift you the fused plug concept though, it saves an awful lot of hassle for things like moveable lighting and other low current appliances. You (the rest of the world) should try it.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 09:20:12 pm
content: Quote from: Gyro on July 21, 2022, 07:27:28 pmIt doesn't matter in this case, it isn't the power draw that damages the wires, it's the heat from excessively high wattage bulbs. Modern light fixtures have mandated clearances (which makes the classic bedroom and bathroom fixtures look stupid IMHO) but older ones did not. People would sometimes put high wattage lamps in fixtures designed for 60W max and the heat from the lamp(s) would melt things or in some cases start fires.As for the current, our lighting is often on shared circuits with receptacles, 15A circuits are almost always used for lighting and a mixture of 15 and 20A branch circuits feed receptacles. IIRC you can have 10 15A duplex (double) receptacles on a circuit.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 09:22:54 pm
content: Quote from: Gyro on July 21, 2022, 09:17:24 pmThe ringmain concept is strange and caught me off guard the first time I heard of it although I can certainly see the advantages it offers, along with some disadvantages.The fused plugs are a great idea and I'm frankly not sure why those haven't caught on here, they do exist for holiday lighting although those are not very robust and I've had the fuse contacts burn up on several occasions without the fuse blowing back when C9 incandescent lights were common. I quite like British 13A plug and use them for some 240V bench applications, they're very robust, the only real disadvantage is they are also very bulky which is problematic for power strips and such.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 09:30:43 pm
content: Quote from: eeguy on July 21, 2022, 07:32:07 pmYikes, no, not even close. A dimmer switch is not a variable resistor, well, the actual knob part usually is but they use a technique called phase control which varies the point at which a triac switches on each AC half cycle to control the average voltage. LED bulbs require a built in driver circuit to convert the constant voltage AC to constant current DC. Many of them are designed to work with traditional triac light dimmers to various degrees of success but many are not. You should never use a non-dimmable LED bulb on a dimmer, it's not going to burn your house down but it's not going to work right either and it will probably damage the bulb.You can use any LED bulb you want that will physically fit in the socket, except if there is a dimmer you need bulbs that are dimmable. Often you will find them marked with the incandescent equivalent wattage, for example 60W, and also the actual wattage which will be something like 6-9W. The two values that should really matter to you are lumens and color temperature. Secondary to that is CRI, the color rendering index. Incandescent lamps were bound by physics and came in only one variety, while LED bulbs are available across a wide range. The most common are 2700K (warm white, incandescent-like) and 5000K daylight which is a much cooler white. Cheaper LED bulbs are mostly 80 CRI but if you can find 90+ CRI those will make things look nicer.On the standing light, there is a knob where I can adjust the brightness. I guess there might be a variable resistor inside. Not sure. Why in a local Costco store, the LED blubs they sell are labelled as "non-dimmable"? Isn't the brightness of any light blub changeable if there is a variable resistor in the circuit?

author: themadhippy
author_rank: Super Contributor
timestamp: July 21, 2022, 09:39:31 pm
content: Quoteyep there will be ,but that variable resistor will be controlling a triac or some other electronic circuitryQuotea straight variable resistor then yes,but as its not then no,it all depends what type oflight bulblamp is being used,normal tungsten couldn't care less,discharge lighting tends to upset dimmers and with leds it depends on the type of driver circuit being usedQuotethey are,until you stand on one,it normally happens when your barefooted in the early hours of the morning.

author: james_s
author_rank: Super Contributor
timestamp: July 21, 2022, 10:03:34 pm
content: Quote from: themadhippy on July 21, 2022, 09:39:31 pmNot as bad as a TO-3 transistor, ouch.No reason a fused plug has to be the specific design adopted by the UK. Our standard NEMA-15 plugs could easily be made in a fused variety if someone bothered to do so. The only place I've ever seen one is on holiday lighting though where I believe it is mandated.

author: eeguy
author_rank: Regular Contributor
timestamp: July 21, 2022, 10:19:42 pm
content: Quote from: themadhippy on July 21, 2022, 09:39:31 pmSo using four of any of those two IKEA blubs I linked should be fine?

author: MarkF
author_rank: Super Contributor
timestamp: July 21, 2022, 10:58:34 pm
content: Quote from: eeguy on July 21, 2022, 07:32:07 pmIf the LED bulb says it is non-dimmable, it means NOT dimmamble.All LED bulbs have a small power supply inside.They will more than likely just turn off if you try to dim them because its internal power supply will just shutdown if the voltage drops too low.Edit: The two IKEA bulbs you linked to say they are 100W incandescent equivalent. Five bulbs will be very bright. I would look for 60W equivalent.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 22, 2022, 03:40:33 am
content: Quote from: janoc on July 21, 2022, 08:46:44 pmI don't know when or even if it changed, but when I started building the extension to our house in France 12 years ago, the regulations demanded separate circuits for lights and outlets. As a result we have lots of breakers spread across multiple breaker-boxes.10A fuse for light circuits with a maximum number of light fixtures connected. Forgot the number.16A or 20A fuse for outlets with a maximum number of 5 outlets for 1.5mm2 wires and 8 for 2.5mm2 wires. (Not sure if the numbers are for 16A or 20A)In the Netherlands the system seems to be the same as in Germany going by your description.

author: BrokenYugo
author_rank: Super Contributor
timestamp: July 22, 2022, 03:58:12 am
content: I suspect North America not having low current lighting circuits goes back to the real early home appliances that have a cord terminated with an Edison screw plug to go into a light socket.

author: eeguy
author_rank: Regular Contributor
timestamp: July 22, 2022, 02:00:10 pm
content: >The two IKEA bulbs you linked to say they are 100W incandescent equivalent. Five bulbs will be very bright. I would look for 60W equivalent.Each LED lightbulb with a rating anywhere 7 to 10 watt would be OK?

author: MarkF
author_rank: Super Contributor
timestamp: July 22, 2022, 02:23:40 pm
content: Quote from: eeguy on July 22, 2022, 02:00:10 pmThe power rating of LED bulbs is meaningless as to how much light they put out.LEDs use so little power that you can not use their power rate as a guide. I would guess the bulbs you are taking out are 60W equivalent.Compare them to the incandescent equivalent or the luminous output. Would you want five 100W incandescent light bulbs in your fixture?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 22, 2022, 02:58:30 pm
content: Just a comment about the 9W led lamp which has 800 lumens.I suggest the next time you buy a LED light, just never ever buy one that is below 100 lumen per watt. LED's can have an efficiency upto about 120Lumen per watt, but unfortunately it is not so simple. The "blueish" LED's have the highest Lumens/Watt, and that is why the "High CRI" (Color Rendering Index) LED's tend to have a lower efficiency. It gets even more complicated if you factor in the human eye, which is most sensitive for green light, so you need less lumens to get the same "viewing ability".I also guess you usually can't save much by buying cheap LED lamps for two reasons. First, they tend to overdrive the LED's, which lowers their efficiency and raises their temperature and this leads to premature failure. Secondly, they tend to save each cent possible out of the thing, which lead to low quality electronics which also leads to premature failure.

author: james_s
author_rank: Super Contributor
timestamp: July 22, 2022, 05:06:03 pm
content: Quote from: BrokenYugo on July 22, 2022, 03:58:12 amThose only appeared because initially electricity was only used for lighting, houses had light sockets, so then some appliances got developed that connect to those. While code does not prevent it, there has also never been a requirement to have separate lighting circuits, lights traditionally are just fed by whatever circuit(s) feeds the rest of the room.

author: IanB
author_rank: Super Contributor
timestamp: July 22, 2022, 05:15:22 pm
content: Quote from: janoc on July 21, 2022, 05:44:50 pmNo, this is (was) an absolutely real problem. Either solid core or flexible wire goes to the light fixture, where the wire is attached to the bulb socket. The bulb gets hot, the fixture gets hot, the wire gets hot, the insulation degrades. I have looked at many light fixtures where the insulation has dried up and crumbled close to the socket, especially if vertically mounted with the bulb downwards.

author: IanB
author_rank: Super Contributor
timestamp: July 22, 2022, 05:20:49 pm
content: QuoteQuote from: eeguy on July 21, 2022, 07:32:07 pmQuoteQuote from: eeguy on July 21, 2022, 10:19:42 pmIt's generally not a good idea to use blubs where bulbs are indicated

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 22, 2022, 05:34:26 pm
content: Quote from: IanB on July 22, 2022, 05:20:49 pmKeen eye

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 22, 2022, 05:45:39 pm
content: Quote from: IanB on July 22, 2022, 05:15:22 pmI guess the confusion here is in the current supported by the wiring and the heat it can take before drying up and crumble.1.5mm2 or 2.5mm2 can transport a lot of current without a problem, but when the appliance connected to it generates a lot of heat it might cause problems and start a fire either due to the heat or sparking through the degraded insulation.A wall socket or outlet also has a limit due to this. For instance a big space heater can heat up the socket or outlet due to the contact resistance. This heat can also spread into the wiring. House fires can easily start due to these kind of things.

author: james_s
author_rank: Super Contributor
timestamp: July 22, 2022, 06:39:42 pm
content: Quote from: pcprogrammer on July 22, 2022, 05:45:39 pmForget the current, it's nothing to do with the current, the issue is the heat that comes from the bulb. Remember those Easy Bake ovens for children? They were common here in the USA at least, they used a 100W incandescent bulb as a heat source to bake cookies and such. Around 95% of the energy that goes into an incandescent lamp is turned directly into heat, and a portion of the light emitted gets trapped in the fixture and also turns into heat. Incandescent light fixtures can get very, very hot, I remember burning my fingers on those swing arm desk lamps that were once so common. Take a fixture that already gets scorching hot with the correct bulb and then install one or more that are higher wattage than the fixture is designed for and that's when you get crumbling insulation, melted junction boxes and fires from overheated combustible building materials.