Submitted by notscammed t3_101by7e in DIY

I want to put 6 sunco 5000k LED downlights in a room and run them all off a single dimmer switch. The lights say "14W Equivalent to 100W" and the switch says "LED 150W" and "Incandescent / Halogen 600W".

My first thought was that my LED load would be 6 lights at 14W each = 84W and the switch can handle 150W so I can put 6 lights on the switch.

But when I look it up I see some instructions saying the switch rating needs to be divided by 10 and some don't mention that, neither give any explanation as to why.

Neither the instructions for the LEDs nor the switch seem to address this clearly.

I'm completely confused. What switch ratings need to be divided by 10 and why?



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1feralengineer t1_j2mkahc wrote

Your dimmer is fine.

The division has already been done for you.


Ok_Television_9348 t1_j2mvkuw wrote

I agree. You only need to divide if the dimmer didn’t explicitly say for LED. Divide by 10 is a quick and dirty conservative way of converting incandescent rating to LED rating.


cannondave t1_j2n02io wrote

If the dimmer has a range of 5w to 100w, can I only dim the load down to 5w, for example a 10w light down to 50% (which is 5w)?


Redthemagnificent t1_j2n2uhn wrote

Dimmers don't work by limiting the number of watts. They work by reducing the AC voltage going to the lights. That's how you can dim a 100W incandescent and a 10W LED with the same dimmer switch.

That's also why some LEDs are not dimmable. They need the circuitry required to convert lower "dimmed" AC voltage to the right DC voltage so the light dimms as expected.


jzooor t1_j2n56uu wrote

Dimmers work by "chopping" out the lower voltage parts of the AC waveform. Every time there's a zero voltage crossing the circuit turns off until the voltage has increased enough again to turn back on at whatever set point the dimmer is set. The average (RMS) voltage is reduced because the circuit is off for some short period, but the peak voltage stays the same.


HanzG t1_j2n8w03 wrote

Worth noting that old style dimmers with turn knobs and slider-paddle type are a variable resistor and induce a voltage drop. These are still for sale in stores today and some LED bulbs will work with them, but some will not.


Riegel_Haribo t1_j2nieqv wrote

No they aren't, not any that go in a normal outlet box. Older dimmers are also a SCR chopper, but they work on leading edge of the phase which doesn't work well with LED. They also may need more minimum current draw or lower impedance than an LED fixture takes in order to operate correctly. They latch "on" starting at a particular voltage to the end of phase zero crossing.

LED+ dimmers (aka HED technology, C-L technology) have more circuitry ensuring that even slight loads will still get proper regulation. They can be reverse phase, that starts "on" and turn off at the correct duty cycle point.

Early rotary rheostats or variacs capable of controlling lighting were huge.


velifer t1_j2nx0n4 wrote

>No they aren't

How strange that some I've removed from my older house were rheostats, exactly as described. Maybe you could consider there are houses built before 2010.

You're ill-informed.

rotary rheostats were extremely common and fit into standard work boxes.


asr t1_j2pfg4c wrote

Sorry, but it's you that is wrong. No one uses rheostat dimmers, they would radiate a ridiculous amount of heat - basically the entire heat load of a lamp, inside a tiny box.

/u/Riegel_Haribo is correct.

Maybe you are confused because they look like rheostats, but they are not.


velifer t1_j2psnxx wrote

If you don't think the multi-wound rheostat dimmer for home lighting and fans was ever a thing, then I'm sorry that facts are hard for you. Yes they sucked. Yes, they could get hot. Yes, they absolutely were used in houses and in a form factor that fit into standard work boxes.


asr t1_j2q5rr4 wrote

No they were not. Sorry, but rheostat dimmers simply get too hot to be placed inside electrical boxes on the wall.

You are just mistaken about this. They can only be used in specialized applications with the load exactly matched to the rheostat.

They were never used for general purpose lighting in homes.

I don't even get how you think they were supposed to work - the rheostat has to match the load exactly, how exactly would you even install them in a home where the homeowner can change the light bulb?

(Fans are a different story.)


EliminateTimeZones t1_j2qafne wrote

Variable autotransformers do not need such close load matching and definitely have been used in residential applications. Bigger than your standard wall switch, but sold in a form factor to be installed in a standard 2x4 studwall


TrainerNaive t1_j2r5rl7 wrote

Your house would soon be on fire if you fitted a simple rheostat in a regular wall box and used it to control more than a few watts.

The other folks are right, the earliest domestic lighting dimmers (late 60s onward) used semiconductor switches. Commercial premises, school halls and theatres had rheostat dimmers before that but they were in huge cabinets and dissipated huge amounts of heat.

Very low power fans might have been controlled by rheostat. More likely rotary variacs (variable auto transformers).

I am a chartered electrical and electronics engineer with over 50 years' experience.


sudo_mksandwhich t1_j2q5r9b wrote

But did you actually take one apart and confirm that there is not an SCR inside?


EliminateTimeZones t1_j2qaz0q wrote

The ones installed in a standard workbox are not purely a rheostat/resistor/autotransformer. Older dimmers that don't involve a chopper circuit are much bigger, but certainly do exist. It's possible that a 100-150W unit could be fit into 2 gang box, but I've never personally seen one.


Riegel_Haribo t1_j2o3132 wrote

Maybe YOU should consider solid-state SCR dimmers were in use since 1961:

edit: amazing how many button-pushers don't realize the the nonsense they are upvoting above. Dimming lighting with a variable resistor in a utility box would be a ridiculous hazard. At particular setting you can have made a voltage divider with as much power dissipation in the box as from the total of incandescent light fixtures.


purrcthrowa t1_j2ob6o3 wrote

Exactly. I remember my dad installing a solid state dimmer in the extension to our house in about 1973, and they were common then. The only problem was that he found it quite difficult to source as he needed a pretty high power one (750W or 1kW - something like that). We also had a couple of wire-wound linear rheostats which were probably about 1kW capacity each, and which my dad used for amateur theatre lighting and these things were huge - about a foot long and about 4" square in section. They also needed a lot of ventilation to keep cool.


asr t1_j2q6evz wrote

Thank you. /u/velifer is simply wrong about this. Your memory of wire wound rheostats matches what I know - they are huge, used for theater lighting, and need cooling.

They were never installed in general purpose home lighting.


[deleted] t1_j2or2bk wrote



asr t1_j2pfkb0 wrote

Except that he's right, and you are wrong. And your childish insults doesn't help your case at all.


velifer t1_j2q2z45 wrote

Interesting. There's an old one for sale.

One of those things you say doesn't exist.


Here's the thing: your tone policing doesn't make you correct.


asr t1_j2q65y8 wrote

That is not a rheostat for lighting, it's most likely removed from the speed control of a motor.


EliminateTimeZones t1_j2q9v50 wrote

That is a dimmer. It says right on the cover dimmer. It's a variable autotransformer in a box,.which will dim incandescent bulbs just fine. But maybe only a hundred or so watts looking at it's size.

I have in my possession several Luxtrol WBD series lighting dimmers with a similar electrical configuration that were removed during a dining room remodel.


Doctor-Funkenstein t1_j2psms4 wrote

Lol I'm glad this is the rabbit hole I went down tonight. The true electrical nerds know whatsup while the hive-mind goes towards what seems like an obvious answer. I feel like this dimmer switch thing is a metaphor for so many other things. Voltage phase control is most definitely NOT a new technology. Those light switches would put out a tremendous amount of heat with even a couple amps, and incandescents are Amp suckers.

A dimmer looks like a pot, but it's not!!!


EliminateTimeZones t1_j2q66xf wrote

I have some actual rheostat dimmers I removed from an old dining room. They weigh about 10lbs each and are in cast iron boxes that are about 5x4x3 inches in size.


asr t1_j2pfp3j wrote

That is not worth noting because that's not true.

Older dimmers are NOT variable resistors! That's simply not true.


HanzG t1_j2pnupv wrote

"Modern dimmers are built from semiconductors instead of variable resistors, because they have higher efficiency. A variable resistor would dissipate power as heat and acts as a voltage divider. "

Is this quote not true? Were old ones were not resistor types that induce voltage drops?


EliminateTimeZones t1_j2q94xj wrote

I have some Luxtrol WBD series variable autotransformers that were removed from residential dining room applications. They are much bigger than your standard wall switch, but designed to fit into a wall cavity.


asr t1_j2q53km wrote

Correct, the old resistors based ones were not used in homes, only in commercial applications (theaters).

They were too large and got too hot to be useful in homes.


EliminateTimeZones t1_j2q6h6n wrote

I've seen them in homes, typically dining room chandeliers. They are big and got hot, just like you state.


asr t1_j2q6qxc wrote

Those are not rheostat (resistor) based though. They use thyristors to chop the electrical current (you can hear them humming if you listen closely).

Basically they are switches that turn on and off very quickly.


EliminateTimeZones t1_j2q8tba wrote

Nope. Definitely a thing. Also I'm corroborating your claims that they are too big to fit in a standard electrical box.

I just pulled mine out of basement storage and took a look. Inside is a variable auto transformer. Lookup "Luxtrol WBD" on eBay to get an idea.


EliminateTimeZones t1_j2qb548 wrote

Nope no thyristors in these. Just checked. Just a variable autotransformer. (Not a resistor or rheostat).


Fine-Team-4296 t1_j2sr1fj wrote

There are 4 general types:

The only ime I've seen a variable resistor in real life is in a car. It was for the high medium and low select on a fan speed for heater and a/c. I doubt they would have used them in a house because it would be dangerous due to the heat it creates but who knows.


fomoco94 t1_j2oel6m wrote

That's not true. The peak voltage also will vary for the typical phase shift dimmer. It's just not a linear function of the RMS voltage.


asr t1_j2pf145 wrote

TRIAC based dimmers do that. But newer (and better) MOSFET types cut out the high parts of the waveform instead.

They work better for LED's - more compatibility, and the ability to dim to lower levels.


cannondave t1_j2wf5yu wrote

Very interesting. So if a dimmer supports minimum 3w, I can put a 3w dimmable led light, and dim it all the way down from 100% to 0% (give or take)?


ShuRugal t1_j2o4b9l wrote

>Dimmers don't work by limiting the number of watts

Unless it's a constant power dimmer.


jrabel1 t1_j2rcwdh wrote

Yes, like the first Ford's, "you can dim to any level as long as it's 67%..."


InvincibleJellyfish t1_j2o3byl wrote

It could also lead to flickering in LEDs even if they are "dimmable" as the dimmer just chops up the AC waveform. At least some of them do. This leads to a lot of spikes which can lead to both flicker and an annoying buzzing sound.

Those wifi or bluetooth controllable LED bulbs are much nicer, although way too expensive imo.


created4this t1_j2o9h5c wrote

It’s worse than that, a standard (cheap) dc supply as used in a LED lamp uses a capacitor to limit the current as the capacitor charges and discharges on the AC cycle it lets a small amount of current flow, but if the AC signal is not smooth then the capacitor and the rest of the circuit get the electronic equivalent of jerk on every cycle, which stresses everything and will rapidly lead to failure.


Raul_McCai t1_j2nx74n wrote

> Dimmers don't work by limiting the number of watts. They work by reducing the AC voltage going to the lights.

That might be an old rheostat dimmer. Modern ones turn the power on and off at a rate so fast you don't see it to produce the dimming effect.


StoneTemplePilates t1_j2pnhq5 wrote

What is the division necessary for? If the dimmer is good for 600W then why can't it handle ~40 x 14W?


1feralengineer t1_j2qbvvq wrote

The 600w rating is for a pure resistive load.

LEDs are a nonlinear load. They would fall in the capacitive category (the current leads the voltage by about a factor of about 0.8 full load/brightness). Dimming them can shift the power factor significantly (just because the wattage is reduced doesn't mean the current is reduced - especially peak currents that interplay with the semiconductors that do the heavy lifting of the dimmer).


StoneTemplePilates t1_j2rhr67 wrote

>just because the wattage is reduced doesn't mean the current is reduced

How come? The LEDs still run on 120volts so if the wattage is reduced and the voltage is the same, then the current has to be lower. What am I missing?


1feralengineer t1_j2rnsfk wrote

>What am I missing?

Power factor.

VA only equals watts in a purely resistive circuit (PF=1). In an AC circuit if the current sine wave leads the voltage sine wave (capacitive load), or the current sine wave follows the voltage sine wave (inductive load) the apparent power (VA) is higher than the actual power (W). PF=W/VA


StoneTemplePilates t1_j2s3det wrote

I'm gonna need to do some googlage to understand this, but thanks for the explanation!


According_Instance42 t1_j2tr932 wrote

The dimmer rating for 5 -100w means that if the load is lower than 5 watts, the dimmer cannot work, because it cannot detect the low watts. If the watt is too high, it can blow up the fuse in the dimmer, so it doesnt work either.


_ALLien_ t1_j2muik6 wrote

5000k is sharp cool white. If this is for a residential application you should consider something closer to 3000k. If this is a workshop or similar 5000k makes better sense. That’s my .02.

The load is fine. You were correct in adding up the points. If you have trouble with dimming (flickering, etc) you might need an LED compatible dimmer.


BigSmokeyTheBear t1_j2n3h1k wrote

100% this. People are turning their homes into offices and it’s driving me absolutely mad. Go into a house with white light and I literally can’t relax. Turns everything from a warm inviting home to a cold prison cell. Just my perception- but I recommend you not decide between one or the other and get something high lumen and temperature adjustable, install it, then adjust it to your preference. Some people confuse lumen output with color temperature- and hence cold residential prisons. If you can’t see get something 3000 lumen instead of 600 and I promise you’ll see everything regardless of color temperature.


nycola t1_j2n5kp7 wrote

I'm cracking up, my younger cousin got married recently and has entered the world of home ownership with her husband. At Christmas she was telling the story of how she asked him to go to Home Depot to get white lights for their tree.

So he went to Home Depot and got white lights, but they were the blue-white ones instead of the traditional warm-white ones. She grew up with a Martha-Stewart-Like mother (My aunt is the living embodiment of pinterest). She told him to take them back and get the proper ones, he could not, for the life of him, figure out how he got the "wrong" white lights.

So she ended up going back to Home Depot to return them, but she kept one package, then got the "right" white lights.

So she takes them home to show him the difference and he says "I actually like the white-light ones better" at which point she tried explaining color mood to him and he started watching football.


fuelbombx2 t1_j2nbk80 wrote

Well, either this is the first crack in their marriage or they’ll be laughing about it at their 30th wedding anniversary. Hopefully, it’ll be the second one.


jasonmp85 t1_j2o6e9c wrote

Why, he sounds like a dolt and she sounds incapable of communicating specificity, let it fail.


sudifirjfhfjvicodke t1_j2n5z0x wrote

I use color tunable smart bulbs in a few areas of my house that offer a "circadian rhythm" setting that automatically adjusts the color temperature throughout the day. Starts off in the morning around 5000k and gradually adjusts to around 2800k by the evening. I love it this way, I need that white light in the morning to help me feel more energized, especially since our living room doesn't get a lot of natural light.


Jewrisprudent t1_j2nefnh wrote

This is the only way. I’ve had a combo of Hue and LIFX lights throughout my house for the last 4 years, it absolutely drives me insane when a room is not properly lit now.

It’s 2023 people, we have the technology to perfect our room’s color temperature!


Deadofnight109 t1_j2nnpeg wrote

100%, I spent the extra for the color hues mostly for all the color temperature settings. The main lights rarely use the full color settings. But it sure is nice when I need some extra visibility that I can change everything to a nice crisp cool white.


ZeroMayCry7 t1_j2o0t89 wrote

Yup. My friends new house has new recessed lights that are a bright white and it does not feel homey at all


SyncRoSwim t1_j2nlb8d wrote

After renovating our kitchen with a lot of deep blue elements, we experimented with lighting in various temperatures. The 5k lights looked the best, hands down.

Normally, I’d agree with you - we use warm whites in the 2.3 to 3k range everywhere else in the house. But there is a place for 5k!

Since we had to order the lighting before the renovation was done, all I can say is thank goodness for fixtures with variable temperature settings. Because of my bias towards warm light, I’m certain I never would have chosen 5k in advance.


coyote_of_the_month t1_j2o07jh wrote

When we bought our house last year, it was yellow-biege, including ceilings, and was mostly lit with honest to God incandescent bulbs.

We painted it a cool off-white and went overboard with 5000K daylight bulbs, if I'm being honest. It made such a difference! Our close friends haven't been shy about saying they hate it though, and I'm coming around to maybe buying some 3000K bulbs as the memories of the beige start to fade.


sunflowercompass t1_j2n6i29 wrote

3k is too orange, it is the color of light during sunset

I need 4k to stay awake and keep seasonal affective disorder away. 4k is the color of the sun at noon. 4k is the closest to "neutral white"

edit: oh one more variable. The furniture and wall colors you have will affect how light looks. If your walls are yellow like mine the light will look yellower.


Mr-Thumpasaurus t1_j2nfk2e wrote

Have you considered smart bulbs? I have mine transition throughout the day. That way you have the best of both worlds

An alternative for more analog systems would be to get some lights like the Philips "Warm Glow" bulbs, which transition in temperature as you dim them


sunflowercompass t1_j2njm6f wrote

I have some phillip smart bulbs. A bit expensive thought and not bright enough for my living room. I replaced them with 3 big LED fixtures at 4k with a dimmer switch. In the evening I use it at the bare minimum, color temp doesn't really matter at that point.

For the bedroom the old warm temps are fine, you want warm lights to go to sleep anyway.

edit: oh I remember why I disliked the phillip lights. They are a neat party trick but I hated the app to control them. If I did it again I'd make sure there's a hardwired control at the switch. Yes it means you need to get up.


lostarchitect t1_j2nm5g5 wrote

The GE Cync smart bulbs are surprisingly affordable. I put a bunch of them in my basement where I had a bunch of individual ceiling lights with pull chains. Now they all go on at once with the press of one smart switch. I'm also using them around the house in places where I can't have a dimmer but would like one.


FerretChrist t1_j2o25qa wrote

I have Philips Hue bulbs throughout the house. The app is pretty decent when you want to dive in and edit colours and scenes, but I couldn't live using it day to day just to turn on and off the lights, that would be insanity.

I've attached "Hue Wireless Dimmer" controls next to every light switch. They turn the lights on and off, cycle through different scenes, or turn up/down the brightness. Best of all, they attach magnetically, so you can pull them off the wall and control the lights while you're sat down.

The only downside (except the price!) is they're battery powered, but I've had them in for two years now and not needed to change a battery yet.


RickFast t1_j2ng5nh wrote

Daylight is 5600k.

It totally depends on the usage of your lights.

Using during the daytime? Anything 4000 and up is appropriate (that’s why it’s used in offices, warehouses, etc)

Using them at night? Anything above about 3500 is gonna look nasty and leave a bad strain on your eyes.

In a perfect world use smart ones that can change the colour temp


ahecht t1_j2ok45a wrote

> 4k is the color of the sun at noon.

Depending on the season and your latitude, noontime sun is somewhere in the 5000-5800K range. 4000K is closer to early-morning or late-afternoon sunlight.


Mrgoodtrips64 t1_j2nh457 wrote

The color of the sun at noon isn’t consistent. It varies slightly by time of year and the viewer’s geographical location.


Paldasan t1_j2ncayo wrote

Pitching in to recommend that any subsequent readers who wear makeup to consider matching their bathroom lights to their place of work lights for colour temperature. That way when you apply your makeup it will closely resemble how it will look at work, or substitute for wherever else you might feel most comfortable projecting your modified appearance.
For those who don't use makeup, then I would suggest a cooler white, it might help you keep track of your skin and observe any changes that might be occurring (such as the size and shape of any moles, which could indicate skin cancer).


HanzG t1_j2n9ixf wrote

Agreed! 5k is too cold for us too. I bought a handful of 4500 or 5k bulbs from the local Orange store and put them in the outdoor fixtures of my rural home.

Terrible. Cold, stark white like an operating room in the middle of farm land. Swapped them out for 2700k and lower "wattage" and they're much better. I tried the bulbs in the fixtures in the house but again the only place it was decent is the basement workspaces.


LateralThinkerer t1_j2nu5u0 wrote

3000K - 4000K FTW depending on where you're using it. Work areas you might actually like the "harder" 4000K or more but for interior domestic areas the lower color temperature is best. Also don't be afraid to actually check out lit bulbs in a big-box store if you can...manufacturers will fudge their color temperatures sometimes though this becoming is less common. Source: Light nerd who's refitting his house away from fluorescents.

Here's a graphic guide


maddips t1_j2odrc2 wrote

Different folks right? I assumed this was for a grow room to need that mich lighting on 1 switch


jzooor t1_j2n5ugn wrote

Only 2700K bulbs in our house. We have a few task lamps with higher K in them for desk work and other focus tasks but everything else is warm white.


colinstalter t1_j2ngqdi wrote

Yeah the other comment about 3000k being super orange is nuts. Our whole house is 2700k and they perfectly match the OG light bulbs that I haven’t changed yet.


ayyylmaowut t1_j2mx1lf wrote

I hate anything below 4000k. Yellow lighting is atrocious imo, and I can never see as well vs whiter lighting….but yellow does match better with traditional aesthetics. For a modern style and cooler colors in a home, 4000k - 5000k works great. It’s not only for shop lights. Lol


nye1387 t1_j2mzjtu wrote

I'm curious: what part of the world are you in? Turns out there are some strong geographic preferences that are often (not always) linked to local climate. People in deserts tend to prefer high-K lights, and people at high latitude tend to prefer low-K lights—both the opposite of what they tend to see outside.


ayyylmaowut t1_j2n1wld wrote

I’m in subtropical, so warm and wet. My parents have mostly yellow lighting most of my life. I didn’t really have a strong opinion until I bought a home and had painted 3 walls before I stepped back and realized I hated how the paint looked on the walls. The minute I changed out the light bulbs from the 3000k to 5000k, suddenly the light gray/white paint looked more gray/white and less magenta (apparently had 1/64th magenta in the formula and I could see it with the warmer lighting).

I prefer higher K due to the very real effect it has on cooler colors and style of my home. Also much easier for me to actually see.


Redthemagnificent t1_j2n3g4d wrote

This makes a lot of sense combined with the previous comment about location. I grew up in cold, high latitude location and I love 3000k lights. 5000-6000k just reminds me of bright sunlight reflecting off the snow and the florescent lights used in schools. 3000k reminds me of sitting by a warm fire. Cozy


nye1387 t1_j2n7acr wrote

This is exactly what I meant above. Nice to have anecdotal confirmation!


sunflowercompass t1_j2n6qu0 wrote

I think it's how you grew up maybe. I grew up closer to the tropics so I prefer bright, intense lights. High K lights like the ones from CFL depress the fuck out of me.


dilligaf4lyfe t1_j2nbsu3 wrote

Warmer lighting is fine for most tasks, if you're having issues with task visibility you probably just need more lights. Most people I see with this issue are relying on a few ceiling lights to do all of the lighting work - minimal ceiling lighting will generally be there to provide ambient light, and should be supplemented with additional lighting for tasks. Lamps in locations where you're reading or writing, pendants or cans in kitchen areas over countertops etc.

I run into this pretty frequently, a customer will have one boob light on the ceiling cranked to 5000k so they can do tasks in the area, when layered, task specific lighting to supplement would make the space a lot more functional without a glaring, cool ceiling light completely dominating the space.

It's all personal preference of course, but I think most people associate overly cool light with hospitals and offices. Really my biggest pet peeve is people who have an assortment of different colors like they just randomly bought whatever bulb was in front of them (which is frequently the case). I can't stand multiple can lights that all have a different color. You can layer in different color lights if it's done with some intention, but man I usually think it looks horrible.


ayyylmaowut t1_j2nhlur wrote

Lmao I also can’t stand multiple colored lights in a shared space if they’re for the same purpose. We have accent lighting that can be 4000k but all our general ceiling+ lamp lighting is 5000k. We also have task lighting that supplements the general purpose ceiling lights (under cabinet light bars), but we also prefer those set to 5000k, although I have turned them down to 3000k - 4000k before, like when it’s late and I don’t want everything on or we’re watching a movie and want minima background lighting.


ButtRash69 t1_j2mybs2 wrote

Agreed, I’ve slowly been swapping every light bulb/LED panel with bright 4000k dimmable light bulbs

Yellow lighting makes me want to puke, our carpet is grey so it makes it look like it has pee stains with tired eyes and our walls are blue so it gives them a green tint


_ALLien_ t1_j2mynhl wrote

Warm light also matches natural lighting more closely - at the hours you’re typically relying on interior light. High noon is closer to 4000k light. Sunset, sunrise, and low angle sunlight is warmer - which is when you’re typically relying on interior lighting. Warm light is for cozy, relax hours. Cool color light is for mid-day active hours. Most smartphones have the option to auto-shift the screen color temp similarly. Places of work and shopping centers typically have cool white light to promote alertness. Restaurants and spas use warm light to promote relaxation.

But do what you like!


LavenderGumes t1_j2na7sm wrote

Hey OP, I'm assuming based on the 600W/150W breakdown, this is a Lutron dimmer, because that's their standard incandescent and LED load limits for most of their LED+ dimmer line. If that's the case, I want to add a tip for you:

Depending on the LED, it's likely the lamps will strobe, shimmer, or simply turn off when you dim down to the low end. This is common with LEDs. If this happens, Lutron has a feature called low-end trim which adjusts how low the lights will dim. This allows you to avoid dimming so low the lights start to have issues. Just look for it on your instruction sheet.


5degreenegativerake t1_j2nljus wrote

Legrand also has a “Calibration” adjustment on their dimmers for the same reason.


Tack122 t1_j2o0yr2 wrote

I use that with my dimmers, but what I'd also like is to regrade the scale.

I use the app on my phone and have my lights set to minimum 20% on the low end trim thing, but I only really get dimming between say 50% and 20%, and the low 20%s are nice for night time, low light.

But it's fiddly when the bar has 20-100% on it, and you're only trying to use a tiny section of it.

I wish I could increase the size of each setting from 20-30 relative to the size of 70%-100%. 70% to 100% looks about the same without a light meter so the difference is relatively unimportant.


LavenderGumes t1_j2ol5hh wrote

That's called dead travel in the lighting world. It's a common LED issue.


ZeroVoltLoop t1_j2nlm29 wrote

I use this feature. I generally adjust trim so that the lights come on when I dim up from off. When I do that, it usually is bright enough to not strobe when you dim all the way down from fully lit.


[deleted] t1_j2oa9gl wrote



Firehed t1_j2ojs89 wrote

All the dimmable LEDs I have work fine without any flickering at the default lowest brightness setting on Lutron Caseta dimmers. I’ve got a couple of HD store-brand ceiling lights that turn on in a weird way (I assume a capacitor is charging or something) but after a few seconds they’re fine too.


LavenderGumes t1_j2okyb3 wrote

If you're buying big name brand LEDs, you're likely getting good performance. I think the Caseta dimmers are already set for a low end trim out of box to account for typical performance issues. You may want to check your app to see if you can reduce to the trim if your LEDs are performing well and you want more range on the low end.


Firehed t1_j2ol60n wrote

Oh, good to know! Wouldn’t mind having a couple rooms dim even lower at times.


anonymous_lighting t1_j2opq9n wrote

you have an 84W load as you noted. you’re fine

5000k. are you performing surgery in your house?


StoneTemplePilates t1_j2pogi7 wrote

Lol. When moved in, my kitchen had TWELVE 5000K 48" Fluorescents. It's not a large kitchen either, maybe 10' x 14'. I immediately removed all but two and it was still ridiculous until installed 3200k down cans shortly after. I think some people don't want to admit that their eye sight is degrading so they just put more lights in.


signal15 t1_j2q4zll wrote

Yeah, no shit. 5000K in a living space... Makes me want to leave immediately. It's fine in a garage, utility room, or workspace. I keep all of my living space lights between 3000-3200k.

My friend just put in a bunch of 5000k leds, and then took them out the next day because they made him feel sick.


predditr t1_j2rrwkf wrote

5000k is what my wife prefers. Sigh. We just added LED ceiling lights in the future baby room, and I pretended they didn't have a 5000k color setting. Baby doesn't need to grow up like a lab rat.


anonymous_lighting t1_j2rwlsy wrote

as a lighting professional, i often find people mistake brighter white for more light which is untrue. maybe your wife thinks she likes 5000K based on the feeling it provides more light. maybe a mini lesson could help. lumens are the measurable output and the appropriate amount for the setting makes all the difference


NCaliZen t1_j2nscst wrote

The issue with LED fixtures is that they can have a significant amount of inrush - current that comes through the device when it is initially turned on. That inrush can destroy your control device.

(Note: This isn’t the first time something like this happened in the industry. When the industry moved from magnetic ballasts to electronic ballasts for fluorescent lamps, the new ballasts had a significantly higher inrush. A side effect was some manufacturer’s wall switch devices couldn’t handle the inrush and would be destroyed. The National Electrical Manufacturer’s Association (NEMA) worked on a standard to define an acceptable amount of inrush, but by the time the NEMA 410 inrush standard was developed, electronic ballast manufacturers had mostly redesigned their product to reduce inrush. History just repeated itself with the introduction of LED lighting.)

If you had a dimmer that didn’t call out a LED rating, the safest thing to do would be to divide it’s rating by 10, so a 600W dimmer shouldn’t control more than 60W of LEDs.

However, since the dimmer you have calls out a 150W LED rating, you should be fine loading it with - in your given example - 84W.


argon561 t1_j2nzb61 wrote

It's correct that the inrush current is the MAIN problem with LED lighting.. Though it should be noted that most dimmers now actually circumvents this problem by trickle charging the LED-driver capacitors, and by doing this, can absolutely handle the continuous wattage specification.

It's quite easy to check if you have such a dimmer (or LED-driver for that matter).

Turn the lights off. Let them stay off a couple of seconds.

Turn them on. If they don't respond IMMEDEATELY when the button on the dimmer is clicked (like they do when shut off), the dimmer is "trickle charging" the capacitors with it's own circuitry. When the inrush current goes below a threshold that is acceptable, the lights will turn on and "full power" is fed to the lights.

This can also be noticed if a LED "gradually gets bright", and not "direct full brightness" when it's switched on.

If it's a very old control device / dimmer, it might not have this feature, and on those, you'd be best of by dividing it's rating by at least 10.


HighOnGoofballs t1_j2ml5j9 wrote

You had it right, just add them up. You can use 10 14W lights. The divide by ten may have meant to get what size light if you wanted ten of them or something like that


aeric67 t1_j2o8iw3 wrote

I would really recommend you consider 3100K or less for indoors, unless you are setting up an exam room or something.


gregaustex t1_j2niz9n wrote

>My first thought was that my LED load would be 6 lights at 14W each = 84W and the switch can handle 150W so I can put 6 lights on the switch.

This is correct. These are 14W bulbs, they are just telling you what the wattage of incandescent bulbs with the same lumens would have been because for so long "watts" meant "lumens".

If you are using a normal variable resistor-based dimmer, you might experience some other weird things like not getting the range you want and some flickering. LEDs don't quite work like a filament in a vacuum. I've done it with dimmable LEDs and it works mostly OK but not perfectly.


theidleidol t1_j2nt61p wrote

I don’t think they’re confused by the “100W equivalent” part. They’re asking about the limits marked on the switch. The reason it lists both is that the dimmer is genuinely rated for a smaller LED load than it’s rated for an incandescent load. But then they also looked it up and found the rough formula for calculating that derating yourself (in the event it’s an older switch or whatever that hasn’t already done the LED math for you) and got confused.


Metsican t1_j2ncg3v wrote

Quick math says your fine. You should be able to get up to 10 on that circuit.


Silent-Catch-7323 t1_j2nd27g wrote

I prefer 5000 k but have good control of them . Also have more fixtures than most do. I only use light where needed and a lot of my 5k bulbs are extremely low wattage (25-40 watt equivalent) To each their own


tookmyname t1_j2nhc04 wrote

5000k is blue. 4000k I get, but holy shit 5000k is like those annoying people who have super blue headlights.


bcanddc t1_j2nem56 wrote

You’re good. I’ve put 8 of those lights on one of those dimmers.


knowitallz t1_j2nre6d wrote

You need to try this dimmer with those lights and see if it works. Many times the dimmer will make them flicker when they are dimmed. You may need a different dimmer.


Cloakmyquestions t1_j2ntkhn wrote

I heard that some dimmers might work less flakily with more lights on them (within reason). Thoughts?


StillWill18 t1_j2nub3f wrote

No idea. We have them on in fours. Was never a problem. I don’t see why 6 wouldn’t work, too.


TrogdorBurns t1_j2ph8zp wrote

The calculation is correct, but some led lights dim using pulse width modulation instead of the voltage regulation used in incandescent bulbs of the past.

Pulse width modulation works by taking an led that's "flashing" 60,000 a second and makes it half as bright by flashing on and off 60,000 a second resulting in it being on for 30,000 pulses and giving off half the light.

You need to know if the led lights are "dimmable" i.e. they have the dimmer in the bulb or if the led light is relying on the dimmer switch to provide the modulation for the bulbs.


RaederX t1_j2ppl5k wrote

The circuit is likely rated for 15 amps. The building code usually says not to use more than 80% of the available amps, so you have 22 usable amps. (Ontario building code, but representative of most North American building codes.

LED lights use a ridiculously low number of amps. I calculated at one point that each LED light in a set I was looking at used 66 miliamps (0.066 amps) ... which means 12amps divided by 0.066 amps per LED ... or 182 LED lights on a 12 amps circuit.


MaddVillain t1_j2q6myy wrote

This really has nothing to do with the question since the question is about the dimmer load, not the circuit load. You can only load the breaker to 80% as you said which is 12amps but the question is about a dimmer switch which can only be loaded to 150w or 1.25A at 120v. OP cannot put 182 LED lights on his dimmer switch.


Fine-Team-4296 t1_j2splrn wrote

I'm no electrician but that's not correct. First, what gauge wiring is ran to the lights. Second what average fuse is the line ran off of. Third, is there anything else sharing the lights with that fuse?

Those questions aside many companies recommend a max number of lights per switch. For example, verilight says 10 led lights max.

I mentioned some things you didn't ask about because I was unclear who ran the electrical. And your knowledge about what's on the fuse they may share.

"NEW" Dimmer switches CONTROL THE WAVE FORM, they have nothing to do with amps or voltage directly.

So even if you can control 10 lights on 1 dimmer - it doesn't mean you should. You need to do your research and answer the things I mentioned in the first paragraph.

This may determine while the dimmer switch can control 10 lights, but electrical line or fuse may only handle 3.


mint_me t1_j2mvny1 wrote

Load is always written on the side of dimmers, usually 1000 watts. Let’s say 1000 wats/14watt led equals 71 of those little fuckers


MeshColour t1_j2n40hi wrote

Dimmable LEDs tend to require fairly large capacitors for smoothing, so that can cause a quite large inrush current when they are switched on

I'm thinking that's the reason for the "divide by 10" idea (that is on the safe side compared to the labeled rating achieved by OPs dimmer)

In the case of a dimmer they are being switched on and off at 60Hz or more, the load on each cycle is very different than the resistive load of incandescent bulbs (unless mitigated by great circuit design)


mint_me t1_j2nzctc wrote

Yeah I was gonna edit my reply but meh I mean it would be interesting to see 71 leds on a single dimmer but really 20 would be a hard limit. Yes reactive loads etc etc


noeljb t1_j2nb177 wrote

My LEDs in my office ( 2x4 ft LED panels ) have a 10 volt dimming circuit. Dimmer has on/off switch and a slide dimmer. Lights have a pair 110v power wires and a pair of 10v dimmer wires. Darn thing was not cheap. Although the lights were quite reasonable.


ihatethetv t1_j2pig2v wrote

LEDs are difficult to dim and so you need special dinners and even those can’t dim too many watts of leds without having problems. LEDs cause noise and flicker a lot.

To keep it simple get a dimmer that’s led compatible and ensure the fixtures you’re using are explicitly listed as compatible. Otherwise you’re going to have a crapshoot.

Or do like I do and don’t use dimmers. They’re dumb.


Raul_McCai t1_j2nwygi wrote

I am assuming this is a 120 VAC line and the bulbs have a circuit in them that conditions the electricity to the LED's needs.

So - - Probably a hell of a lot of them. What's the Forward voltage of the LEDs?

The Kelven is irrelevant. In fact all those other numbers are irrelevant.
One thing I've learned dimming LEDS is that you need (at least you used to) a conventional load on a conventional dimmer. It can be a s little as a 15 Watt bulb but the dimmers need to see a regular load od they won't shut down and will flicker. I haven't had any experience with the newer dimmers that are made for just LED loads. Leutron makes some