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Standard 150W (equiv) Bulb in a 50/100/150 3-Way Lamp


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I've got another bulb-related electrical question for anyone that can help:


If I install a standard (non 3-way) 150W (or equiv LED) bulb in a 50/100/150 3-way lamp socket, can I expect to get the full brightness from the bulb that I would get as installed in a standard 150W Max receptacle?


I've got a basic understanding of how 3-way switches & bulbs work. I know there are two conductors, one for the 50W "filament", and one for the 100W "filament", and the last setting of the switch uses both filaments (or circuits in an LED?).


What I don't understand is if the lamp socket is what is limiting the wattage to each conductor, or if it's strictly the bulb and filament or LED circuit that limits the output (lumens)... Does a standard (non 3-way) bulb make contact with only one of the 3-way contacts, or does it use both of them and the additive effect can supply the single-filament bulb with the full 150W to reach it's full brightness. If only one of the contacts is used with a standard bulb, is it limited to the 50W or 100W? Or does it still draw the needed 150W (or LED equiv) from either contact?


Also, in searching the rest of the web, I've found that it should be perfectly safe to do this (regardless of how well it works), but some confirmation on that would be great, too.


Why I'm asking:


I've currently got two wall-mounted 3-way lamps in our living room, each with a Feit Electric 3-way 150W LED bulb. And I've recently added a Smartthings hub and Amazon Echo to our network and begun expanding our home automation beyond the couple of WeMo light switches we already had. I found a Leviton Z-Wave plug-in lamp-dimmer module that I want to dim the two wall lamps with (they are wall mounted, but they are lamps with standard 2-prong electrical cords).


I double checked the Amazon page for the 3-way Feit Electric bulbs that I have and it said they are dimmable, but upon testing, they don't seem to actually be. I'm guessing they meant that they can be dimmed via a 3-way switch... So I found a similar bulb that is just a standard 1-way 150W equivalent bulb, also from Feit, that specifies it is fully dimmable. I want to get these fully dimmable bulbs, leave the 3-way lamp switched on, and control the on/off/dimming of the lamp-dimmer remotely. But I don't want to lose the maximum brightness of 2200 lumens because of the 3-way lamp socket.


Does anyone know absolutely for sure if this is doable while retaining the full 2200 lumens available from the bulb at 100% brightness?

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You have a lot of questions so let me know if I miss anything.


1. incandescent 3-way bulbs (50-100-150 or similar) change brightness by first powering one filament (50W) or the other filament (100W) or both filaments (50W + 100W = 150W).  There is nothing special about the 3 way socket other than it has essentially two circuits that are either A or B or A+B or None.


2. A 3-way LED bulb is going to work the same way except there are two LED circuits in the bullb.  First one is powered then the other then both.  Again, there is nothing special in the socket except the two circuits.


3. A standard bulb in a 3-way socket only contacts one of the circuits.  You can try this by installing one and then turning to the first position (filament illuminates), 2nd position (bulb goes out), 3rd position (bulb illuminates), 4th position (bulb is out).  It may also be OFF, ON, ON, OFF.  I can't remember for sure.  It wouldn't matter if both circuits were on at the same time since it is the same supply source.


4. Nothing in the 3-way socket limits the power (wattage).  In fact, you could remove the 3-way socket and replace it with a non-switched or std switched socket and it will still illuminate a std bulb or std LED at full brightness (assuming there is no dimmer in the circuit).


5. DIMMING LED bulbs - guess what...you have to have a dimmer that is compatible with LED bulbs in order to dim them.  I don't know if the Leviton lamp dimmer module you are describing is compatible with dimming LEDS.  You need to find out.  One thing I have learned in my own house is that a standard dimmer will work (sorta).  I have recessed lighting that I switched to LED flood lights.  My standard dimmer works but it can't dim the LEDS as low as the dimmer I use on another set of recessed LEDs.  The dimming is also not linear because LEDs don't follow the same dimming power curve as an incandescent.


So the ultimate answer to your question is the 3-way socket will have no impact on the brightness of the LED but the dimmer you use actually might.

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Thank you, cskenney!


That was a fantastic, informative answer.


And yes, I do know that the dimmer should ideally be designed for LEDs. I am pretty positive that the lamp-dimming module is. I've already had some experience with LED and non-LED dimmers. Our dining room lights are 5 LED bulbs in a small chandelier, controlled by a standard dimmer, not specifically designed for LEDs. My first try with a bunch of old Cree bulbs produced a loud buzzing sound, but dimmed well enough. I returned those and bought some slightly more expensive Philips bulbs and the buzzing nearly disappeared. The chandelier dims fairly well, but yeah, it can't go as low as incandescents would... I just recently installed some WarmGlow Philips bulbs in our rec room canister lights and a Leviton Z-Wave LED dimmer, and they dim almost as well (and as warmly) as incandescents would.


I think I'm going to pull the trigger and buy one of those dimmable 2200 lumen bulbs and a wall-mount dimmer switch. Thanks again for the info!

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