3 way dimmer switch with high efficiiency when dimmed

Dave Angelini
Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
in Energy Use & Conservation #1
I am looking at dimmer applications and need one that can dim from both locations and do so with low loss when dimmed. I have looked at the Lutron MAW series but I am not sure how well they would save energy when dimmed. The last advice I received form Home Power magazine was to save your receipt. Not much help there... Thank-you!
"we go where power lines don't" Sierra Nevada mountain area
   htps://offgridsolar1.com/
E-mail offgridsolar@sti.net

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: 3 way dimmer switch with high efficiiency when dimmed

    The typical dimmer adjusts power flow by only turning on for part of the AC cycle...

    Filament lamps tend to become very inefficient as their filament temperature falls. But they also become "warmer" in color (very nice for a darkened room--feels like sunset/fire light).

    With CFL and LED fixtures (those that are designed for dimming), they do get "dimmer" but (for me) the dimmer white light is not very satisfying (feels "weak" or almost unhealthy/pale).

    If you have LED/CFLs that are not designed for dimming, the ballasts tend to still maintain normal light levels until there is not enough voltage. And the lamps may tend to flicker (unstable operation). With CFL's designed for dimmers--I still find that they tend to flicker on low and do not have that wide of range of dimming (from full bright to something that feels like 1/4 light--Not "dim" by what we are familiar with when using filament bulbs where you can get to a barely glowing bulb).

    So--My summary would be that using LED or CFL bulbs designed for dimming (and there are now mixed mode dimmers that are designed to work with both filament and LED/CFL dimmable lamps) do work and they should save energy.

    Although, dimmers may not "unload" the power source in terms of current (you may still have current spikes, but the "average current" is lower).

    But I would measure the power used (kill-a-watt, inverter monitoring) with the dimmer/lamp(s) in question. There seems to be many variables between mfg.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #3
    Re: 3 way dimmer switch with high efficiiency when dimmed

    I don't think they're different from regular dimmers. They simply use one of the wires to synchronize the microcontrollers in the dimmers. They will pass less energy to the load in dimmed condition compared to non-dimmed. There are also small losses inside the dimmer. Since you have two in series, these losses will be doubled.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: 3 way dimmer switch with high efficiiency when dimmed

    Not much loss in modern switching dimmers, quite unlike the rheostat types of the olden days. On the other hand, the old rheostat types didn't emit RFI, but could depending on the wattage they were handling, be used to supplement your winter heating requirements. Hahahaha
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #5
    Re: 3 way dimmer switch with high efficiiency when dimmed
    NorthGuy wrote: »
    I don't think they're different from regular dimmers. They simply use one of the wires to synchronize the microcontrollers in the dimmers. They will pass less energy to the load in dimmed condition compared to non-dimmed. There are also small losses inside the dimmer. Since you have two in series, these losses will be doubled.

    Yes I understand that there will be less energy to the load when dimmed but was looking for someone who had measured the circuit. This would tell me that when dimmed the rest of the two 3-way circuits were not wasting energy. I would like to think that when dimmed the total energy would be less and proportional to the amount of dimming. It certainly is this way with a standard Lutron (1 way) dimmer with LED lighting.

    Thanks for pointing out that the two dimmers in series or however they communicate will probably double the loss of a one way dimmer. I am just trying to account for losses on new house wiring choices.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #6
    Re: 3 way dimmer switch with high efficiiency when dimmed
    Dave Sparks wrote: »
    It certainly is this way with a standard Lutron (1 way) dimmer with LED lighting.

    I think it's exactly the same with 3-way dimmers.

    As Wayne said, the loss inside dimmer itself is very small. If you were dimming big loads, such as big ceiling fans, it could be few W/dimmer (same as with 1-way), but with LED lightning, there will be nearly no loss.

    You can measure when you get them and tell us exact numbers ...
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
    Re: 3 way dimmer switch with high efficiiency when dimmed
    Dave Sparks wrote: »
    I am just trying to account for losses on new house wiring choices.
    Unless you're dealing with the larger 1000 watt and bigger units with heat sinks because their Triacs get warm under heavy load, your losses from the dimmers themselves will be very small. not worth worrying about. The smaller 500 and 600 watt dimmers don't even get warm when powering 100 or 200 watt loads. Wasted power + heat.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #8
    Re: 3 way dimmer switch with high efficiiency when dimmed
    waynefromnscanada wrote: »
    Not much loss in modern switching dimmers, quite unlike the rheostat types of the olden days. On the other hand, the old rheostat types didn't emit RFI...
    Au contraire. I once built a simple lighting console for a set of PAR cans with the old rheostat type rotary dimmers, and every time I dimmed a light, the PA system would start humming. The more the dimming, the louder the hum.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #9
    Re: 3 way dimmer switch with high efficiiency when dimmed
    ggunn wrote: »
    Au contraire. I once built a simple lighting console for a set of PAR cans with the old rheostat type rotary dimmers, and every time I dimmed a light, the PA system would start humming. The more the dimming, the louder the hum.

    In all honesty, you cannot possibly hear RF :D
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: 3 way dimmer switch with high efficiiency when dimmed
    NorthGuy wrote: »
    In all honesty, you cannot possibly hear RF :D

    in all honesty you can if it is radiated and picked up by the amp, rectified, and sent on to other amplifier stages to be heard out of the speakers. i can't tell you how many pa systems i had gotten into in my early days with 11mtrs. bad connections in the electrical system with the rheostat can rectify the ac and create harmonic multiples of it up through the spectrum and ultimately into the rf area of the spectrum thus acting as a transmitter.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #11
    Re: 3 way dimmer switch with high efficiiency when dimmed
    niel wrote: »
    in all honesty you can if it is radiated and picked up by the amp, rectified, and sent on to other amplifier stages to be heard out of the speakers. i can't tell you how many pa systems i had gotten into in my early days with 11mtrs. bad connections in the electrical system with the rheostat can rectify the ac and create harmonic multiples of it up through the spectrum and ultimately into the rf area of the spectrum thus acting as a transmitter.

    You're right. I stand corrected.

    For some reason I thought of RF as 100kHz and up. Humans can hear up to 20 kHz. Bats can hear up to 200 kHz. But officially RF starts at 3kHz, so you can certainly hear it.
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  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
    #12
    Re: 3 way dimmer switch with high efficiiency when dimmed

    You wouldn't be hearing the RF directly, either a low harmonic or just the RF mixing with something else in the audio system to generate audio frequencies.

    I had fun with that in college once. The guy in the dorm room next door was a "music major". He apparently couldn't listen to music without increasing the volume to 11. I had my meager ham radio station in the dorm, and found I could put my mag-mount 2-meter antenna (145MHz) against the wall, run my 5W handheld through an amplifier (boosting to 100W), and the result was most gratifying.

    Whenever he increased the volume beyond reasonable levels, I'd key up the handheld and his speakers emitted a most satisfying LOUD HUM. Pitch was low, maybe 200-400 Hz. He'd immediately turn the volume down. Lather, rinse repeat.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #13
    Re: 3 way dimmer switch with high efficiiency when dimmed
    ggunn wrote: »
    Au contraire. I once built a simple lighting console for a set of PAR cans with the old rheostat type rotary dimmers, and every time I dimmed a light, the PA system would start humming. The more the dimming, the louder the hum.

    Must have been more to that dimmer than a simple variable resistor. A resistor in series with an incandescent light wouldn't emit interference to a PA system unless the whip was making poor contact resulting in arcing.
    Such buzzing is however typical of Triac switching in dimmers, even modern, but low quality dimmers.
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