Multi-location dimming, LEDs, minimum load...

14 years ago

Hello!

We like the dimmers, but several rooms have light-switches at multiple locations.

It appears, Lutron are currently the only ones, offering "true multi-location dimming" Â where the light can be dimmed up or down from any of the locations, rather than only from one.

However, it seems, Lutron's minimum wattage is 40W. We are using the 12W LED lights, which can be dimmed down to 25% (or 3W). Am I right suspecting, Lutron will not be able to dim that low, unless there are 13 such lamps on the circuit?

In fact, if I'm reading this right, it will not even work at all, unless there are 4 such lamps on each circuit... Or am I misinterpreting something?

Thanks! Yours,

doofus

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Comments (5)

kurto
14 years ago
Which model Lutron dimmer are you investigating?
doofus
Original Author
14 years ago
Which model Lutron dimmer are you investigating?

Oh, I don't really care, which one Â whatever works... Apparently, the MAELV line is what I need for the "master" dimmer (the one, that, actually, controls the light). It is named "low-voltage" (ELV stands for Electronic Low Voltage) which is a misnomer: it should read "low-wattage".

Apparently, MAELV's minimum load requirement is only 10Watt (not 40 as with the rest of of Lutron's Maestros) and so it can deal with the small number LED fixtures. It is expensive, though.

Unfortunately, Lutron would not state, that it will work with CREE's CR6C lights, although a nearly-identical Cooper/Halo ML706830 downlight is listed as compatible with MAELV-600 (and some others). The Halo's color temperature is only 3000K, and my most significant other wants CREE's 3500K (or even more)...

Going from the other direction, CREE's own compatibility list doesn't mention Lutron at all, even if CREE people on the phone are quite adamant, that it will work just fine.

Everyone you speak to, points out, that the state of the LED-lighting industry is currently still in a flux and the only way to ensure compatibility is for manufacturers (or even consumers!) to test it for themselves...

Crazy, is not it?
doofus
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Thank you, David and brickeyee! I know I can always count on your expertise. I have another question: Leviton magnetic dimmers vs. lutron magnetic dimmers. There are quite a few brands of magnetic low voltage transformers listing Lutron magnetic dimmers as their approved dimmer, but not leviton magnetic dimmers. I specifically asked Juno whether their magnetic transformer works with other brands of magnetic dimmer, for example, leviton. Their answer is "Unfortunately, at this time, we do not have any Leviton dimmers approved for use with the magnetic TL575 driver. " So basically no information there. I can see leviton is not listed myself! One of things I learn from this forum is that a magnetic dimmer should work with a magnetic transformer. Any reason why I shouldn't use a Leviton magnetic dimmer with a Juno magnetic transformer? Lutron is much more expensive than Leviton, what I am trading off by using a less expensive leviton? I am going to post this as a sperate posting just in case you don't see this.
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One frustration you are likely to discover is that 60 watts might not dim well. It will come on nearly full and not dim to low level. The only way is to add more load to the 110 volt side of the dimmer. I did not fully understand the post but my 0.02 is only from experience. Most dimmers need a minimum load to work smoothly over a 0 - 100 % range. I think someone said you can't dim the transformer? Unless it's against code I think there's no reason not to. There is a bit of power loss in the transformer compared to not dimming but not enough to create any problems in my experience. Good luck. I'll check back to see where this goes. Andre
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" There are two issues for CFL/LED/LowVoltage apps and the rapid rise time isn't one of them. " The chopped off low voltage (TRICS do not turn on till at least 0.7 V and many closer to 1.0 V) causes heating in inductors as does the delayed turn on ad sharp steps produced in the current waveform. Even at 100% on time, the voltage loss is present on every AC cycle. The delayed turn on also produces a sharp rising edge 9and by this means a lot of harmonics of the 60 Hz). The impedance of an inductive element rises with frequency, meaning more power is dissipated in the part heating it up. It is not hard to design AC-DC power supplies to cope with TRIAC switching, but it needs to be done if the supply needs to operate correctly. CFLs have even more problems, since they both rectify the incoming power, and then use switching techniques to boost it up to many hundreds volts for starting, ad then keep it provide a lower (but still high) voltage ft operation at tens to hundreds of kilohertz frequency (instead of the power line 60 Hertz). Dimming fluorescent lights has always been a problem. Minor dimming (5 to 15) is not hard, but after that it gets worse and worse. Leakage in the off device state also can produce odd effects on electronic ballasts. They store up the small leakage charge until the voltage stored is high enough to start a strike to turn the device on. Then the power is not adequate to keep the lamp on. It appears as a quick starting flash at intervals depending the loads and leakage present. Some LED switching supplies can respond in a similar way. while others just make the LED glow dimly all the time. Switching to the trailing edge for cutting the current allows the parasitics in the circuit to limit the fall time of the current resulting in fewer harmonics being created (and less inductor heating). The problem for the consumer is that the two devices (dimmers and lighting power supplies) have NOT always moved together. A more complicated trigger circuit on a TRIAC can use the trailing edge, but they are far from trivial to design and take significantly more parts. You have to pull current out of the gate to force the shutdown (and the negative gate current can depend on the load on the TRIAC, generally unknown and changing as the light dims).
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mike_kaiser_gw
14 years ago
Maybe you should wait a bit on the LED lamps for the technology to stablize before migrating. At $80+ a pop, it seems it would take quite a while to reach break even. Regular incandescent dimmers are cheap enough to toss them (or sell them on eBay) after you're through with them.

I looked briefly at Luton's site and it seems you need a special module for LEDs. Maybe not.
davidrt28 (zone 7)
14 years ago
funny I came to this forum with a somewhat related question...
Does anybody make a "smart dimmer" that can detect when the load is not a standard dimmer load (i.e., incandescent bulbs) and give up dimming them?
I have a ceiling fan that was put on a dimmer - probably a bad idea period. I never use the fan. With incads. bulbs, the dimmer worked of course. I've converted to CFLs. With the dimmer set at max, they worked reliably.
I recently had a new heat pump put in and it seems to be kicking back some harmonic noise or DC into the house lines. (yeah I should probably have that checked out...) Basically the CFLs go berserk at the "full" dial position when the AC/HP runs. They start flashing and making a high pitch humming sound. I have to adjust them down to the 1/2 position and they are steady again. When the HP turns off, the 1/2 position makes them go crazy! It's a no-win situation LOL.

The obvious solution is to replace with a switch...yes...I know and will probably do that...I just wonder if there's some kind of fuzzy-logic controlled, fault-detecting dimmer for these situations.
Tom Pultz
14 years ago
We have Leviton Acenti master and remote dimmers in many locations so I would not say Lutron is the only one that does this. The kitchen lights are a 5-way circuit with 4" magnetic low voltage MR-16 Halogens which can be dimmed down to the point they are barely on. We are using 3500K bulbs in the dining room and family room and 4100K bulbs in the kitchen, which makes everything nice and sparkly.

I'm not about to change to LEDs just to save a few watts of power since the cost of the magnetic LV lights and dimmers was considerable. Our lights are generally dimmed most of the time anyway unless we are working in the kitchen, so the power use is minimal. I doubt we'd save that much. I certainly did NOT notice any savings going to CFL bulbs in other locations.

I hope the LEDs work out for you as they will probably be forced down our throats eventually.

Multi-location dimming, LEDs, minimum load...

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kurto

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Multi-location dimming, LEDs, minimum load...

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doofus
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