Control/Dimming Question about budget dimmers...

MrMagLit

Member
Hello,

I'm the TD and guy responsible for selecting the satellite dimmers we'd like to purchase at my high school. New battens, 15A circuits, and 5-pin DMX have all been installed up there, and we'd like to purchase 6 to 12 dimmer packs with 4 channels each. The ability to power all of our 1kW fixtures is very important to us... Also, the dimmer packs will need to take Edison for power in.

Seeing as purchasing that many dimmer packs can be expensive, and our budget is tight, it has been suggested that we look into the DJ market. Leviton/NSI, ADJ/Elation, Chauvet, etc etc...

Is it worth the savings? What are the pros/cons to cheap dimmers? Would you suggest something else?

Thanks!
 
Well, one issue I can already see is the fact that you have 1kW fixtures. Most DJ dimmers can only handle 600w per circuit. Even then, you can usually only put 1800w total on the entire pack.

I would suggest looking at something from Leprecon or maybe Lightronics. If you're running 1K per channel (par 64's?), you really want a capacity of 1200w per channel (absolute bare minimum and even then can present problems), and make sure the total rating of the pack allows you to load all channels. This pretty much eliminates something that you can plug in to an edison outlet unless it has multiple inputs (some Leprecons do have two power cords).
 
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I have to second the Leprecon dimmers that use two 15A circuits. Given your fixture load, they are the one Id suggest. Really what you need is full-sized dimmers.
Les really did nail it right off the bat, with most "shoebox" dimmers you are limited to 1800w over all 4 channels and 500w or 600w per channel. Just not going to handle your 1kw fixtures. Now of course there ARE shoebox dimmers that can take 1kw loads such as the leprecon dimmers mentioned.
Personally I think its time you shop around and see what you can find if price is an issue.

A 15A circuit can handle at very most 1800w, 1440w continuous. If your fixtures are 1kw a piece really thats one (or realistically two not at full) per circuit. A dimmer that uses a 20A circuit clearly has that beat at 2400w (enough for TWO!). You get the picture.

Secondly its great that you have AC and DMX up there. This is handy for portable dimmers yes, but also great for accessories and LED light fixtures.
 
While some shoebox dimmers claim 1800w max, the internal components on them may not be rated to 15A. I have one that claimed 10A/channel, 20A max but it used a 14/3 cord, 10A IEC inlet, 6A switch, and 15A fuse holder. Double-check yours before assuming that you can trust the ratings.

/mike
 
What's your realistic budget?

Here has been my personal experience with several different "shoebox" dimming products:

At entry-level is the the Leviton/NSI D4-DMX. This unit offers four triac driven dimmer channels with circuit breakers rated at 10 amps (1200 watts). They contain modest toroidal chokes that quiets lamps down some. These sell for about $250 from most internet retailers. The main power cord is 6' 14 awg with a standard 15 amp. edison molded male connector. I have regularly run 2 (or sometimes more, but that's another story) 1000 watt loads on these packs and never had any trouble with tripping breakers, melted connectors or other overheating issues. That said, when I set up a rig like this I am almost always the board op. and I am very conscious of not running both 1k loads for at full for more than a few seconds. I'm not sure I would trust that situation in a high school setting. When you lose a channel in one of these Leviton packs, it's just gone.

Jumping up considerably, I also have a number of the Leviton/NSI DDS6000+ packs. These are 4 channel packs with four 1200 watt SCR driven channels per pack. It has significant toroidal chokes and is specced at a ~400us rise time (ETC Sensor dimmers are specced at a 350us rise time) It has dual 12 awg feeder cables that must come from two separate circuits if you want to load them at full capacity. Technically speaking, these are rated for a total of 3,600 watts. However, that is a bit of semantics that comes from the fact that since it has the 15-amp standard edison plug, it's UL rating can be no higher than 15-amps per feeder circuit. If you have 20-amp feeder circuits with edison connectors, and any extension cables you use to get to the packs are 12 gauge or 10 gauge and relatively short (25' or less) I would see no issue loading these with 4 - 1k loads. Price for this pack is usually in the $650 range. If something goes bad in one of these packs, it's generally worth having repaired as they are pretty robust. The University of Minnesota uses these packs for the distributed dimming in their arena theatre.

Next there is the Leprechon ULD-340-HP. These are very similar in performance to the Leviton DDS series. They sell for about $850. Again, you have two 12 gauge input cords that have been down-rated to 15 amps because of the connecter used. Leprechon does not list the rise time of their chokes, but in my experience the filament noise I hear is similar to rack mounted dimmers by the major manufacturers. The two primary advantages of the Leprecon packs are: 1. they are designed to be tree mounted and are super easy to rig. 2. Their SCR driven dimmers are actually rated at 25 amps each. That means that you could actually operate a 2.4k load on ONE dimmer as long as you weren't using the other dimmer fed by the same feeder circuit.

Finally there is the Litetronics AS42D. These packs have basically the same features as the Leviton DDS packs except: they are triac driven and they have smaller chokes with a ~150us rise time. This means that they are slightly noisier and that the dimming circuit is likely slightly less robust in response to short circuits and other voltage spikes. They sell for just under $500. I have not used these packs personally, but they look a pretty solid unit.

So, here is my tome about the products that I would consider to be likely candidates for your purposes.
 
At 15 amps per circuit, you are only good running one (1000w) fixture per circuit. I have to second the idea that most cheap dimmers are only good to 600 watts per channel even if their rating lists "10 amps" per channel. Most of these packs use a 15 amp triac, which does not provide reliable headroom. You need to establish that any pack you would use contains triacs or SCRs with a rating of 25 amps each. I have replaced a ton of those 15 amp triacs that blew on 1000 watt loads. Although there is a drop-in 25 amp triac that fits most of those packs, any such modification removes the UL approval. Which brings up a second point. Make sure the pack has approval or certification before you buy them. (Not just a UL sticker on the power cord.)
 
I've been thinking about getting some Chauvet 6-pack dimmers, $280 each
http://www.parts-express.com/chauvet-dj-pro-d6-6-ch-dmx-dimmer-switch-pack--243-7274
Whenever they say "10 amps per channel" as compared to 1200 watts, I get a little concerned that they may be using the 15 amp triacs. To me, it is kind of a subtle hint. Have never had one of these open, so I can't be sure. Would work fine with a 575 S4 but I wouldn't plug a 1kw par into it. At $280, my bet is the cheaper triac but there is often no way to tell short of opening it up!
 
Whatever you do, With only 15amp circuits, don't spend any extra money to get a 4-6 channel pack. Even if you had 6 channels that could run 1k fixtures, you still could only use one fixture because of the 15 amp circuit it is plugged into.(or one per section of a dimmer pack if it has 2 power inputs)

Not many shoebox dimmers can run 1k fixtures, I cannot think of any off the top of my head. It wont be cheap, but a small dimmer rack and some soca cable to run power where you need it might be better.

How many fixtures do you have, and what locations? Where is power coming into the building? Is there a disconnect available for portable rack, or space for an installed rack?
 
Also, What 1k fixtures are you using? I cannot think of many 1k fixtures besides Fresnels that are really worth spending much money on these days. If they are older lekos or pars, I would think about holding out for more money to be available, and upgrading those fixtures.
 
It wont be cheap, but a small dimmer rack and some soca cable to run power where you need it might be better.

How many fixtures do you have, and what locations? Where is power coming into the building? Is there a disconnect available for portable rack, or space for an installed rack?

To piggyback this post, have you considered 19" rackmount dimmer packs? These generally have higher capacity for not much extra cost, as long as they can be located where there is plenty of power. The ETC SmartPack is one example, but there are many other models and manufacturers out there.
 
Have you thought about adding LED PARs instead of adding dimmers? There are some decent choices starting down around $350. You might be able to get a grant from your district, local power company, or city government to help you pay for replacing you 1K PARs with LED's making it more doable on your budget.
 
Whatever you do, With only 15amp circuits, don't spend any extra money to get a 4-6 channel pack. Even if you had 6 channels that could run 1k fixtures, you still could only use one fixture because of the 15 amp circuit it is plugged into.(or one per section of a dimmer pack if it has 2 power inputs)

An electrician may be able to change your outlets (and the breakers feeding them) to 20A on the existing wiring. And maybe not.
 
I'm surprised that they're 15A circuits in a commercial building. Seems like code generally called for 20A as a standard.
 
I'm surprised that they're 15A circuits in a commercial building. Seems like code generally called for 20A as a standard.
Funny you should say that. I don't know of any specific code that would prohibit a 15 amp circuit in a commercial building (maybe somebody else does), but I also can't remember ever seeing a 15 amp circuit in any modern commercial building either. Odd that they ran 15s for the new wiring.
 
Funny you should say that. I don't know of any specific code that would prohibit a 15 amp circuit in a commercial building (maybe somebody else does), but I also can't remember ever seeing a 15 amp circuit in any modern commercial building either. Odd that they ran 15s for the new wiring.

Maybe it's a trick of the wording ("branch circuits shall use minimum #12 THHN wire...") or something like that, which would imply 20A? I can't recite any particular code either, but I can ask a few journeyman electrician friends. Maybe @BillConnerASTC would know. I wouldn't be surprised if the OP's space is wired with #12.
 
Maybe it's a trick of the wording ("branch circuits shall use minimum #12 THHN wire...") or something like that, which would imply 20A? I can't recite any particular code either, but I can ask a few journeyman electrician friends. Maybe @BillConnerASTC would know. I wouldn't be surprised if the OP's space is wired with #12.
You might be right. If you have to run #12, then why not 20? Breaker is the same cost. The only limiter would be if they used dedicated 15 amp receptacles and there is only one per circuit.
 

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