DMX Dimmer Pack

ADJ makes exactly what you want, but if you're planning on running 20 cans of it(of any sort), then you're going to be sadly disappointed as it will exceed the power handling of the unit.

Well, depends on how you do it. Considering, what is it, watts/volts=amps?

I use this rule: Every 150-watt Par38 is an amp. That's not accurate, but works quickly. 4 is 4 amps. 5 is 5 amps(OK, we're past that, get over it).

Now, assuming 4 colors at 5 per channel, that's 5 amps. Now, you can do easily 2 channels full on, assuming that is 10 amps, which is isn't. That's 1500 watts, which is 12.5 amps. Dimmer pack is rated at 10 amps per channel, so you're so far good.
Now, running another 5 lights off another channel? Well, that's another 5X150=750.
Simple math: 1500+750=2250 watts, and a 15-amp outlet is 1800 watts, but that IS 18.75 amps. So, adding another 750 watts for 5 more lights on the 4th channel for a total 3000 watts. That's 25 amps. Ouch.

Lowering the numbers to 100 watt bulbs, you end up at 2000 total watts, which at full load is still under 20 amps but OVER 15 amps, and the plug is a 15-amp plug, not a 20, but I'd say by the wiring, it could go 20 amps no problem. Still, the until itself won't handle the load at full load. Maybe 2 channels at full load, but I wouldn't push it. Worse case is you blow a fuse.

So, it really depends on what you want to do.
The ADJ DP-DMX20L is a great bit of equipment.

Also, you have the following choices:
You have a DMX controller, so you can use that to over-ride the generally boring programs built into the dimmer pack. All you really need to do is determine how many channels you want to set the unit up for: 1,2 or 4, and the start channel.
Or use their programs built into the pack.

I second the DP-DMX 20L its a great unit. I used to own six of them for my stage show.... Now I am switching over to NSi DDS-6000's

haha, so how bad would your head spin if i told you i was actually thinking of using 56's rather than 38's?

your solution would be multiple dimmer packs run off a dmx board... this will give you a lot of flexibility as well as allow you to program tailored shows for any need/effect you want to create.

You think Par56's or Par64's are going to spin my head?

Puh-lease!! I'll go count the Par64's in the rig I am going to be working with tomorrow, and I'll get back to you. I think it's 48 or 60 per truss, and there's a front and back. I could be wrong though, I'll have to go check a picture. Check out my web site and find a Cache Creek show, it's one of those.

You want to run 20 Par56's on a single 4-channel dimmer pack? OK, got fuses? Blow 'em if you got 'em!!

Seriously, as another poster said, get multiple dimmer packs. You'll get more flexibility and capability. BUT: again, don't run them off the same circuit or you'll end up popping the breaker. If you feel the need to take this sort of risk, then I strongly recommend you take matters into your own hands. By that, I mean: get power strips or power units, such as those made my a company that ends with man and starts with Fur, but has nothing to do with guys or fuzzy animals. Let the AC unit pop it's internal breaker, then you can reset it. Better to do it this way than have to keep bugging some club or restaurant owner to reset their breaker. Better to pop your gear than venue gear, even if it's just a simple reset procedure. I run into problems all the time since I generally deal with induhviduals who have no concept of conservation of electricity. It's basically "whatever I'm doing is more important than what you're doing". Anything you can do to protect you, yourself and your gear from having outside interference, DO IT!

Trust me, been there, done that. I got these "contractor" rated power strips at Home Depot for cheap and they are solid as you know what, and my lighting guy kept popping the breaker on the power strip. In the case of these, it's a simple "power cycle" to reset. With some others, you have to press a reset switch. As long as you're not replacing fuses every 2 minutes, that's good. Just look for a power strip with a breaker function and you SHOULD be fine.

As far as Par56's, Par 48's, Par64's, well, I've given the math, you can calculate the rest based on wattage draw of the bulb.

Hey Chris, what were you using to color your tall boxes and your scrims? color washes from behind or par cans?