2 hopefully basic dimming questions

Well, it's an "it depends".

Really, dimmer parks are designed to work with ParCan lights using traditional incandescent bulbs that can be dimmed, or other bulbs that can be dimmed by varying the voltage.

I would NOT recommend using dimmer packs for Christmas lights, although you could. I'm just not sure if they are rated for dimming applications. I would suggest that you see if you're using a newer model DP-DXM20L, because I have the older ones. The newer ones can be set for switching/dimming on a per channel basis, whereas the older ones are strictly dimmer packs.

If the christmas lights are not recommended for use with dimmers, run them at 100% off the dimmer.

DO NOT connect intelligent lights(those with DMX functionality) to dimmer packs EVER!! Also, if you're planning to use Hi-Tech FX with dimmer packs, you need to run those channels in switched mode, not dimming mode. High tech FX need full voltage to properly operate. Lower voltage will cause failures to the fixtures's internal components.

Are you going to hurt the dimmer? Probably not. Do keep in mind this is rated for indoor usage, so please keep it dry.

Are you going damage bulbs by running your par cans very dimmly? Maybe, but the issue there is that these are readily available and cheap, so it's no big deal if you have one fail for any reason.

Chances are you'd find out if something wasn't OK because your house burned down. The odds are in your favor of simply burning out bulbs over any other sort of drastic reaction. Some bulbs that are underpowered may fail faster, some may not.

Hi Bill and welcome to the forums.

Christmas lights are completely dimmable as long as they aren't LEDs. I have done this a lot for different shows. An incandescent lamp is fully dimmable in a dimmer pack. I have likewise had regular old light bulbs that people use at home plugged into dimmers as well for shows.

As for your second question, running lights below their maxim output actually extends their life. So running par cans at say 80%, will last longer then running at 100%. Also, bumping lights shortens their life as well. You are more likely to blow a lamp on a bump then dimming it up over time. Sudden in-rush currents don't give the filament time to adjust and might break it.

However, running lights below maxim output increase lamp sing and dimmer buzz. It is the greatest at 50% since that is where the sine wave is chopped the most extreme. This doesn't hurt dimmers or lamps however, just annoying in sound sensitive environments. Likewise, if audio it catching dimmer buzz, it will be the loudest at 50%, and basically none at all at 0 or 100%.

Some idiot around where I live burned their house down a few years ago putting christmas lights on dimmers. No major details were given on what type of lights or what actually sparked off the fire. News and media just spit out dimmers and christmas lights.

Remember, safety FIRST!! Not "Safety Third" as Mike Rowe of Dirty Jobs says.(BTW, that's a cool show, I recommend people tune to Discovery Channel on Tuesdays to watch, and no, I'm not being paid or prompted to plug his show)

My guess is the guy overloaded the dimmer. And I doubt it was a professional dimmer as well. Dimmers you get at Home Depot or Lowes have no sort of limiter on them or fail safe. Professional dimmer packs have fuses and/or breakers to keep from overloading. Likewise, the stuff that is in professional dimmer packs are rated for more then what the limits are on them. This is in case the fail safe fails.

Another factor could be the fact that Christmas lights use cheap lamp cord vs SO or SJ cable. So he could have overloaded it that way as well.

Well, I'm not going to guess which way this idiot chose to roast his chestnuts over his open fire(of a house). Doesn't really matter.

The best point you brought up is to use PROFESSIONAL dimmers and quality cabling. Both are key safety factors. That and do the math to prevent overloading breakers.

People go nuts over two holidays: Halloween and Christmas. I suspect it to be the same in a lot of places. With some of the insane displays, it's a miracle more houses don't burn down.

I don't get into holidays. It's just another day of the week for me.

Go safe and sane in decorating!

wow thanks for all the advice guys,

yeah i'm well aware with the intelligent movers, it's just the different incandescents i was a little more unsure of. it's for a christmas show where the lights are already built into a bunch of christmas trees that someone else owns. i'm only doing it for a few minutes at a time anyway for a dramatic effect. i'll have to make sure i dont overload the channel as it's easy to get carried away (i'm assuming 1W for each bulb). i'm a little confused about the power rating on the dimmer though...if it's 10A per channel, then how can it be 20A total if it's a four channel pack? does it matter if it's in 1, 2 or 4 channel mode?

i'm glad serraava brought up the lamp sing/dimmer buzz thing because that's kinda why i brought up the par bulbs too. i'm somewhat new to working with my own pars now so i'll try to have more bulbs available.

definitely cleared a lot up, if anyone knows about the dimmer rating i mentioned then that would be great too..but thanks again

I'm not sure how the dimmers are wired or their actual ratings.

I have 2 PP-DMX20L's and 3 DP-DMX20L's,an Aviator SP-8(8 channel DMX dimmre pack, which is essentially 2 newer DP-DMX20L's in one case, and 2 power plugs), and 2 Chauvet power packs. They all essentially work the same:

No single channel can deliver more than 10 amps, and no power pack can deliver a total not exceeding 20 amps(with the exception of the Aviator SP-8 which can handle 40 amps since it's a double...). BUT: 15 amps is 1800 watts and the plus is a 15-amp Edison, so I am not going to try to pull more than 1800-watts through the dimmers. 20 amps is 2400 watts.

As far as actual draw: while you could put all 4 channels at 100%, unless the stuff drawing voltage is exceeding ratings, you're fine. Let's say you have 4 300-watt fixtures, one on eahc channel: Maximum draw is 1200 watts, whcih is below 1800 watts. At around 3 amps per channel, you're still fine.

1,2 and 4 channel modes let you choose how you want to use things. I won't waste time with a "why this or that" here, it depends on your requirements and configuration. Personally, 4 channel mode is want I want and what I need.

With those strings, just check the package. I think a typical string of 100 is like 25 watts for those tiny bulbs. I think the outdoor rated ones are the same as well.

I'm not into holidays. This time of year throws me into deep depression. I'm focussing on a lighting design for a shadow-cast type performance right now, keeping my mind off the holiday insanity. It's Repo: The Genetic Opera. Ain't my cup of tea and the dark nature sure don't help, but work is work.