Control/Dimming - Dimmer Wiring

[marcusianl]

During the renovation at our school's theatre this past year we received a new Sensor+ Dimmer rack. However, when wiring our FOH catwalk, they didn't run new Dimmer lines, they just ran new cable through the existing ones, so we only have 6 Dimmers on our catwalk (although we have 18 instruments and 24 outlets). Is there any way to increase the number of controllable dimmers without running more cable? I saw something on ETC's website about a Dimmer Splitter. Would that do the job?

-Marcus

[pdk]

It depends on what kind of fixtures you have and what your budget is. Dimmer doubling basically splits the power coming out of the dimmer into two independent 77V circuits. As far as I remember, dimmer doubling works only with ETC fixtures and you have to switch the fixtures to be doubled to a special 550W/77V HPL lamp and a special kind of twistlock connector in addition to buying the dimmer doubler itself. So basically yes, it can work in some cases and is cheaper than running new cable, but depends a lot on your exact setup. It only works on US supplies (115V 60hz) as I recall, so that might limit it as well. But generally, if running more cable is not an option because of cost or the space, then dimmer doubling can work.

[Footer]

Its called dimmer doubling. Essentially, you put 77v lamps in the lights (must be S4). You then attach a multiplex two-fer to the lights, and plug it in. The dimmer has to be told that it is multiplexed. You can two-fer off a multiplex as well.

Now... that being said... I hate dimmer doubling. I can not tell you how many channel checks I did in college after a 300-400 instrument hang and here "pop, pop" with 77v blowing in lights hooked up to 120v. If its not organized well, it can become a real headache real fast. It is however much cheaper then running new dimmer lines.

[derekleffew]

Originally Posted by pdk

...and is cheaper than running new cable, ...

Originally Posted by Footer

...It is however much cheaper then running new dimmer lines.

Disagree with the above as it depends on the circumstances. If the dimmers already exist or a less than fully-populated rack, and space available in the conduit, dimmer doublers would cost more, when one figures the cost of the lamps, connectors, DimmerDoubler, and the forever hassle of patching, non-standard lamp, etc.

#12 (or #10) THHN is inexpensive and I'd rather pay the labor once to pull it than for the rest of the dimming system's life (10-30 years?) deal with dimmer doubling.

[JD]

Have to agree with Derek. There are limits to the number of runs you can pull through a given conduit size, but even having additional conduit installed may be cheaper. Pipe is cheap, and unless they have to go through a block wall, they can simply duplicate the current bends and path taken. Depending on the school and the turnover, newbies would have to have DD explained to them, otherwise the consumption of lamps may go through the roof.

[marcusianl]

We are running on S4's and it's a pretty simple setup (only about 50 instruments hanging currently) but I'd like to be able to avoid the hassle and paperwork of requesting new lamps, different connectors, and the doublers, so maybe I'll ask about wiring new dimmers. Would it be a horrible idea to run the cable along a wall without being in an actual wire tube? The way our space is set up we could potentially run cable through a hallway into our FOH catwalk. It would probably be about a 200 foot run, maybe a bit more.

[jmabray]

You would be in violation of your electrical code not running it in EMT (Empty Metal tube) AKA Conduit. Theatres get away with running extension cables from one outlet to power a fixture because it is a temporary set up. When you get into running circuits like you are talking about, you are moving from temporary to permanent and it must be done according to code.

[marcusianl]

Figured as much. I highly doubt we'd be able to get the school to contract someone out to run the wiring seeing as the work order for the renovation that just happened was placed in 1992. Gotta love bureaucracy :/ For now I guess we'll just have to deal with it. Thanks for the help everyone

[derekleffew]

Weren't you the one asking what to buy given a windfall of a few thousand dollars? While not as glamorous as moving lights, investing in infrastructure is always good. I'm guessing adding six more dimming circuits could be right around $1500-$2500.

I realize there may be politics and procedures involved. In some cases it may be possible to buy equipment, but not improvements to the building, or the reverse.

[marcusianl]

Yes, I am the same person, and that's exactly my dilemma Derek. My administrators don't know that being able to control my lights in sets of 2 or even 1 as opposed to 4+ is far more important than new toys to play with, and seeing as I'm only a student I can't exactly tell them they're wrong. They respect that I'm one of the few people in the school who know how to run things, but I still have to bow to their authority. They honestly believe that the renovation we got this year transformed the space into some magical world where anything is possible, all you need are the fixtures. While the renovation did a whole lot of good (we had about 3 working dimmers and one working mic) it wasn't the best we could've hoped for considering how long the wait was. Anyways, I'll talk to my Director/Department head and see if the Admins would let more infrastructure work fly, but I doubt it. They want to see pretty things, not efficient things.