Control/Dimming - Duplicating/repeating circuits in a raceway

[Footer]

I am the proud owner of a theatre that has two-fered raceways and,even better, twofered floor pockets. Just wondering what others think of this most wonderful practice. My biggest gripe about mine is how they are twofered, there is NO logical reason to why they placed circuits like they did. I have floorpockets that are ganged togther accross stage from each other. I have circutis that are a upside and backwards mirror of each other, but are offset by like 8'. It is by far the most annoying thing that can happen. Just give me a circuit, and I can cable the rest. Ug.

Anyone else annoyed with these type of setups? Anyone else figure out how to use their setup to its fullest?

[icewolf08]

I have seen raceway twofering where there might be 15 circuits on the raceway and it goes 1-15 and then repeats 1-15, but from what you describe it sounds like yours go 1-15 and then 15-1, which I wouldn't understand. I don't really get the floor pockets though. However, it sort of makes sense from a modified McCandless way of thinking. In that you have ganged units into each area across the stage.

I don't know if that is any help at all.

[porkchop]

While I can't comment on the backwards/mirrored nature on your pockets and raceway. They did a similar thing to your two-fered circuits in my old high school.

The rational there was that the dimmer purchase was a two step process. They got all of the copper ran and installed 2/3 of the dimmers at initial construction. Then they did some two-fering since they had 50% more copper runs than dimmers. Things like FOH wash positions and all our floor pockets got two-fered together.

I believe that since I've left they finally bought the last 1/3 of the dimmers and there are no longer any built-in two-fers in the auditorium. This may not be why they did it in your house, but that's why they did it in my old one.

[derekleffew]

There are two philosophies on this. One is that the circuits are laid out to best suit a "house plot," usually one ill-conceived and often discarded immediately. The other is to place repeating circuits in locations highly unlikely to be used simultaneously (Pork's example of the FOH wash and floor pockets is a prime example).

A 40' raceway with outlets every 18" is 26+ circuits. Most architects/electrical engineers feel it better to duplicate some or all circuits rather than provide 26 individual circuits/dimmers. As the cost of high density dimmers racks have come down in price, this practice is dying, albeit slowly. I'm not agreeing with, or defending the practice, as I, too, would rather have one, and only one, outlet for each dimmer.

Planning the circuit distribution layout on a stage is more art than science, and one that few get correct. I believe I've said before that I don't think I've ever been on a stage where the circuit layout is exactly to my liking, even on a relatively small stage with 1000 dimmers.

[Footer]

Its not even a reverse mirror really, it goes beyond that. Here is my 2nd elec, from SR to SL.

89 90 85 86 87 88 91 73 74 75 76 77 78 79 80 81 82 83 84 89 90 85 86 87 88 91

These are fairly new ETC raceways. I have 170 something dimmers in this space, so its not like I am short on power. It is very annoying to deal with. Its obvious to see they want the pipe ends ganged, but really who does that? Also, can anyone even give me a stupid reason why they had to skip all over the place?

[gafftapegreenia]

As I understand, a lot of "new construction" today is still based upon old methods and theories. Of course there are the repeating circuits that would have been perfectly suited for strip lights. As for the mirror floor pockets, I've heard this explained as an old concept that what a design most wants is the same color of light coming from both sides of the stage at the same time. (ugh). Repeating circuits in the cats are also part of the "old theories", aside from limiting dimmer costs, namely that mccandless rules, so might as well design your theatre that way. Take the example of a recently built theatre in Detroit. A pile of circuits on the cats, but very, very limited and repeating circuits onstage. Seems to me most "modern" designers are constantly crying for more on stage circuits. Again, I think it's just more carryover from older styles of design and lighting practice, but it just wont die, and theatre consultants seem to be doing their best to keep it alive. As Derek said, as dimmer racks have come down in price, the older, repeating circuits are dying a hard, long fought death - they need to just hurry up and die already. Lighting designers, they always want more control control control.

[sk8rsdad]

My guess is the electricians who wired the place connected wires at random, perhaps with some thought to mix-and-match between bundles that were pulled together. When they pull wire into the conduits they tend to pull them in multiples based on the number of reels they have on the go, often multiples of 3 given 3-phase distribution.

It may be that the circuits are twinned in the dimmer rack, or it might be that they are twinned in a splitter box somewhere but if you ever get the chance to look inside you'll see a lot of wire bundles that all look very similar. If they are twinned in the rack then it's not too big a job to get a qualified electrician to take the time to reorganize them in whatever you consider a more reasonable manner.

My theatre is wired dimmer-per-circuit in groups of 6 (2 circuits per phase) with some twinning, using Socapex (stage circuits) and/or NEMA L5-20 receptacles depending on the location and age of the the last upgrade. With an inventory of fan-ins and fan-outs we can get power to pretty much any location in the theatre with minimal fuss and cable.

[porkchop]

Originally Posted by sk8rsdad

My guess is the electricians who wired the place connected wires at random....

Ok while the rest of your post has merit. My common sense, and my experiance with licensed electricians, argues against the idea of random. For a few reasons:

• Long cable runs are hard to trace to begin with, randomizing and not labeling before you pull the cable is access work.
• Random increases the possibility of errors, and the kind of power a dimmer often has mixed with errors is not really a fun idea.
• Dimmers are often organized in the rack in a seemingly random order to help with load balancing. A field electrician adding another step of random with limited knowledge of how the theatre plot will be setup would be counter productive.
• It just doesn't seem like a good idea IMHO.

If I had to guess I would say that the seemingly odd order of your example cat is actually to fit the house plot to the board nicely. One of many possible examples of fitting your example cat to a board would be 85-88 FOH warm wash, 89 + 90 FOH Cool wash, 91 Patterns, 73 - 84 utility circuits. One can make all kinds of assertions about this setup, but if the original control device has a convinent way for this pattern to work out (say rows and/or sections of faders or on the screen depending on age in install and control device) I would say that you have found a theatre that was designed to fit the plot and the plot was designed to fit the control device.

[lieperjp]

My raceways also have some twofering done, as well as some threefering and fourfering (actual words?)

For instance, my first electric goes:

26 34 33 32 31 25 24 34 33 32 31 23 22 34 33 32 31 21 20 30 29 28 27 19 18 30 29 28 27 17 16 30 29 28 27 15

I found it annoying at first, and don't get me wrong, I still would rather have it done singularly, but I find that as long as I plan efficiently the twofering saves me time programming submasters/groups. I think it was done this way to save money on dimmers. For instance, on stage we have 112 outlets but only 59 channels. I would think this saves a lot of money. Sure, sometimes I have to balance power out to prevent blown breakers, but that does save a lot of money and maintenance time.

However, my electrics seem to follow a logical order. Yours, however, would drive me crazy!!!

[willbb123]

my highschool stage was twofered oddly also. I finaly figured out that it was designed for a REP plot. The theater i work at now has one dimmer per plug. This works great on the on-stage electrics, where I have basically every plug filled. But in the cat and booms there are 20 to 30 circuits and corresponding dimmers that I am not using.

At my high school I would of perfered if every plug had its own circuit number, then there was a patch bay where I could patch the circuit to the dimmer. There was like 40 some plugs but only 24 dimmers so I could have patched 2 lights together.