# Understanding Touring Dimmer Rack Patch Panels



## NateTheRiddler (Feb 15, 2019)

Good morning, CB! It’s time for Newbie Nate’s Question of the Day!

Today, I’ve been studying dimmer racks and modules, in an attempt to get a better electrical grasp of what’s going on in my PAC. One of the things I’ve seen worked on (and mentioned) are “patch panels” (correct me if the term is incorrect) located on the back of touring dimmer racks such as the ETC CEM+/CEM3.

Brace yourself for Pain from Hard Face Palming, please:
_How the *&$% do these things work?!?
_
Now, mind you, I’ve been googling trying to find instructions on how the signal flow works from rack control to those small connectors on the panel, and then from there to the circuit outputs that will eventually become a touring rig of conventionals. Unfortunately, I don’t have a touring rack in my PAC to play with and figure it out on my own. And, lastly, I’ve scoured the forums here and found plenty of technical troubleshooting, but I barely understand the dang thing.

If anyone has an article tutorializing me on how to patch a touring rack, I’d be beyond elated. Of course, if this is one of those RTFM sorts of things, please do point me to the right point in the manual, because I read the entire CEM Configuration Manual and couldn’t find info on it. T_T

Thanks for those of you who took enough Tylenol to answer this post!


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## derekleffew (Feb 15, 2019)

See here: https://www.controlbooth.com/threads/etc-sensor-patch-bay-touring-rack.40366/ .

At the fixture, a light is plugged into one of six circuits on the multi-cable break-out. Let's say the second circuit.
The break-out is then plugged into a Socapex-style multi-cable that happens to be labeled [R1]A.
At dimmer Rack#1, the male end of the soco is plugged into outlet labeled A.
Inside the rack's patchbay, circuit A2's single banana-type plug is inserted into Dimmer#1.
At the console, dimmer#1 is soft-patched to control channel#1.
Bring up channel 1 to full, DMX tells the CEM to bring up dimmer 1 to full.
Electricity flows from the dimmer via the circuit to the luminaire.

Notes:
The hanging cords are the hot conductor s of the circuit s and the jacks are the dimmer outputs.
The pin patch only carries the hot wire; all the neutrals are bussed together inside the rack.
Only the Socapex outlets are patchable. The 2P&G receptacles on the rack are direct to dimmer.

Any questions?


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## NateTheRiddler (Feb 15, 2019)

derekleffew said:


> See here: https://www.controlbooth.com/threads/etc-sensor-patch-bay-touring-rack.40366/ .
> 
> At the fixture, a light is plugged into one of six circuits on the multi-cable break-out. Let's say the second circuit.
> The break-out is then plugged into a Socapex-style multi-cable that happens to be labeled [R1]A.
> ...



Wow!  Thanks a bunch! That completely nailed what I was trying to understand about the system.

Only one question, a conceptual one:
I see on the patch bay of the CEM that each dimmer has two “banana-type” sockets (correct terminology???). So, if I took two fixtures, both on [R1]A, and occupied both of the dimmer 1 slots, then those fixtures have been essentially cloned, correct?

Also, as a test of my own knowledge, the signal flow is:
Desk —> CEM —> Selected Dimmer —> Chosen Socapex Circuit via banana-type connector —> Socapex breakout —> Fixture assigned to numeric circuit


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## derekleffew (Feb 15, 2019)

NateTheRiddler said:


> Only one question, a conceptual one:
> I see on the patch bay of the CEM that each dimmer has two “banana-type” sockets (correct terminology???). So, if I took two fixtures, both on [R1]A, and occupied both of the dimmer 1 slots, then those fixtures have been essentially cloned, correct?


Not conceptual at all. Two fixtures, plugged to A1 and A2 on the break-out and occupying both holes (some racks have four holes per dimmer output; touring racks are very customizable when ordered) of dimmer 1 are said to be "two-fered at the rack" (using two circuits) as opposed to being "twofered at the light" or "two-ferred on the pipe" (using one circuit). I wouldn't use the term "cloned" as that generally means substituting or adding moving lights not conventionals.
Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots).


NateTheRiddler said:


> Also, as a test of my own knowledge, the signal flow is:
> Desk —> CEM —> Selected Dimmer —> Chosen Socapex Circuit via banana-type connector —> Socapex breakout —> Fixture assigned to numeric circuit


That's it! Viola.


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## NateTheRiddler (Feb 15, 2019)

derekleffew said:


> Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots



Thanks for the terminology corrections; I’ve discovered one of the things betraying my ignorance despite my experience is my poor vocabulary, misusing terms and such. I appreciate the corrections so I can make better communication effort.


derekleffew said:


> That's it! Viola.


Magical! Thanks for the help; guess I’m adding your name to my USITT/LDI “I owe this person a beer” list.


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## derekleffew (Feb 15, 2019)

NateTheRiddler said:


> Thanks for the terminology corrections; I’ve discovered one of the things betraying my ignorance despite my experience is my poor vocabulary, misusing terms and such. I appreciate the corrections so I can make better communication effort.


Socket. The base is part of the lamp. 
Spend as much time as possible in the wiki. 
Most people will overlook transgressions such as calling a SourceFour a Leko, bulb/lamp, lectern/podium; but those who know will still judge you for it.


gafftapegreenia said:


> And this is, I think, at the heart of this discussion. We work in an industry dominated by people that use terms incorrectly, often because of a simple lack of knowledge. As professional entertainment technicans, it is our job to know the proper terms, know what they apply to, know the standard "generic" or slang usage of such terms, know the local meanings of such terms, know the assumed or implied meanings of such terms, be able to remember to always ask plenty of questions to decode what the client wants instead of just assuming, AND have enough resources and foresight to be able to cover when the client walks up to you during a set up and asks "I want X".
> 
> With these terminology discussion, I think it's my own personal goal, and the goal of most of the CB team, to not always insist that one term is right or proper (althought some are certainly more concrete than others) since we can never seem to agree on some terms, but rather, our goal is to widen the base of knowledge concerning terminology and its usage by discussing both intended and proper use, as well as all other usages. Perhaps we can do our part to help foster correct and proper terminology usage, but really, that dream is still a ways away, and till that day, we will all have to know the slang.


-----


NateTheRiddler said:


> Magical! Thanks for the help; guess I’m adding your name to my USITT/LDI “I owe this person a beer” list.


Give mine to @gafftaper or @dvsDave . Or even better, give to Behind-the-Scenes.


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## NateTheRiddler (Feb 15, 2019)

derekleffew said:


> Give mine to @gafftaper or @dvsDave


 I already owe @gafftaper a full case; don't know if I can afford to make it two xD Guess @dvsDave is going to be the lucky recipient!


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## dvsDave (Feb 15, 2019)

NateTheRiddler said:


> I already owe @gafftaper a full case; don't know if I can afford to make it two xD Guess @dvsDave is going to be the lucky recipient!



@gafftaper doesn't drink, just buy him a couple Diet Cokes and he'll be happy. As for me, just spread the word about CB and get as many people as you know to join and I'll be happy.


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## gafftaper (Feb 15, 2019)

Ah for the bad old days before we could afford dimmer per circuit systems and every theater came with a patch bay, you would have never needed to ask. I always taught it this way to my students when I had a patch bay. 

Definitions: 
Channel: The number that the light board identifies for controlling a fixture
Dimmer: The source of power for a fixture
Circuit: The pathway for power to get from a dimmer to a fixture
Channel Number, Dimmer Number, and Circuit Number are not the same thing and are constantly re-patched depending on the needs of a show. 

So: 
-Turning on Channel #1 on the board can turn on any dimmer depending on how you soft patch it in the light board setup. So let's say we want Channel #1 to turn on Dimmer #32 we go into the patch function on the board and set that up. 

-Just because you turned on Dimmer #32 doesn't mean you are sending power to a circuit labeled #32. We use the patch bay to assign a circuit to a dimmer for a source of power. So let's say we want to turn on a fixture plugged into circuit #57. We use the patch bay to connect circuit #57 to Dimmer #32. Depending on the load, the size of the dimmers, and the design of the patch bay, we can often send power to multiple circuits from the same Dimmer. Lets say you have fixtures plugged into Circuits #17 and #123 that you want to turn on and off with #57. If their combined load doesn't exceed the capacity of the dimmer, you can patch all three of them to dimmer #32. So let's say The dimmer is a 2.4k dimmer and we have a 750 watt Source four on each circuit. We can patch all three circuits to the same dimmer. 

When we are done, when we turn on Channel #1 on the board, Dimmer #32 turns on, and the fixtures plugged into circuits #17, #57, and #123 all turn on together. 

Today most theaters have Dimmer Per Circuit systems where a dimmer is hardwired directly to a circuit and there is no possibility of repatching. But older theaters and touring shows still often have patching capabilities. 

@derekleffew it's been a few years since I gave that lecture did I make any mistakes?


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## gafftaper (Feb 15, 2019)

dvsDave said:


> @gafftaper doesn't drink, just buy him a couple Diet Cokes and he'll be happy. As for me, just spread the word about CB and get as many people as you know to join and I'll be happy.


If it's full of fruit, or ice cream and college girls drink it, I might like it.


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## NateTheRiddler (Feb 15, 2019)

gafftaper said:


> Ah for the bad old days before we could afford dimmer per circuit systems and every theater came with a patch bay, you would have never needed to ask. I always taught it this way to my students when I had a patch bay.
> 
> Definitions:
> Channel: The number that the light board identifies for controlling a fixture
> ...





I'm pleased to announce for the first time I actually understood that 100%, thanks to derek's and your explanations. Applause for having that scenario able to ready, aim, fire.


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## BillConnerFASTC (Feb 15, 2019)

derekleffew said:


> Most people will overlook transgressions such as calling a SourceFour a Leko, bulb/lamp, lectern/podium; but those who know will still judge you for it.



You mean those things I call ETC KliegLights are actually Source 4 Lekos? Is it fair to call any LED profile an ERS? (Excluding S4WRDs).


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## gafftaper (Feb 15, 2019)

Does anyone have a picture of an old slider style patch panel? It might be an interesting addition to this story, but I hesitate to try to explain one without a picture.


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## JD (Feb 15, 2019)

When I first got into lighting, 6k dimmers were very popular. It was less expensive to have a few larger dimmers than a lot of smaller ones. The patch panel was standard. You might have five or six circuits going to different locations patched on to one dimmer. Between scenes, there was often a scramble to repatch. The picture I found below is very reminiscent of those days. Each dimmer would have 5 sockets and you would patch your circuits into it. Often, a theater may only have 36 dimmers. By the time I retired, most was "Dimmer per circuit" so the patch panel was a thing of the past. Still, there is a place for this in touring due to the desire to have 6 circuit Socapex connectors on the rack, and the need to assign them to common 2k dimmers. So, what's old is new again! ... for now.


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## gafftapegreenia (Feb 15, 2019)

I don’t have a picture of the Electro-Controls slider patch still in use in the TV studio at my alma matter, but I do have this 1966 Century install I’m working with this month.


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## derekleffew (Feb 15, 2019)

gafftaper said:


> Does anyone have a picture of an old slider style patch panel? It might be an interesting addition to this story, but I hesitate to try to explain one without a picture.


https://www.controlbooth.com/threads/just-for-curiosity-and-discussion.32306/#post-284683


https://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/ECpatchbay.JPG/220px-ECpatchbay.JPG

Since both slider and telephone patch panels are obsolete (but pin patch is not) I hesitate to throw too much at Nate at one time (or ever). All yall's doing now is showing your age.
-----

gafftaper said:


> @derekleffew it's been a few years since I gave that lecture did I make any mistakes?


Everything sounds correct, but I again question why even bring it up. Odds are Nate is either going to be working with a DPC installation where dimmer and circuit can be used interchangeably, or with all portable dimmer rack s / dimmer pack s.


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## RonHebbard (Feb 15, 2019)

derekleffew said:


> Socket. The base is part of the lamp.
> Spend as much time as possible in the wiki.
> Most people will overlook transgressions such as calling a SourceFour a Leko, bulb/lamp, lectern/podium; but those who know will still judge you for it.
> 
> ...


 *@derekleffew* What about posters who type Viola when they likely intended to type Voila? (Sp?) [Or Rouge Vs. Rogue] 
Toodleoo! 
Ron Hebbard


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## gafftaper (Feb 15, 2019)

@derekleffew there are still a few community theaters out there with patch panels. Not a lot, but some. I have always liked teaching the concept because it helps to understand the possibilities and joy of repatching your console, it also helps to teach good discipline with loads for circuits, and it prepares you to deal with a touring patch panel. 

So, @NateTheRiddler see that picture Derek posted. It's a series of sliders that lock into notches as you slide up and down. Each notch represents a dimmer Each slider is a circuit. So you had to watch your load math and make sure you didn't assign too many circuits to the same dimmer notch and blow a breaker. It was pretty cool but at some point in the 80's probably the cost of dimmers came down enough that it made more sense to just go dimmer per circuit.


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## JohnD (Feb 15, 2019)

Then there were the Kliegl patch options:
ROTOLECTOR
Then there was the SafePatch telephone exchange style unit. Unlike the Century one shown above the Kliegl had either a toggle switch or perhaps a circuit breaker mounted below or beside each hole. If you were unpatching a circuit when you pulled out the plug it tripped the switch off. When patching you inserted the plug and flipped the switch back on(it could be done one handed).
SAFEPATCH


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## danTt (Feb 15, 2019)

derekleffew said:


> Also, the CEM is the removable module that is the rack's brain. It doesn't have a patch bay. The dimmer rack has a patch bay, one CEM (and often an additional spare in a dummy slot), and dimmer modules (also sometimes spares in dummy slots).
> 
> That's it! Viola.



Of course, it's possible to add an additional layer of patch/translation at the cem level, but 95% of the time it's pure evil To do so.


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## cbrandt (Feb 19, 2019)

I know that we're seeing them phased out in the installation market, but I still have 8x 48 channel dimmer racks in my rental inventory with full patch panels that see regular use. They won't go out of style in the temporary market until we've shifted completely out of dimmers, or made the downgrade to dimmers at the fixtures.

I'd argue they're still a pretty important thing to know about, even if you don't totally understand how they work.


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## STEVETERRY (Feb 19, 2019)

derekleffew said:


> See here: https://www.controlbooth.com/threads/etc-sensor-patch-bay-touring-rack.40366/ .
> 
> At the fixture, a light is plugged into one of six circuits on the multi-cable break-out. Let's say the second circuit.
> The break-out is then plugged into a Socapex-style multi-cable that happens to be labeled [R1]A.
> ...



Good explanation. But some may also look for an answer to WHY a touring rack with 20A branch circuits and 20A dimmers needs a patch panel? After all, permanent installation patch panels were used to connect small numbers of BIG dimmers (3.6kW to 12kW) to larger numbers of 20A branch circuits. In a high density 2.4kW touring rack, why not simply hard wire the Socapex circuits to dimmer outputs in a dimmer-per-circuit arrangement? 

As the guy who designed and built the first 96-channel digital touring dimmer rack in the industry at Production Arts in 1983, I can offer an explanation to this:

1. A touring rack without a patch panel is wasteful of both circuits and dimmers. The original high-density touring rack had sixteen 12-circuit multicable outlets. If you sent a multi to a location that needed less than 12 circuits (say a box boom), without a patch panel you would be forced to use up 12 dimmers. The same holds true, to a lesser degree, with 6-circuit multicables.

2. A patch panel was needed to twofer circuits at different locations, which was common in many hookups.

BTW, that patch panel topology and output circuit count persists today in modern touring racks, so I guess it might have been on the right track. 

But, as I'm fond of saying, in ten years we may struggle to remember what a dimmer was. 

There you have it.

ST


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## theatricalmatt (Feb 19, 2019)

Another use for patch panels is balancing loads across all three phases, as well as reassigning individual circuits to hot patches or relay cards as needed out on electrics.


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## epimetheus (Feb 19, 2019)

JohnD said:


> Then there were the Kliegl patch options:
> ROTOLECTOR
> Then there was the SafePatch telephone exchange style unit. Unlike the Century one shown above the Kliegl had either a toggle switch or perhaps a circuit breaker mounted below or beside each hole. If you were unpatching a circuit when you pulled out the plug it tripped the switch off. When patching you inserted the plug and flipped the switch back on(it could be done one handed).
> SAFEPATCH



Rudder Auditorium at Texas A&M University had a Kliegl patch panel very similar to the SAFEPATCH, just without the circuit breakers. It was fed by (60) 10k? dimmers and had 400+ circuits. Each dimmer had 10 holes and all the circuit hots were above with counter-weighted, retracting leads. It was an impressive site and fun to patch and re-patch for shows. It was still in service when I graduated in 2005, but now their tech spec packet indicates (6) 96 ckt Sensor racks.


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## SteveB (Feb 20, 2019)

STEVETERRY said:


> Good explanation. But some may also look for an answer to WHY a touring rack with 20A branch circuits and 20A dimmers needs a patch panel?
> 
> But, as I'm fond of saying, in ten years we may struggle to remember what a dimmer was.
> 
> ...



Great write up Steve, made me recall and not so fondly, that 12 circuit multi.....

And for those occasions and on a house patch panel, when there was excess capacity on the dimmer and you had 1 too many patch cords to plug in, we had these. I've posted this before and there were a few who questioned the code compliance of this.


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## derekleffew (Feb 20, 2019)

SteveB said:


> made me recall and not so fondly, that 12 circuit multi...


I've never met anyone who remembers 12/37 Pyle-National cable "fondly."


SteveB said:


> And for those occasions and on a house patch panel, when there was excess capacity on the dimmer and you had 1 too many patch cords to plug in, we had these.


Rumor has it "patch panel two-fers" exist for Sensor touring racks also. As well as long extensions to jump from one rack to another. Since 1992, I've never seen either in use.


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## RonHebbard (Feb 20, 2019)

derekleffew said:


> I've never met anyone who remembers 12/37 Pyle-National cable "fondly."
> 
> Rumor has it "patch panel two-fers" exist for Sensor touring racks also. As well as long extensions to jump from one rack to another. *Since 1992, I've never seen either in use.*


 *@derekleffew* and *@SteveB* In the 1970's we had 6Kw / 50 Amp patch panel quad boxes housing four 100 Amp females with each box fed by approximately 6' of 6 gauge copper cable sourced by a 100 Amp patch panel male connector. in 1973 when the venue opened, we borrowed several of these quad boxes from Toronto's O'Keefe Centre. By approximately 1975 we punched additional holes in the vertical face of our patch panel and added 18 four-way and five-way patch panel plugging boxes within our patch panel each with counter-weighted 6 gauge copper tails and 100 Amp male patch panel connectors. 
*Pyle National 12 / 37 12 circuit 20 Amp cables and connectors*. When I left my theatre gig and played head electrician in an automation and scenery shop for a few years beginning in 1991, the first major project we built was a flown incandescent and neon sign for "Best Little Whorehouse Goes Public"; directed by Tommy Tune with lighting design by Jules Fischer and Ms. Peggy Eisenauer; the sign was fed by six Pyle National's from one side plus five more Pyle Nationals from the other side and one Socapex for a total of 138 twenty Amp circuits including two spares; one spare in one of the Pyle Nationals and the remaining spare in the lone Socapex. I've posted of this sign in greater detail here on the Control Booth forum before, possibly twice. 
Toodleoo! 
Ron Hebbard


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## eadler (Feb 20, 2019)

JohnD said:


> Then there were the Kliegl patch options:
> ROTOLECTOR


That one linked is still sitting in the same studio (although disconnected now) as of a week or so ago.


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## SteveB (Feb 20, 2019)

RonHebbard said:


> *@derekleffew* and *@SteveB* In the 1970's we had 6Kw / 50 Amp patch panel quad boxes housing four 100 Amp females with each box fed by approximately 6' of 6 gauge copper cable sourced by a 100 Amp patch panel male connector. in 1973 when the venue opened, we borrowed several of these quad boxes from Toronto's O'Keefe Centre. By approximately 1975 we punched additional holes in the vertical face of our patch panel and added 18 four-way and five-way patch panel plugging boxes within our patch panel each with counter-weighted 6 gauge copper tails and 100 Amp male patch panel connectors.
> *Pyle National 12 / 37 12 circuit 20 Amp cables and connectors*. When I left my theatre gig and played head electrician in an automation and scenery shop for a few years beginning in 1991, the first major project we built was a flown incandescent and neon sign for "Best Little Whorehouse Goes Public"; directed by Tommy Tune with lighting design by Jules Fischer and Ms. Peggy Eisenauer; the sign was fed by six Pyle National's from one side plus five more Pyle Nationals from the other side and one Socapex for a total of 138 twenty Amp circuits including two spares; one spare in one of the Pyle Nationals and the remaining spare in the lone Socapex. I've posted of this sign in greater detail here on the Control Booth forum before, possibly twice.
> Toodleoo!
> Ron Hebbard



Patch panel quad boxes. That’s not something I ever want to see. I thought my two-fers were bad enough.


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## RonHebbard (Feb 20, 2019)

SteveB said:


> Patch panel quad boxes. That’s not something I ever want to see. I thought my two-fers were bad enough.


 *@SteveB* The original telco-style patch was custom built by Strand Century in their Toronto, Ontario shop. All of the female receptacles were rated for 100 Amps / 12 Kw. All of the male connectors were rated for 100 Amps / 12 Kw. All one hundred of the dimmers were 6 kw each. Unfortunately each of the six non dims were only rated at 20 Amps. Originally there were 307 20 Amp load tails each protected by a 20 Amp Heinemann magnetic breaker and 17 50 Amp load tails each protected by a 50 Amp magnetic breaker. The panel was approximately 7.5 feet wide with the pairs of female receptacles repeating three times across the width of the panel thus there were six receptacles per 6 Kw dimmer with two near the left end, two more near the center and the last two towards the right hand end thus if you wanted to patch six FOH load circutis into one 6 Kw dimmer you could make two reach for sure and possibly two more may reach the center two females but there was no way your last two FOH load tails would reach all the way across to the last two receptacles near the right hand end. This was why we needed the quad boxes to manage to plug six tails into a six Kw. dimmer. Lamps were typically 750T12's and 1MT12 1 Kw's so plugging six per 6 Kw dimmer was never a problem with the 750 Watt lamps. I suspect I've more than beaten this to death.
Toodleoo!
Ron Hebbard


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## SteveB (Feb 20, 2019)

RonHebbard said:


> *@SteveB* I suspect I've more than beaten this to death.
> Toodleoo!
> Ron Hebbard



Nicest patch panel design I ever saw was the Kliegl systems that had the male patch connectors on an overhang with all the cabling on weights. You pulled down and plugged direct to the dimmer receptacle. Santa Fe Opera had this prior to the '99 renovation.


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## epimetheus (Feb 21, 2019)

SteveB said:


> Nicest patch panel design I ever saw was the Kliegl systems that had the male patch connectors on an overhang with all the cabling on weights. You pulled down and plugged direct to the dimmer receptacle. Santa Fe Opera had this prior to the '99 renovation.



This is what Rudder Auditorium at Texas A&M had as well. Now the smaller Rudder Theater had a wonderful slide patch...


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## JonCarter (Feb 21, 2019)

After watching almost a week's worth of patch systems descriptions I decided it's time to throw this one into the mix.

In the early '60s I worked as chief elec. in a small theatre in Cleveland. The plant was built in the late '40s and apparently was designed (or at least assisted by) a very good theatre designer. About three hundred capacity, 30 foot prosc., 40' to back wall, 20' off both SL & SR, (sorry, no orch. pit :-( ), TWO very nice ceiling coves the full width of the house, nice hidden prosc. splay positions, grid over twice prosc. height. The board was in a projection booth with good stage visual; 48, 6 kW autotransformers plus some for the house. The board and cross-connect were built by Cleveland Switchboard Co., a local manufacturer who we used many times to build oddball stuff for various projects.

Now, to the patch panel. On the back wall of the booth was a cabinet about 8' high x 6' wide and a foot deep. In the cabinet was a slate back board with 48, 6' vertical copper buss bars, each about 1" x 1/8", one for each dimmer circuit, with a 60A cartridge fuse at the top of the cabinet for each bar. The bars were mounted perpendicular to the back board with the 1/8" edge facing edge out. Mounted above (away from the back board) in front of these vertical bars were horizontal bus bars for each circuit (I don't remember how many; this has been a few weeks ago but they filled the 7' cabinet), also 1" x 1/8" with the1/8" edge facing out. Each horizontal bar had a 30A cartridge fuse for its circuit at the side of the cabinet. On each horizontal bar was a plug (for want of a better word) which could be moved side-to-side when pulled "out" away from the back board without touching the vertical bars below. The plug for any circuit could be pushed "in" to make contact with the vertical bus bar for any dimmer. 

This cross-connect allowed any circuit to be connected to any dimmer. Of course,this operating cross-connect this required a bit of intelligence (read: a _NON-IDIOT_) on the part of the electrician. One _COULD_ plug everything in the theatre to _ONE _dimmer, but this would be kinda stupid and would instantly blow the dimmer's fuse. One _COULD _plug, kill and re-plug hings "hot", but this also would be kinda stupid and hard on the buss bars. One_ COULD_ lean up against the cross-connect and get a big surprise, but this also would be kinda stupid. One _COULD_ reach into the cross connect and grab things while hot, -- but then, well, you know. 

I never had any trouble plugging shows per the designer's wishes, sometimes re-plugging things pretty quickly between dim-outs & dim-ins) (Thanks, Paul Marantz!) and never heard of anyone getting zapped on this equipment. Oh, and this was long before OSHA and everything else that interferes with our lives.


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## NateTheRiddler (Feb 25, 2019)

Hey, I just want to throw out a huge thanks/appreciation to all of the industry veterans who’ve taken time to comment on the history of the patch panel and similar technologies, here.

The textbooks I’m studying as I try to rebuild my foundation in lighting don’t even scrape the surface on the evolution of the technology over the years, and I imagine a certain level of appreciation for that evolution is lost with modernization and ignorance.

I can’t thank you all enough for giving me a solid hour of reading material, and enough reference to spend another week just googling history.

I hope you don’t _all _expect to land on my USITT “IOU Beer” tab though; I don’t think I can afford all that booze. Will internet high fives suffice?


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## JonCarter (Feb 25, 2019)

@NateTheRiddler You're welcome. Glad to be able to help a "newbie" with what's now ancient history. On the subject of cross-connects you might also be interested the description of another in this thread https://www.controlbooth.com/threads/triangular-stage-plug.44116/#post-383893


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## dvsDave (Feb 27, 2019)

@RonHebbard asked me to post this picture in this thread for him. 




RonHebbard said:


> The photo is of a slide patch currently still in use in Hamilton, Ontario, Canada. Odd numbered load breakers are across the top and even numbered load breakers are across the bottom. It was originally installed in a secondary school theatre in 1970 and relocated to a community theatre approximately 20 years ago when a larger slide patch was installed in the secondary school.
> 
> Toodleoo!
> Ron Hebbard


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## RonHebbard (Feb 27, 2019)

dvsDave said:


> @RonHebbard asked me to post this picture in this thread for him. View attachment 17604


 *@NateTheRiddler* When the slide patch was originally installed in 1970 it distributed 42 Six Kw dimmers and six non-dims to approximately 98 or 100 twenty amp old style twist locks. In its current use I believe it's distributing 36 2.4 Kw CD80 Pack dimmers plus 6 non-dims; one or two of the non-dims power a smaller DMX shoe-box dimmer typically utilized to dim practicals. 
Thanks *@dvsDave* for posting this photo. 
Toodleoo! 
Ron Hebbard


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## Dionysus (Feb 28, 2019)

dvsDave said:


> @RonHebbard asked me to post this picture in this thread for him. View attachment 17604


Awesome thanks Dave and Ron!

I remember when I started at the Grand the McManus had a slide patch... However, some people in the past obviously did some patching live and/or other improper operation causing it to stop working correctly. Was ripped out and dimmer rack replaced when the Strand a21 architectural panels were installed. Wish I had taken photos back in the day!


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## SteveB (Feb 28, 2019)

dvsDave said:


> @RonHebbard asked me to post this picture in this thread for him.View attachment 17604



I find it remarkable that it was found to be cost effective to re-locate this in 1999 or there-abouts. The labor to remove and re-install boggles the mind. This is likely a good 15 years AFTER dimmer-per-circuit systems were the cost effective system. 

But when you say "community theater" the image that comes to mind is somebody's Dad/Husband/day-job-is-an-electrician donating some time.


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## RonHebbard (Feb 28, 2019)

SteveB said:


> I find it remarkable that it was found to be cost effective to re-locate this in 1999 or there-abouts. The labor to remove and re-install boggles the mind. This is likely a good 15 years AFTER dimmer-per-circuit systems were the cost effective system.
> 
> But when you say "community theater" the image that comes to mind is somebody's Dad/Husband/day-job-is-an-electrician donating some time.


 *@SteveB* You're conjuring the right image: The three Strand CD80 twelve by 2.4 Kw packs are in the basement in a locked room off the prop room to isolate their fan noise. 1.25" EMT brings the dimmer outputs straight up the wall to the bottom of the slide-patch and the approximately 100 circuits are distributed around the theatre / auditorium as several Socapex's and primarily 2P&G's as tails off of troughs. Fixtures are a totally mixed bag from ancient ellpsoidals still running a very few 500T14bi-posts to Strand 2200 series, Altman 65's and their predecessors, plus Strand grey ellipsoidals that pre-dated the 2200 series to Source Four 36 and 50 degrees. Add a pair of I-Mirrors and stir to suit. The community theatre has been in operation since sometime prior to 1900 with only a minor interruption for the first world war. The person largely responsible for keeping everything maintained and operational is retired from his career as a sales support technologist with Reliance Electric specializing in LARGE AC and DC motors and drives globally; think steel mills, pipe lines and ocean port gantry crane control systems and their drives. 
Toodleoo!
Ron Hebbard


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## SteveB (Feb 28, 2019)

RonHebbard said:


> *@SteveB* You're conjuring the right image: The three Strand CD80 twelve by 2.4 Kw packs are in the basement in a locked room off the prop room to isolate their fan noise. 1.25" EMT brings the dimmer outputs straight up the wall to the bottom of the slide-patch and the approximately 100 circuits are distributed around the theatre / auditorium as several Socapex's and primarily 2P&G's as tails off of troughs. Fixtures are a totally mixed bag from ancient ellpsoidals still running a very few 500T14bi-posts to Strand 2200 series, Altman 65's and their predecessors, plus Strand grey ellipsoidals that pre-dated the 2200 series to Source Four 36 and 50 degrees. Add a pair of I-Mirrors and stir to suit. The community theatre has been in operation since sometime prior to 1900 with only a minor interruption for the first world. The person largely responsible for keeping everything maintained and operational is retired from his career as a sales support technologist with Reliance Electric specializing in LARGE AC and DC motors and drives globally; think steel mills, pipe lines and ocean port gantry crane control systems and their drives.
> Toodleoo!
> Ron Hebbard



I think the grey Century Lekos were the 1500 series. Strand Century had a nifty upgrade to these where you purchased the 2200 series rear end and repurposed the lens tube. We did that for over 100 units, gave us a nice modern 1KW rated unit.


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## RonHebbard (Feb 28, 2019)

SteveB said:


> I think the grey Century Lekos were the 1500 series. Strand Century had a nifty upgrade to these where you purchased the 2200 series rear end and re-purposed the lens tube. We did that for over 100 units, gave us a nice modern 1KW rated unit.


* @SteveB* "A nice modern 1KW _rated_ unit" whose 6x9 rear lenses cracked regularly with FEL's and 4.5 x 6.5's had to be lamped down to 750 Watts once Strand got fed up with shipping gratis lenses under warranty.
Thanks for the memories *@SteveB*
Toodleoo!
Ron Hebbard


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## dvsDave (Mar 25, 2019)

Uploaded on behalf of @RonHebbard 


> Please find a few photos of an appreciably larger slide patch still in service until purportedly the end of June this year, 2019 when the entire secondary school is slated for demolition. This patch was originally installed in neighboring Oakville, Ontario’s PAC decades ago and was removed from service when they upgraded to dimmer per circuit. At that point the smaller slide patch I previously submitted was removed from a secondary school in downtown Hamilton, Ontario and relocated to an amateur group’s rehearsal and performance space where it’s currently still well maintained and in regular service. This larger slide patch was moved from Oakville and installed in the secondary school theatre in the heart of downtown Hamilton. When it was reinstalled in the secondary school the Heinemann 60 Amp magnetically actuated breakers protecting the circuits with the red sliders were replaced with 20 Amp magnetically actuated Heinemann breakers to properly protect the additional circuit wiring and old style 20 Amp twist-lock connectors in the secondary school’s theatre. In mere months it’s slated to hit the dumpster.
> 
> *If any CB’ers are in need of parts for this larger panel it MAY be possible to impose upon a few friends to save a few from the wrecking ball.*


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## FMEng (Mar 25, 2019)

That is an Ariel Davis, or its successor. I could be wrong on my history, but I think AD became Electro Controls.


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## GwynEaves (Nov 13, 2019)

Hi...this equipment is clearly not a portable appliance! PAT testing such an item is foolish to say the least, it is electrical distribution equipment, and it takes a significant level of power input, probably at least 50kW! PAT testing is aimed at power using equipment, at the end of a circuit where earth continuity may be suspect, and leakage should be controlled.


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## DuckJordan (Nov 14, 2019)

GwynEaves said:


> Hi...this equipment is clearly not a portable appliance! PAT testing such an item is foolish to say the least, it is electrical distribution equipment, and it takes a significant level of power input, probably at least 50kW! PAT testing is aimed at power using equipment, at the end of a circuit where earth continuity may be suspect, and leakage should be controlled.


I'm not entirely sure who you are responding to. The origional thread was about a touring Dimmer rack and these photos are showing installed alternatives to what we see today.


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## TimMc (Nov 17, 2019)

GwynEaves said:


> Hi...this equipment is clearly not a portable appliance! PAT testing such an item is foolish to say the least, it is electrical distribution equipment, and it takes a significant level of power input, probably at least 50kW! PAT testing is aimed at power using equipment, at the end of a circuit where earth continuity may be suspect, and leakage should be controlled.


PAT is not required anywhere in the USA.

For those unacquainted, PAT is "portable appliance testing" done annually in the UK (and maybe elsewhere) that is intended to find electrical problems with portable equipment used by personnel. The "applicance" either passes, or fails and is repaired or removed from service.


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## Cue_547 (Apr 21, 2021)

dvsDave said:


> @RonHebbard asked me to post this picture in this thread for him. View attachment 17604


So this just solved for me, what the port in the middle of an old Major lightboard was...a sliding patch bay. That was the very first lightboard I'd ever seen in my life way back in 6th grade. I have no idea what model it was. Consequently, that was the first lightboard I'd ever ran and the beginning of my interest/love of stage lighting.


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## RonaldBeal (Apr 22, 2021)

Story time:
Back in the late 1900's I worked for a community theater in Georgia that had 2 Kliegpac 9 dimmer packs (each pack had 9 x 20 amp dimmers,) with one non functional dimmer on each pack, so we had a grand total of 16 working dimmers.
And 350 circuits.
My job for "My Fair Lady" was patchman. 
Would re-patch after practically every cue. (fortunately there only about 80 or so cues in the show, and we only used about 100 ish circuits)
First tech rehearsal I discovered that the color coded labels I had spent hours making don't work under a red worklight! Many colors looked the same!
(ended up with a dimmed littlelite gooseneck so I could see colors again)


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