# Dimmer rack output panel



## derekleffew (Aug 16, 2010)

This is an old dimmer rack I've recently encountered. How many dimmers does the rack have? What is the capacity of each dimmer? What is the purpose of the red switches?



Who made the rack and when (approximately)?​


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## DuckJordan (Aug 16, 2010)

it has 6 dimmers, capacity is (i'm guessing here) 15A at 120V, and the red switches are for turning off specific receptacles so if you have more stuff plugged in you don't have more lights than what you wanted on.

As far as make and year, NO idea


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## epimetheus (Aug 16, 2010)

As DuckJordan said, it's a 6 dimmer panel.

Capacity, however, is likely higher than 15A *per dimmer*. Each dimmer has 4 stage pin (2P+G if you prefer).

The red switches are actually circuit breaker handles for each receptacle I'd guess. Circuit breaker rating can't be seen (as far as I can tell), but those stage pin receptacles are rated for 20A, so I'd guess 20A circuit breakers.

For dimmer capacity, I'd guess somewhere between 6k and 10k, but it's impossible to be specific without more info.

Make and year - no clue.

Edit: My 6 dimmer conclusion is purely based on the tape numbers. I suppose they could refer to something other than dimmer numbers, in which case my answer would be different.


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## headcrab (Aug 16, 2010)

I am going to say it has 24 channels. Having multiple output connectors, each with its own breaker, for a single physical dimmer channel, makes no sense to me. If you wanted more than one light on a channel, you would use a two-fer. If you wanted multiple channels dimming together, patch them together.
The red switches look like thermal circuit breakers. They are overcurrent circuit protection devices.
I agree with the 2.4K (120VAC) output.
Manufacturer and year, no clue, except that it looks like an old analog dimmer I found last summer, which was made by Applied Electronics, probably in the 1980's.


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## epimetheus (Aug 16, 2010)

headcrab said:


> I am going to say it has 24 channels. Having multiple output connectors, each with its own breaker, for a single physical dimmer channel, makes no sense to me. If you wanted more than one light on a channel, you would use a two-fer. If you wanted multiple channels dimming together, patch them together.



What if the dimmers have more than 2.4k capacity? You have to protect the 20A connector and subsequent cable. When I was in college, the main stage had (60) 12k dimmers with an old Kliegl patch panel. Each dimmer had 10 single-pole sockets. You would pull the retractable lead (the hot lead for the circuit to be patched) from the overhead panel and patch it to the appropriate dimmer. Each overhead lead had it's own circuit breaker. Each dimmer could have 10 circuits patched to it.


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## jstandfast (Aug 16, 2010)

Almost certainly a higher capacity dimmer, hence the breaker on each 20 amp output 
connector. If memory serves, it was in the late seventies/early eighties, when big dimmers went portable
that manufactures began paying attention to this. Another common config was to have one 60 amp connector and four 20 amps on each dimmerr. If you want to know who made it show us some other views......


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## jstandfast (Aug 16, 2010)

My apologies to all. Didn't notice that this was a "Question of the Day". I'll butt out now (or at least until next week).


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## cdcarter (Aug 23, 2010)

My honest guess has already been thrown out, and those red switches certainly look like circuit breakers, but I'd like to throw out the possibility they are also three-way "patching" switches like on a Junior 8. Thrown up, the circuit is full on, on the middle pole the circuit is on the dimmer, and thrown down the circuit is off.


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## STEVETERRY (Aug 23, 2010)

The red breaker handles might be an important clue.

ST


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## STEVETERRY (Aug 23, 2010)

headcrab said:


> I am going to say it has 24 channels. Having multiple output connectors, each with its own breaker, for a single physical dimmer channel, makes no sense to me. If you wanted more than one light on a channel, you would use a two-fer.


 
How about if it were a large dimmer (3600W or 6000W), but you wanted it to feed only 20A (2400W) circuits?

ST


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## STEVETERRY (Aug 23, 2010)

headcrab said:


> The red switches look like thermal circuit breakers.


 
No-fully magnetic circuit breakers by Airpax or Carling.


ST


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## bdkdesigns (Aug 24, 2010)

To me, it looks like 12 30A circuits. I had something similar looking to that style rack in a light lab in grad school so that is what I am basing it off of. But there does appear to be a clusters of two 20A Stagepin receptacles, with a small gap, and another cluster. I can't zoom in enough on this old computer monitor to see the breakers but if that is correct, and Steve's comment leads me to believe that I'm on the right track, those are meant to ensure that you don't go over the 20A on each connector. Even though the entire dimmer is rated for 30A, each plug is only 20A so it is sort of a built in safety check.


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## derekleffew (Aug 24, 2010)

What are the ~1.5"x1.5" square bumps under the gaffers tape? Why is "51 C" ON (or off, depending on how it's mounted)?

C'mon, show us the other side!


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## jstandfast (Aug 24, 2010)

derekleffew said:


> What are the ~1.5"x1.5" square bumps under the gaffers tape? Why is "51 C" ON (or off, depending on how it's mounted)?
> 
> C'mon, show us the other side!


 
My personal bet is those squares would be the manufacturers " Rack # " as opposed to the "system # " shown us in the ever popular
black gaffers tape........


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## epimetheus (Aug 24, 2010)

Could they be single Edison outlets for testing the circuit at the rack with a clip light or the like? Possibly taped off because they're not connected any more due to rack modifications.

Getting a little anxious for an explanation here...

Sent from my Incredible using Tapatalk.


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## starksk (Aug 24, 2010)

derekleffew said:


> C'mon, show us the other side!



Not to poke the bear too much here, but _you_ are the OP.

~Kirk


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## derekleffew (Aug 24, 2010)

starksk said:


> Not to poke the bear too much here, but _you_ are the OP.


I wondered how long and who would be the first to catch that. I posted the original picture for a member who wishes to remain anonymous.


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## Footer (Aug 24, 2010)

Its *was* my rack. It was what was connected to the connector that was the QOTD several months ago... 

The dimmers in the rack were long since gone way before I took the job at this theatre. All that was left was a sad buss bar, the front panel, and a cinch jones connector. The rack were hauled off for scrap several months ago...


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## STEVETERRY (Aug 29, 2010)

.125" thick gravoply engraved labels.

ST


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## derekleffew (Sep 9, 2010)

derekleffew said:


> How many dimmers does the rack have?


6.


derekleffew said:


> What is the capacity of each dimmer?


6000W. We would have no way of knowing that if Footer hadn't told us. It is safe to assume that it's larger than 2.4kW and 3.6Kw, and less than 10K.


derekleffew said:


> What is the purpose of the red switches?


As said above, the red switches are OPD s to protect wiring attached to the 20A-2P&G receptacle s.


derekleffew said:


> Who made the rack and when (approximately)?


Mr. Terry will likely know conclusively, but I'm betting: Lighting Methods Inc., circa 1982.


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## mstaylor (Sep 10, 2010)

It could likely be a TTI. It seems to me the TTI's physically ran larger than the LMI's.


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## jstandfast (Sep 10, 2010)

mstaylor said:


> It could likely be a TTI. It seems to me the TTI's physically ran larger than the LMI's.


 
My bet would be LMI. The TTI product (7.2s if memory serves ) was a much more
rectangular affair,and blue to boot. And it looks like an LMI frame.


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## STEVETERRY (Sep 10, 2010)

derekleffew said:


> 6.
> 
> Mr. Terry will likely know conclusively, but I'm betting: Lighting Methods Inc., circa 1982.


 
That would be my exact guess.

ST


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## mstaylor (Sep 12, 2010)

I did a show yesterday that used all LMI racks and an old Avolite board, all analog. It was fun to do an old school show, they had zero DMX toys.


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