Power Distros

[rochem]

Hello all,

I have a few questions about Power Distros that I've been wondering about for a while now. This isn't for any specific application, just my own curiosity and personal knowledge gain. Also, I understand that for most of this, there are a thousand legal and safe ways to do it, but I'm specifically wondering what the most common ways of doing things are, whether or not they are the most logical. I have a thorough understanding of the concepts behind 3-phase and 208V power and such, but I don't know how it's actually traditionally applied in a theatre setting.

So lets say you're building a medium-to-large sized touring package that will tour the US for a musical, with many moving lights and conventionals in the rig. For the conventionals, most of the time, you would reach for a few ETC Sensor+ 96 x 2.4kW Touring Racks with Socapex outputs. That seems to be fairly standard, at least from, what I've seen. My question is about what you do when you get into Non-Dimmed power for moving lights and other elements of the production, such as motor power. Assuming you had a rig of entirely 120V moving lights, you could theoretically populate your Sensor racks with enough Relay modules and just run everything through the dimmer racks. With a large rental package, is it fairly common to change out dimmer modules as needed for your production, or do you generally just take full racks from the rental house without any shuffling of modules? This question also applies to scroller power and other remotely controlled straight power devices, as well as to console power and other constant powered devices which aren't traditionally part of the actual lighting rig.

Now, lets assume that you have a number of fixtures that do require 208V power. How would you go about powering these? As far as I'm aware, there's no single manufacturer that everyone goes to, like ETC for dimmer racks. I also can't seem to find anything about "standard" sizes for power distros, the way that most dimmer racks come in standard sizes (96, 48, etc.). Are there standard sizes (other than multiples of three, of course), or are most distros custom built as needed for each production? Also, how would you go about mixing 208V power with 120V power? Would your ETC dimmers generally handle all non-dim 120V power (via modules) while the distro took care of 208V, or would you mix the two voltages in the same distro?

Now, assuming that you've procured the correct distro for the show, how do you spec power going to each fixture? Again, I'm speaking mostly to how things are normally done, not the minimum requirements to be in compliance with code. Can you use the same 6-circuit socapex cables that you use with 120V power, or something similar to them? Or do you generally use individual cables headed to each position? Also, I've often seen L6-20 connectors used on 208V lines, presumably to prevent accidentally plugging into the wrong voltage. Is this fairly standard, or is there another connector that's often seen?

And finally, once you get to the theatre, how do you go about tying everything in to a company switch? My assumption is that you'd usually go from the company switch into a distro, then from that into your dimmer racks, but I could easily be wrong. Also, are there other parts of a lighting rig that would receive direct 3 phase power from the company switch before being pushed through a dimmer rack or distro? I'd assume all power for the show would come from these two pieces, but I could be wrong.

Sorry for the long post. Thanks in advance!

[derekleffew]

I'll answer one of your questions, and leave the rest for others.

...I also can't seem to find anything about "standard" sizes for power distros, the way that most dimmer racks come in standard sizes (96, 48, etc.). Are there standard sizes (other than multiples of three, of course), or are most distros custom built as needed for each production? ...

For 208V ML PD, spend some time at Motion Labs site. The most common sizes are 200A (24-way) and 400A (48-way). These use the same type of Socapex-compatible multi-cable as dimmer racks, but with L6-20 break-out s.

[soundman]

With a large rental package, is it fairly common to change out dimmer modules as needed for your production, or do you generally just take full racks from the rental house without any shuffling of modules? This question also applies to scroller power and other remotely controlled straight power devices, as well as to console power and other constant powered devices which aren't traditionally part of the actual lighting rig.

I have never seen anyone change out a module. If a dimmer rack is used I have always seen it full of dimming modules. There are other more efficient ways of distributing 120V than using relay modules. Once and a while the constant power outputs might be tied into work lights. For things like scroller and console power you would tie into a power distro rack.

Now, lets assume that you have a number of fixtures that do require 208V power. How would you go about powering these? As far as I'm aware, there's no single manufacturer that everyone goes to, like ETC for dimmer racks. I also can't seem to find anything about "standard" sizes for power distros, the way that most dimmer racks come in standard sizes (96, 48, etc.). Are there standard sizes (other than multiples of three, of course), or are most distros custom built as needed for each production? Also, how would you go about mixing 208V power with 120V power? Would your ETC dimmers generally handle all non-dim 120V power (via modules) while the distro took care of 208V, or would you mix the two voltages in the same distro?

You are correct that there is no standard but Motion Labs makes some pretty nice ones, although I don't think they make one with breakers in front connectors and cams in rear stock. It depends on what the shop has in stock and who's gear they own. Most racks are 'as is' save PRG series 400 system. Unless you are on a big tour that can throw your weight around you get what they got. If you want a rack with 4 L 21-30 out puts, cam through and 12 channels of edison outs 12 channels of 120V and 24 channels of 208 you might get two racks even though all that could fit in one.

Now, assuming that you've procured the correct distro for the show, how do you spec power going to each fixture? Again, I'm speaking mostly to how things are normally done, not the minimum requirements to be in compliance with code. Can you use the same 6-circuit socapex cables that you use with 120V power, or something similar to them? Or do you generally use individual cables headed to each position? Also, I've often seen L6-20 connectors used on 208V lines, presumably to prevent accidentally plugging into the wrong voltage. Is this fairly standard, or is there another connector that's often seen?

You use the same 6 circuit cable, you just label it VERY WELL, at least one lighting company in the USA has come up with a way to wire there 208V break-ins/outs so that if you plug a 120V connector breakout into a 208V the gear will see no voltage. Most people just label it well.

And finally, once you get to the theatre, how do you go about tying everything in to a company switch? My assumption is that you'd usually go from the company switch into a distro, then from that into your dimmer racks, but I could easily be wrong. Also, are there other parts of a lighting rig that would receive direct 3 phase power from the company switch before being pushed through a dimmer rack or distro? I'd assume all power for the show would come from these two pieces, but I could be wrong.

Most of the time it will go switch>feeder>AC rack or dimmers>AC rack 2 or dimmers 2> and so on. Most of the time people will use Ts or the through on the rack to daisy chain racks together until they hit the limit on the feeder or run out of gear. Sometimes rigging will be put on its own switch so lighting can be struck with out powering down rigging.

[len]

Many people make distros, and most are semi-custom, so the "standard" doesn't really exist like with dimming. You can buy/rent them with both voltages, but I don't think it's possible to deliver both 120 and 208 in the same socapex. Most distros have socapex connections, with some service outlets (typically 120v edison) and the soca then are run up to breakouts. 120v are almost always edison connections and the 208v are usually some sort of twist-lock so they can't be confused. Also, a touring rig should be laid out and all the connections marked so that incorrect connections don't happen. And then there's the need for spare circuits in case something fails. I remember Nook Schoenfeld (sp?) writing something about good cable management in PLSN a few months ago. You might find that useful.
As for motor power, that can be built into the distro rack, but most people don't so they can send the distro separate from the motor control as needed.

[Pie4Weebl]

There is a large production company in Nashville that I've seen use a "3-Way" fan out. That style uses a 120v distro and the fan outs either have 3 208 connectors on them, six Edison, or 2 208 and 2 Edison on them.

[mstaylor]

As noted look at Motion labs site. I used a motor/ML distro that had the motor controls on one side and NDs for MLs on the other. Other companies have dedicated distros just to distribute to various pieces of equipment.

[WooferHound]

If you aren't using too many moving lights then you can usually use the Convenience Outlets on the dimmer rack, I think that most of them have six 20 amp outlets on them.

[epimetheus]

If you aren't using too many moving lights then you can usually use the Convenience Outlets on the dimmer rack, I think that most of them have six 20 amp outlets on them.

Not necessarily, the convenience outlets on a touring dimmer rack are normally an option, and I've rarely seen more than (2) 20A circuits.

[derekleffew]

I think WooferHound meant to say Hot Pockets (not this kind!) rather than Convenience Outlets. A touring rack usually comes with six, but may have up to twelve. Hot Pockets also appear on the patch bay, allowing use of multi-cable, whereas I don't think I've ever seen convenience outlets there. Convenience Outlets do provide a great place to plug in the snake for FOH power for consoles, however.

[bishopthomas]

Yep, depends on the distro. My dimmer rack/distro has 4 20A Edison circuits and an Edison quad with a 15A push button breaker. We typically use the 15A for FOH power and the 20's for ML's, LED's, and often power the entire PA from them as well.

[rochem]

So are Hot Pockets like this always powered (whenever the rack is powered, obviously), or are they basically like non-dims that can be switched on and off via DMX? I could be wrong, but wouldn't you normally want to be able to power your MLs on and off rather than simply leaving them powered all the time?

Also, is two-fering moving lights and other devices fairly common? Assuming the power draw of your units allowed it, would you two-fer ML power as much as possible, or is it generally advised to power each fixture individually. I can see arguments for either approach, so I'm not sure what is more common.

Thanks for all the responses!

[soundlight]

They have their own breakers either on the back panel where the outlets are located or up in the patch panel (either way, easily accessible). They are not DMX controlled.

[jeffsw6]

As moving lights generally have shutter and lamp control via DMX, it is not necessary to power them from DMX-controlled circuits. I can't imagine why you would want to use up expensive dimmer channels to power movers unless there is no other practical way to get electricity to them (limitations of available distros or cable plant?) I can imagine how a moving light, with plenty of built-in electronics, might be damaged if hooked up to a dimmer channel that was not set at 100%.

I intend to power my LED movers and cans using a simple MWBC with L14-20 connectors on the pre-wired truss, and quad boxes with "red" and "black" receptacles to identify which of two 20A circuits are available on each outlet. This cable is light-weight and inexpensive. For movers that require more power and that are placed fairly close together, ordinary multi-pin power cable and break-outs may be appropriate, but there is no need to connect the supply end of the cable to a dimmer if the available distros have unswitched, non-dimmed circuits available with multi-pin connectors. These certainly can be bought or rented.

[soundman]

Also, is two-fering moving lights and other devices fairly common? Assuming the power draw of your units allowed it, would you two-fer ML power as much as possible, or is it generally advised to power each fixture individually. I can see arguments for either approach, so I'm not sure what is more common.

Sometimes a mover will have an error that can be cleared by a hard reset. If two movers are on the same circuit and you need to reset one of them the other one looses power as well. Also by twofering you back yourself into a corner should a circuit on the multi go bad or you need to add another fixture to that location and you have already used all your spares.

[HansH]

Sometimes a mover will have an error that can be cleared by a hard reset. If two movers are on the same circuit and you need to reset one of them the other one looses power as well. Also by twofering you back yourself into a corner should a circuit on the multi go bad or you need to add another fixture to that location and you have already used all your spares.

To build on that comment -- be aware of the lamp strike in your movers. This draws significantly more power. When two-fered, this can occasionally cause the breaker to trip.

I always prefer to power moving lights off of their own individual circuit when possible. If you have to two-fer, stagger your lamp strike via remote lamp control functions on your console.

[Les]

I can't imagine why you would want to use up expensive dimmer channels to power movers unless there is no other practical way to get electricity to them (limitations of available distros or cable plant?) I can imagine how a moving light, with plenty of built-in electronics, might be damaged if hooked up to a dimmer channel that was not set at 100%.

Absolutely. It can (and usually will) cause significant damage when the dimmer is set at 100% or "Non-Dim" as well.

[bishopthomas]

I guess you guys with individual ML circuits are either using only a few fixtures or happen to have a plethora of spare circuits. As I stated, I tend to stretch my distros thin, and therefore I typically run 4 MAC250's on a circuit, up to 6 if necessary (though I will put these on the 30A breaker if I'm using a distro that has them). I have purposely built my rig (LED's and small ML's) to be able to run off wall power in a small club if need be, so I guess I am just used to loading the circuits.

[gafftapegreenia]

Can someone clarify the meaning of Hot Pocket vs. Convenience Outlet?

[Pie4Weebl]

Can someone clarify the meaning of Hot Pocket vs. Convenience Outlet?

Hey, click those links in your post!

[derekleffew]

...I intend to power my LED movers and cans using a simple MWBC with L14-20 connectors on the pre-wired truss, ...

Of course the OPD supplying that MWBC will be equipped with handle ties or other common-trip provision, correct? What happens if you want to power down only one of the circuits (such as for a hard reset)?

If your 120/240V distro is powered by two legs of a 120/208Y system, is an over-sized neutral not required?

[jeffsw6]

Of course the OPD supplying that MWBC will be equipped with handle ties or other common-trip provision, correct? What happens if you want to power down only one of the circuits (such as for a hard reset)?

The trade-off for conserving copper, while meeting the handle-tie/common trip requirement for MWBCs, is not being able to cycle only one of the two phase legs by using the circuit breakers. I can easily live with this limitation given the low-caliber work I am doing.

If your 120/240V distro is powered by two legs of a 120/208Y system, is an over-sized neutral not required?

Not in my case, since these are LED fixtures, not ordinary dimmers. With dimmer loads, certainly the neutral of MWBCs must often be over-sized; and the code provides some guidelines in this area.

[rochem]

Can someone clarify the meaning of Hot Pocket vs. Convenience Outlet?

Hey, click those links in your post!

While we're talking terminology, what would the proper term be for Non-Dimmed power that was switchable (on-off only) via DMX from the lighting console? I'm mainly referring to a Non-Dim module in a Sensor+ rack (NOT a regular dimmer set to Non-Dim). I've heard the term Relay for this, but is that correct?

Sometimes a mover will have an error that can be cleared by a hard reset. If two movers are on the same circuit and you need to reset one of them the other one looses power as well. Also by twofering you back yourself into a corner should a circuit on the multi go bad or you need to add another fixture to that location and you have already used all your spares.

I think some people misinterpreted what I was trying to ask before, so I'll clarify: given the choice, would you choose to put your ML power on a DMX controlled Non-Dim power source (NOT a dimmer set to Non-Dim), or is it more common to just have it on constant power so the only way to turn it off is via the circuit breakers? In the case of needing a hard power reset, would you ever want to kill Mover power by turning the Mover Power channel on the board off, or would you just walk to the actual dimmer rack and cycle the circuit breaker? This would have the result that every night when you powered off the board (if you did so - that's a different discussion), your Mover Power would also turn off. Do you usually stop the flow of power to your movers when you go home for the night (from the source, since adjusting the physical switch on each fixture is usually impractical), or is lamping down usually enough?

Thanks!

[Pie4Weebl]

While we're talking terminology, what would the proper term be for Non-Dimmed power that was switchable (on-off only) via DMX from the lighting console? I'm mainly referring to a Non-Dim module in a Sensor+ rack (NOT a regular dimmer set to Non-Dim). I've heard the term Relay for this, but is that correct?

Both terms are acceptable, though "non-dim module" is pretty ETC specific. For a standalone product, you will be able to find "DMX relays".

[gafftapegreenia]

There are two reasons why I think most people wouldn't use a rack of DMX relays to control power:

1) It's a new piece of equipment to be trucked, to fail, to need repairs, and overall cost money. Where is the benefit of adding another point of failure in the chain just to allow one to remotely switch the circuit that powers a ML on and off when most modern ML's can have their power up/down sequences initiated remotely?

2) Just like on most follow spots, most ML's have fans. When one uses the board to send a DMX signal that tells the ML to lamp down, the fan will continue to run for quite a while to cool the fixture. If one where to just kill the power outright, they risk doing heat damage to the unit by preventing the fans to complete the cooling cycle. (The same is true with projectors)

[mstaylor]

I think some people misinterpreted what I was trying to ask before, so I'll clarify: given the choice, would you choose to put your ML power on a DMX controlled Non-Dim power source (NOT a dimmer set to Non-Dim), or is it more common to just have it on constant power so the only way to turn it off is via the circuit breakers? In the case of needing a hard power reset, would you ever want to kill Mover power by turning the Mover Power channel on the board off, or would you just walk to the actual dimmer rack and cycle the circuit breaker?

While possible to tie MLs to DMX nondims there is no advantage. If you need to restrike then you can do it from the board, if you need to a hard restart then do it at the breaker.

[derekleffew]

Both terms are acceptable, though "non-dim module" is pretty ETC specific. For a standalone product, you will be able to find "DMX relays".

I'd argue that "non-dim module" is not manufacturer-specific at all, unlike R20 (Relay Module) and CC20 (Constant Current). As for DMX Relay, there's Doug Fleenor Design -.

...what would the proper term be for Non-Dimmed power that was switchable (on-off only) via DMX from the lighting console? ...

"DMX-controlled, switched power." Not to be confused with the "swtiched" setting of a dimmer on the CEM.

...given the choice, would you choose to put your ML power on a DMX controlled Non-Dim power source (NOT a dimmer set to Non-Dim), or is it more common to just have it on constant power so the only way to turn it off is via the circuit breakers? ...

I think the answer largely depends on whether it's a touring or permanent installation. For tours, the ML PD is just a bunch of dumb breakers. If something needs to be reset, the LBO says on com, "Hey, dimmer b!tch, reset light#XXX." For a permanent installation, ML power can be provided by an ETC SmartSwitch, or similar by other manufacturers. I don't know of anyone making a touring version. Even when using DMX-controlled relays, it still may be more expedient for the LBO to tell someone backstage to do it rather than look up the correct number and park the offending channel/dimmer/address/output, then wait the appropriate time, then unpark, etc.

As for removing power to MLs overnight, see the threads Control/Dimming Non-Permanent Shutdown Procedures - View Poll Results and Shutting down .

[soundlight]

As a note, on Leprecon racks, there is a row of "NDs" or "Non-Dims" in the patch panel that are breaker-controlled outlets much like the described hot-pockets. 4 patch points per ND, as with any dimmer patch in the rack. There are 6 NDs in all of the Lep racks that I test at work (24s, 36s, and 48s - most are VX series, I think), and as for outlets on the back, I think that there's 2 convenience circuits with breakers on the back and then there're the X-outlets, which are six patchable outlets - mix of stagepin and edison connectors.

So Non-Dim isn't exactly something that I'd use to exclusively refer to the ETC R20 module - in fact, I've always called it a Relay module, and always heard it referred to as such.

As for switching ML power from the rack, as was mentioned by Derek: For a touring situation, why do it - more of a chance of it getting messed up. Use an ML Distro. For an installation or just for a theatre that switches out modules in the rack for ML power depending on the show, yeah the ability to switch off MLs from the console is nice. Back in college when we powered movers from the dimmer rack, I would have a power up macro that would power (park) on all of the appropriate circuits, home all of the movers (Ibeams need to be told twice), and run everything to limits. There was also a power down macro that doused the lamps and then waited before powering everything down.