Control/Dimming - New Black Box Theater - Need Power Advice.

[spotlightondance]

Howdy,

We're adding a multi-use Dance Studio / Black Box Theater to our Dance Studio facility.

The building owner is putting 200A 3-phase power dedicated for this room, 60A of which will be spoken for by the new HVAC system. By my reckkoning, that leaves 140A remaining for potential Lighting system use. All other service in the building is done through a seperate single phase panel so there's no potential other use for the 3-phase.

The performing / studio space is pretty small, about 1500 sq. ft. and when doing performances in there, we'd expect the area needing lighting to be no bigger than 20' X 30'.

Preface - We will be talking to a lighting supply house / electricians about this but I'd like to have some idea what I'm talking about.

First question - Is 140 A 3-Phase service going to be enough?

Second question - Any recommendations for best practice on interfacing the panel to dimmers? Cam Lok? Direct?

Third question - What 's the most cost effective approach for dimmers? Wall mount, rack mount, portable?

Last Question - Any specific recommendations for dimmer brands for something like this?

Thanks in advance!

[coldnorth57]

One more question how long do you plan to stry in this space and are you going to do any show in other venues?

[spotlightondance]

1) We will be in the space at least 9 years.

2) We do have annual recitals in two different venues. One of which our lighting guy has to rent a couple of dimmer paks, perhaps 12 channels total, to augment the house system. Not sure what type they are however.

Also, I was just corrected, the HVAC system only draws 40A. Leaving 160 available.

Thanks!

[fredthe]

When considering permanent vs. portable dimmers, another consideration will be the wiring from the instruments to the dimmers. Will the space have a lighting grid of some sort? Will there be permanent dimmer outlets on the grid? Or, are you expecting to run single or multi cable from the dimmers to the lights.

I would expect your installation costs to be higher for fixed dimmers, but your equipment/cable costs to be higher for portable.... but this is just a SWAG.

Also, will houselights be on the same dimmers/feed?

Will power for sound come from the single-phase panel?

Are you planning any non-dim power for accessories (scrollers, etc) or moving lights?

Make sure you accounting for everything that would be fed form this service... I could easily see you only having 100A-120A (per phase) to feed your dimmers.

-Fred

[Grog12]

Second question - Any recommendations for best practice on interfacing the panel to dimmers? Cam Lok? Direct?

ToS limits us from giving you an answer to this question. Honestly if you have to ask it, then you're probably not qualified to be interfacing your dimmers with the panel.

All in all it will depend on whether you do portable or permanant dimers.

My firm suggestion consult a qualifed eletrician in your area.

[fredthe]

My firm suggestion consult a qualifed eletrician in your area.

I think you're being a bit harsh... he already said he's going to be talking to electricians, he just want's to be sure he's asking the right questions. Many electricians won't have a clue what a company switch is.

It should be pointed out that if they are going with protable dimmers, they will need someone qualified to connect/disconnect the dimmers from the service.

-Fred

[TupeloTechie]

I think you're being a bit harsh...

Welcome to ControlBooth...

[Grog12]

I think you're being a bit harsh... he already said he's going to be talking to electricians, he just want's to be sure he's asking the right questions. Many electricians won't have a clue what a company switch is.

It should be pointed out that if they are going with protable dimmers, they will need someone qualified to connect/disconnect the dimmers from the service.

-Fred

In situations dealing with electricity, especially when it comes to doing "tie-ins" I'd rather be a bit harsh and safe, than not.

Yes, the OP said he was going to talk to both his supplier and a qualified proffesional, but there are certain things our TOS limits.

This is one of them.

Also, let me clarify what I'm trying to avoid here: The OP asked about best practices for interfacing dimmers using cam's and direct tie-ins. I'm trying to avoid discusion about how to use either while installing the racks. Best practices usually means "how to" when you're setting up a system. Such as it's the best practice to hang a light right side up.

[gafftaper]

Yeah sadly we can't talk about specific tie in details, but a professional theater electrician will be able to set it all up for you.

I believe you said you are in Vermont. Do you need help locating a dealer?

There are so many variables it's hard to suggest permanent vs. portable. I suggest you get a dealer in there to give you some price quotes on options.

Do you need more power? If you plan more than just a primitive system YES. A standard single dimmer these days is 2,400 watts/110V= 20 amps. My black box theater has 196 dimmers... so yeah I use a little more than 140 amps. I helped setup a dance studio a few years ago they installed FOUR- 12 channels x2,400 watt dimmer packs... at about 250 amps each if my math is correct. That was about right for a nice sized dance studio

As far as brands of both dimmers and light control boards. ETC (Electronic Theater Controls) set's the bar high in product quality and service. Strand products are not far behind (depending on who you talk to). Some of the other manufacturers out there are a solid choice some are not. Do you best to get an ETC or Strand system. If you get price quotes on something else check back with us to see what we think of the brand.

Another interesting option would to consider would be going with no dimmers. Just distribute non-dimmed power all over the place and go with all LED's and non-dimmed moving lights. It would be very interesting to discuss pricing on this strategy with a dealer. SOMEDAY that's the way all new theaters will be built. You can use far less power this way, the building will be cooler (lower cost on HVAC)... lots of positives. It might be a little higher priced initially than going the traditional route but if you have the money the long term benefits of going all LED might be worth it. You also are putting all your money into fixtures that you can take with you to another space if you need to move. Going all LED would also mean you could easily get away with not upgrading your 140 amps.

Tell us more about what you do in the space. What are your expectations for the lighting system? What is your budget? How large is it. Again is there a lighting grid already installed or are you doing that at this time too? What do you plan to use to control the lights?

Pictures could be helpful.

[derekleffew]

...Do you need more power? If you plan more than just a primitive system YES. A standard single dimmer these days is 2,400 watts/110V= 20 amps. My black box theater has 196 dimmers... so yeah I use a little more than 140 amps. I helped setup a dance studio a few years ago they installed FOUR- 12 channels x2,400 watt dimmer packs... at about 250 amps each if my math is correct. That was about right for a nice sized dance studio. ...

The quantity and capacity of the dimmers does not determine the supply. The connected load determines the supply. See Dimmer feeds--How much power is enough?. Given a 140A/leg 120/208V 3Ø Wye-Connected 4W+G service, a maximum of Eighty-Seven 575w fixtures could be connected. That sounds adequate for a performance area of 20'x30', in a 1500 sq. ft. venue.

First question - Is 140 A 3-Phase service going to be enough?

In all probability, yes. Unless you're planning on presenting the American Ballet Theatre.

Second question - Any recommendations for best practice on interfacing the panel to dimmers? Cam Lok? Direct?

Depends on the answer to #3.

Third question - What's the most cost effective approach for dimmers? Wall mount, rack mount, portable?

Since you're likely talking about 24-48 dimmers/circuits, a wall mount rack is probably the most cost-effective. Install equipment is cheaper than portable, but is offset somewhat by installation labor costs.

Last Question - Any specific recommendations for dimmer brands for something like this?

ETC, Strand, and Leviton are the top tier. Second tier includes EDI, Teatronics, ET, Leprecon, Lehigh.

Questions for you:
Have you chosen a console?
Do you have an existing inventory of fixtures?
Who will be "doing lights" (professional, volunteer, janitor)?
Will the houselight system be separate from the stage light system?
Do you have an architect or someone who will check your plans for code compliance?
Notice how the questions keep getting longer--have you considered engaging a theatre consultant?

[Van]

...--have you considered engaging a theatre consultant?

I've considered strangling several, over the years.

Having a couple of small black boxes myself I can tell you the idea of a small to medium sized rack mount < permanent> system and the installation of a company switch for touring groups to tie-into, "tis a consumption devoutly to be wished."

[spotlightondance]

Appreciate the comment about the ABT. Actually, the Artistic Director of the ABT has been in our space before. He's the brother of one of our employees.

Great discussion, very helpful in clarifying exactly how much I don't know about this stuff.

Have you chosen a console?

No.

Do you have an existing inventory of fixtures?

No


Who will be "doing lights" (professional, volunteer, janitor)?

Sometimes Pro, sometimes me.

Will the houselight system be separate from the stage light system?

Yes, all other service in the room is from another panel.


Do you have an architect or someone who will check your plans for code compliance?

Yes

[mstaylor]

Make sure when you consult an electrician that he has knowledge of both theatrical electricity and local codes. If this not possible the youwill need two electricians. Believe me, I had a huge problem with a lighting company that had no business selling anything and an electrician that had no clue and no desire to understand theatrical lighting.

[Van]

Make sure when you consult an electrician that he has knowledge of both theatrical electricity and local codes. If this not possible the youwill need two electricians. Believe me, I had a huge problem with a lighting company that had no business selling anything and an electrician that had no clue and no desire to understand theatrical lighting.

A fellow technician of mine once went to a Theatre to do the engineering check-off and system initial power on, only to find the electrical contractor who had installed the outlet races had installed common neutrals
a project that was already a week late, got even later...

[gafftaper]

The quantity and capacity of the dimmers does not determine the supply. The connected load determines the supply. See Dimmer feeds--How much power is enough?. Given a 140A/leg 120/208V 3Ø Wye-Connected 4W+G service, a maximum of Eighty-Seven 575w fixtures could be connected. That sounds adequate for a performance area of 20'x30', in a 1500 sq. ft. venue.

My Bad... forgot the 208V in the equation. While yes you can power Eighty-Seven 575w fixtures. In order to get that many fixtures you will have to gang them together 3 or 4 on the same circuit. That's not a terrible thing, but it does mean you will not have a lot of independent control of fixtures if you stay with only 140A.

No one has commented on my idea of ditching the dimmers and going all LED's and Movers. If you don't spend thousands of dollars on Dimmers and Raceways you have a lot of money left to buy LED toys. We have a tiny stage we are going to put into the new student union at the college (about 12x8). We are going to skip the dimmers and just install a dozen 1' Seladors. No need for dimmers, no need for raceways, an electrician can run a couple standard circuits and I've got all the power I need. It's cooler. Lots of color flexibility. True you can;t use a gobo, but that's not a problem in simple setups. In the case of the dance studio mix in a couple of movers to go with the LED wash and you get your texture as well.

[fredthe]

No one has commented on my idea of ditching the dimmers and going all LED's and Movers.

OK, I'll comment... I think it's an excellent idea, and definatly worth investigating. In fact, I wish I had thought of it when reviewing the specs for addition of a small lighting setup to a theater classroom (with a small stage area) last year. It would have been perfect.

The question is, with today's technology, how small does the space need to be for this to be effective?

Another approach (borrowing on a couple of your ideas ) would be to do LEDs, plus 1 or 2 2400W 6-packs and a few conventional fixtures (with perhaps Scrollers, iQues, etc.) instead of moving lights for patterns and specials.

-Fred

[Footer]

Inrush current. When a motor starts, it takes more power then it takes when it runs. You don't really have 140 amps. Some motors take 3x as much power to start up. So, if the contractor is installing 30amps of motors it could easily take 80 to 90 amps to start the system up. I don't think you have enough power to do what you want to do unless they are already factoring in the inrush. Granted they usually do staged startups, but it is still a consideration.

Ask the contractor/engineer about this. It would be bad if you loaded up to your theoretical 140amps and the AC kicks on and you blow the panel. Most places do not understand how much power it actually takes to light a show so they will gang up things like HVAC on the same panel.

[mstaylor]

One solution to the start-up problem for the AC is to use a rampup coil to start the equipment. It keeps from pulling so much power and if you have the bag type ducts that are becoming popular it keeps from filling so fast that they scare the audience.

[mrb]

(I skimmed over the thread and didnt notice mention of this, sorry if someone else already pointed it out)

You need to double check what this 200a 3ph service is. It is not common for a building to have both a 120/240 single phase, and a 120/208Y three phase service. It is very possible your 3ph service is 240 delta which would require a 240D-208Y120 transformer to be able to supply dimmers.

[derekleffew]

...While yes you can power Eighty-Seven 575w fixtures. In order to get that many fixtures you will have to gang them together 3 or 4 on the same circuit. That's not a terrible thing, but it does mean you will not have a lot of independent control of fixtures if you stay with only 140A. ...

Because independent control of fixtures requires more power than 3 or 4 on the same circuit? Lighting dance is generally about broad strokes and washes, not finicky specials shuttered with hairline precision.

...No one has commented on my idea of ditching the dimmers and going all LED's and Movers. ... In the case of the dance studio mix in a couple of movers to go with the LED wash and you get your texture as well.

I wouldn't want to light any stage solely with soft-edged LED fixtures, especially dance. Advocating moving lights for a less than fully professionally-staffed facility seems contrary to the Gafftaper Method, doesn't it?

[SHARYNF]

200 amp 3 phase supply is a very standard business in an industrial setting electrical service. Going forward theatrical equipment power needs are moving in the direction of lower requirements. We have gone from the days where 1000watt FEL's were the "standard" to 575 -750 today.

So as with all things it really comes down to cost, it might be interesting to get an estimate on a 400 amp service and compare the differential.

Cam Lok is pretty standard for PORTABLE type of install, typically where you might have a production that is bringing in a a significant set of outside gear for the event. Most of these setups come in the typical 100 amp 3 phase, 200 amp and then 400 amp. If I had my preference it would be for a clean 200 amp three phase service and have the HVAC connected indepentantly. Main reason is that as a personal preference I would rather have a dedicated panel. Just as you saw in your early posting was it 60 amp or 40 amp etc. In addition TYPICALLY if there is a single phase panel for the "rest" it is going to be derived from the building service, since it is pretty rare to have both a three phase and single supply to the BUILDING, it is more typical to have three phase supply and then split off a single phase panel and then a 3 phase panel, SO the likely hood is that at the main feed to the building there is more than 200 amps.


So IMO if you want to have equipment that you or someone else rolls in and out then a Cam Lok setup has the advantage of industry standard connection. If you are really only looking at using your own gear, then direct wired in is more typical.

The fixed rack solution is typically more cost effective BUT does require more planning to make sure your dimming circuits are where you need them for the productions you are going to do.

For small highly variable productions I tend to use Portable Packs so I can add what dimming I need to where I need it. In the past typically the need was for 2400 watts per channel, but these days IMO 1200 watts/per channel is more common with 48 channels total being pretty common for my needs in a small situation.
I have tended to use more LED's these days for saturated colors, reducing the need for high watt pars. A lot of the somewhat large dimmer setups in the past were needed to support the high number of pars all at say 1000 watts and each with a dedicated color. While LED's today are not good for everything, they do have a place in saturated colors IMO and these don't need any dedicated dimmer. This also has tended to support my move to using portable packs. As an aside the move to lower wattage instruments also will reduce the capacity requirement for the HVAC system, so longer term you wind up with lower Electric bills, lower HVC requirements etc. Granted we are not there yet for total deployment of LED's but progress is being made.



Sharyn

[gpforet]

No one has commented on my idea of ditching the dimmers and going all LED's and Movers.

LEDs are certainly a possibility for washes provided they support theatrical dimming (which means something like the COLORado at about $700/intrument). I've yet to find LEDs which provide the focusing, shuttering, and gobo support I can get from a source 4. So, you'll still need conventional fixtures for front lighting. For the cost of a couple of movers I can buy quite a few channels of dimming and source 4's. I have been doing black box productions for many, many years, and have never needed movers for black box. In fact, in the dozens of productions I have done in the last two years, I have only needed to rent movers twice. I have worked theatrical venues with 8 movers on the first cat, with the logic that with movers, the lights would never have to be moved......wrong. And for the cost of those 8 movers, I could have hung 24 source fours and paid for the dimming to support them.

I am currently looking at outfitting a small community theatre with LED washes, but the problem with LEDs is dimming, they tend to step down during fades, rather than smooth fades, and I've yet to find an LED fixture for less than $700 which provides this smooth dimming, which I think is absolutely neccesary for theatre work.

[church]

just a comment you may want to think about. You have said that the HVAC will require 40A per leg and the other 160A is available for lighting. You may want to check that the HVAc is correctly sized for the heatload of the lighting and audience. If not you may have less power for lighting or you will have to overcool a room prior to a performance to allow the temp to creep up due to the heat from people and lighting.

If this has not already been considered then you may want involve specialist help beyond what is already being considered.

[spotlightondance]

Again, all great info. I really appreciate it.

I'm beginning to think that a combination of LED washes and conventional front with box dimmers on the grid would be a good choice to start. This keeps me out of the business of doing a big dimmer install and it sounds like over time LEDs will become a more viable options as our needs grow somewhat.

We'll be doing some dance, some cabaret and some very small cast theater pieces to begin. If I am working with about a 25 x 16 foot playing space, how many COLORado units would folks recommend?

[Les]

If you are considering doing the portable route, you might take a look at the ETC Smartbars.

[SteveB]

(I skimmed over the thread and didnt notice mention of this, sorry if someone else already pointed it out)

You need to double check what this 200a 3ph service is. It is not common for a building to have both a 120/240 single phase, and a 120/208Y three phase service. It is very possible your 3ph service is 240 delta which would require a 240D-208Y120 transformer to be able to supply dimmers.

In my experiences, it's rare to see distributed panels in single phase, when the building service and primary feed panels are 120/208v 3 phase. There's no cost advantage to using single phase panels as among all the other issues, the electrical engineers have to pay very close attention to load balancing when moving down to 2 hots. In fact I have NEVER seen a building that had 3 phase as the initial building feed where there were any single phase panels in use and if that's been the experiences of others, one would question WHY ? (did they do it that way ?).

Coming into the rest of this late (I was camping in Maine), we are currently going thru the same type of process/design issues for a new facility, where one space is a Dept. of Theater "rehearsal" room, slash Black Box. The solution for us was 15-18 or so TwistLok type receptacles @20-30amps, 3 phase ea., feeding Lex Producs (or approved equal) Anaconda 6x1200w dimmer packs, to be placed throughout the room as the design required. One of the advantages over a dedicated centralized dimming (rack mount) system, is the TwistLok type receptacles can do double duty as ML, LED, scroller power, etc... down the road.

Some of the issues we faced and are still dealing with (and that you face as well):

- The feed breakers for distributed dimming/power, usually 20 or 30 amp rated, are not usually rated for continuous loading - I.E. an incandescent load for more then 3 hrs. (do your rehearsals run more then 3 hrs. ?, planning on doing a TV/Film shoot ?) Using standard panel breakers in this fashion requires down-rating by 20%, thus the breaker can now only deliver 16 amps @ 120v = 1920 watts, per phase. That complicates the loading using 575w lamps, as well as 750w and prevents 2 1kw units on the same circuit. That's not the case with a typical centralized dimming systems, whose load breakers are rated for continuous operation at 20 amps. The loading issue as well as the types of available portable packs moved us away (for the current design) from Smart Packs, and Smart Bars, towards the Anaconda system, as it had 6x1200 watts in a pack, which SmartPack doesn't offer and we don't want a "Bar" for ease of movement.

- Forcing the powers that be to buy 2 Sensor dimmer racks @ 192 dimmers @ 2.4kw ea., is somewhat more difficult (due to install costs) then buying an equivalent number of 1200w dimmers in portable 6 packs, as you know what's going thru the minds of the electrical engineer AND the theater consultant AND the architect, is the thought that "They don't really need all those dimmers" with the result that down the road, as the building finds it's cost over-runs, the equipment left for the end of the project to get purchased (dimmer packs, cable, lighting equipment) will find it's budget slashed. Get ready for it as it will happen. One way around this is to insist up front for an equipment budget that is isolated from building construction costs, and maybe insist on equipment purchases at the start of the project.

- Run Ethernet everywhere. Run a ton of it. Run more then you can ever imagine needing. Use 3Com IntelliJacks for outlets. Have them make room for a big rack of electronics with all the Cat5 for lighting coming down to it. Put the rack somewhere easy to get to.

Steve B.

[mrb]

In my experiences, it's rare to see distributed panels in single phase, when the building service and primary feed panels are 120/208v 3 phase. There's no cost advantage to using single phase panels as among all the other issues, the electrical engineers have to pay very close attention to load balancing when moving down to 2 hots. In fact I have NEVER seen a building that had 3 phase as the initial building feed where there were any single phase panels in use and if that's been the experiences of others, one would question WHY ? (did they do it that way ?).

Steve B.

re read the first post, then what I wrote. The OP said the building is currently served by a single phase service, and that the landlord is adding 200a 3ph service.

It is very common, (my building even has this) to have a 120/240v single phase, plus a 240v 3 wire delta three phase service. Many utilities dont even offer 120/208Y unless you have your own transformer (primary service).

Since you cant have two services of the same type/voltage, I suspect this new service for the A/C is 240 Delta, which is useless for lighting unless you install a 240D - 208Y120 transformer (this has its own issues).

(note: I am talking about services here, not subpanels coming from a main somewhere)

[SHARYNF]

the Lex anaconda Packs in the 6x1200 version that I am familiar with are NOT set up for 3 phase but are usually running with two independent 120volt input feeds. If the breakers are tripping on a continuous load of 20 or 30 amps I would check to see if the problem is the unbalancing. These dimmer packs (again the anaconda's that I am familiar with) need to have TWO Neutrals. I would speculate that someone is wiring them with a single neutral, it is an unbalanced load and that is what is tripping the breaker. Ordinarily in my experience they will run properly all day long on the rated 20 amp breaker.

My guess is that some electrician decided to get clever and wired these up using two legs of the 3 phase and a single neutral and that this is the route of the problem ie an unbalanced over used neutral

Sharyn

[FMEng]

The National Electrical Code only allows any circuit to be loaded to 80% of its rated capacity. That breaker rated for 200 Amps can have an actual load on it of 160 Amps.

But, the same is true for the HVAC breaker. If you have been told it uses a 40 Amp breaker, the predicted load is 32 Amps or less.

Properly sizing the neutral to handle loads with high levels of harmonics is another problem. Lighting dimmers are a textbook example of harmonic rich loads. More than a few building fires have been caused by errors with this.

These are just a couple of details that illustrates why you need, at the very least, a well versed electrican, or better yet, an electrical engineer to design this system. If you don't have expert help, then I would allow for a big safety margin between predicted load and over-current ratings.

[FMEng]

Since you cant have two services of the same type/voltage, I suspect this new service for the A/C is 240 Delta, which is useless for lighting unless you install a 240D - 208Y120 transformer (this has its own issues).

(note: I am talking about services here, not subpanels coming from a main somewhere)

You can have more than one electrical service in a building, but the NEC lays out some specific requirements about how it has to be done. As I recall, the disconnects for both need to be clearly marked that it is one of two (or more), and they may need to be within sight of each other. Again, a knowledgeable consultant can work out this issue.

[avkid]

You can have more than one electrical service in a building, but the NEC lays out some specific requirements about how it has to be done.

While it is allowed under NEC most utility companies will not allow it unless you have a large industrial facility.

[mrb]

You can have more than one electrical service in a building, but the NEC lays out some specific requirements about how it has to be done. As I recall, the disconnects for both need to be clearly marked that it is one of two (or more), and they may need to be within sight of each other. Again, a knowledgeable consultant can work out this issue.

You cant have multiple services of the same voltage/type until you get into situations where a single service is not feasible. This is dictated more by the power company regulations than the NEC. For example you cannot have two 200a 120/208Y services, but you can have a 200a 120/240 and a 240D, but not a 120/240D and a 240D.

I am curious as to what the OP really has.....

[SteveB]

the Lex anaconda Packs in the 6x1200 version that I am familiar with are NOT set up for 3 phase but are usually running with two independent 120volt input feeds.

Sharyn

The Anaconda 6x1.2kw Stage Pin pack on the website, clearly shows 3 power feeds with male Edison connectors. I'm told this model can be provided with a #12/5 SOOW power cable for 3 phase supply. In any event, as our construction is well over a year away, we have as yet, not finalized the nitty gritty details about power and packs and I wouldn't be surprised to hear from the consultants that all has changed !.

Dimming & Control: Anaconda 6 Channel 1200 W Stage Pin Dimmer | Lex Products

SB

[SHARYNF]

Just took a second look the anacondas were the 4 channel version with two power feeds. Looks like the 6 packs are different, the pdf files had not been updated for the 6 pack versions.

the whole three phase supply and neutral sizing is an issue these days. If you are using three phase as a supply for a three phase device, then at least in theory the neutral should be properly sized. Where it gets a bit more complex is when you use the three phase supply to feed three single phase devices, then best practice seems to be to up the size of the neutral.. I had one of the Pagoda packs from Lex and discusses this with them and they actually made up a special neutral double rated harness for me to install.

SO just a suggestion but typically if you are going to run a three phase supply to feed three independant connections, then usually you need to have three independant neutrals. A lot of electrical contractors still don't do this. The whole issue of shared neutrals with three phase supplies being used as you are looking to do requires careful planning.

In my experience, if you are looking to run three phase to 5 wire outlets, and then have the option of plugging in an adaptor that splits these out to 3 single phase outlets, then again in my experience you need to either run 3 independant neutrals OR double rate the neutral. Most of the run of the mill electrical contractors don't understand this or do this. Neutral overload in unbalanced situations has become more of an issue. Getting it done properly during install is FAR FAR cheaper then later.

Just a thought
Sharyn

[mrb]

Neutral overload in unbalanced situations has become more of an issue. Getting it done properly during install is FAR FAR cheaper then later.

Just a thought
Sharyn

neutral overload doesnt come from unbalanced loads, it comes from non linear loads. This is why dimmer outputs must be neutral per circuit, and we sometimes see 200% neutral on feeders supplying non linear loads. In supplying something like a L21-20 for a 6x 1200 anaconda, I would spec #10 for the phase conductors and a #8 for the neutral. The supply cord on the pack should really be 10/5.

[church]

FMEng has made a good point about this type of system requiring an engineer to do the design. These threads are good for information and learning but performing this type of work is something else: and can put you into things you would prefer to avoid.

If you are in Canada all of the provinces restrict this type of design work to a licenced professional engineer. There are many issues to be addressed only some of which have been mentioned in this thread. If you do it regardless and get caught by the provincial engineering association then expect to be fined, if the owner of the facility experiences a problem because of what you have done you are financially liable even if there is no contract and if you have liability insurance you can expect your insurer to refuse to pay. If someone gets injured or worse killed you are in more trouble than you can imagine.