Welcome to BigScreenBiz.com

I've got to submit to our electrical engineer who is designing the "Power layout" for our drive-in, a table of "electrical loads" for our building, and had a question about the booth load requirements.

I've got plenty of power available from the street, as 3 phase power is already run to the site at the edge of the road.

My current lamphouse in storage is an 4kw ORC, but have considered replacing it with either a Strong or a Xenex II. I noticed when I removed my ORC from it's former booth that it had both 3 phase running to the power supply, and a 120v circuit run to the lamphouse controls... or something like that. I've got to tell my electrical engineer what size circuits to install and I don't have a clue.

My projector is a Simplex XL with a RCA 9030 soundhead. I was figuring a 30amp 120v dedicated circuit would handle the projector, and another 20amp 120v dedicated circuit to cover the platter and MUT.

Our theatre will end up being a twin screen by the beginning of 2004, but will open in May of 2003 with one screen. I'm having the engineer size the service entrance and panel board to accomodate both screens for ease of expansion in the future, but I need to tell him what to put in there now.

Any help would be appreciated....

I don’t know about a Drive-In but this is what I understand that each auditorium needs in an indoor multiplex.

Ask for Switch able Circuit Breakers as you may be turning these off each night.

3 Phase 30amp circuit for the Lamphouse
120v 20amp Exhaust Fan
120v 20amp Projector
120v 20amp Platter
120v 20amp Make-Up Area (Only one needed per complex)
120v 20amp Accessory Plugs in Booth
120v 20amp Sound Processor
120v 20amp for each 2 Amplifiers
120v 20amp for each House Dimmer
120v 20amp Isle Lights
120v 20amp Auditorium Plugs for vacuums, blowers and such (Leave on 24 Hours)
120v 20amp Emergency Lights & Exit Signs (Leave on 24 Hours)
120v 20amp Clean-Up Lights (Leave in 24 Hours)

The load on each circuit will be low, but this is a great way to isolate each circuit for service and diagnosis. This can probably be served with a 200amp panel.

I answered this on http://www.film-tech.com , but it will be interesting to see what other drive-in owners say. As I said, install enough capacity and circuits to handle future needs. Don't forget lightning protection and emergency lighting and announcement capability. Isolate and condition circuits supplying digital equipment.

---

John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: 585-477-5325 Cell: 585-781-4036 Fax: 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion

Thanks to both John & Ian..... I've posted this question here, Film-Tech, and the Drive-In Owners Association message forums. I wanted to get as much information as I could before I meet with him on Tuesday.

John had mentioned "lightning protection" for the booth, I'm assuming for stray random strikes in the field running in on the field speakers. We will not have any field speakers... now days they're just too costly to maintain, and also expensive to install.
I've got an FM stereo transmitter that runs at a 1/2 watt that won't broadcast the signal much further than the property boundaries.

A direct "hit" on any portion of your electrical system is likely to cause damage. For example, field lights at the top of your screen are likely to eventually get struck, which will cause a surge that can damage other electrical equipment.

---

John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: 585-477-5325 Cell: 585-781-4036 Fax: 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion

I'm bringing up this old thread because I have a question about power requirements.

I've read in the lamphouse power supply manuals that they accept either 3 phase or single phase electrical input. Assuming I have a choice to go either way, what are the advantages or disadvantages of each? Which should I go with?

If I don't have the option of 3 phase power, is single phase ok?

This is an old one brought back to life!!

From what I understand, any lamphouse 4k and above will need 3 phase for the power supply. I've seen 2 - 2k rectifiers wired together to light a 4k lamphouse before in a booth where there was no 3 phase power, but it's not very common.

Here it is almost 5 years later. We ended up installing an 800 amp 3 phase electrical service in our drive-in, and we are almost maxed out.

Hey Barry, nice to see that you are still around 5 years later, in business and still posting to this forum. The fact that there are many experienced people who continue to participate here after several years is yet one more reason that this forum rocks!

Actually, my interest in this topic is more about hard tops than drive-ins. I don't foresee a need for anywhere near a 4k lamphouse. But when I read this thread, the first thing that Large listed was 3 phase power for the lamphouse (and he did say the list was for an indoor). Yet when reading a few manuals I saw that the power input is listed as either single phase or 3 phase. Honestly, I don't yet know what my building has available, but I do know that I have been asked to provide an equipment list for the engineer. I've also been told that I will have to bring the electrical system up to code, so if 3 phase is needed, now is the time to bite the bullet.

I need to find out if the building has been wired for 3 phase already since it was a cinema before, but even if it has 3 phase, I'm not sure if using it would be the best choice. Can someone please tell me why 3 phase is good for the lamphouse?

I've read elsewhere that 3 phase power doesn't usually save on the electric bill, so it's not as simple a choice as 110v versus 220v. It must have something to do with the quality of projection or maybe it affects the life of the equipment???

It just seems like somewhere in the manuals it should say which is the preferred input and why. I couldn't find it there, so I thought I would ask here, hoping to find someone in the know.

Can anyone clear this up for me?

Thanks to Barry for giving some guidance. Others who are looking at larger lamphouses now know they need 3 phase power, and lots of it.

What about the smaller 2k variety? It appears that many recommend 3 phase, and it wouldn't be an option on the equipment if it was a bad idea, but what is the affect of using single phase power? It could save on the electric bill, but is that at the expense of a good picture?

It all depends on the make & model of the power supply in question as to 3 phase or single phase. In general, the Switching power supllies made by Strong can accept single or 3 phase for power in models intended to operate a 3kw or smaller wattage bulb. If you're operating a 4kw or bigger bulb then you need 3 phase for sure.

Some thoughts that might help:

First, a watt is a watt. Whether it's pulled from one leg, two, or from a 3-phase service, it's still a watt and you're going to pay for it. The point is really more a matter of what your incoming power service will provide, how well your building is wired and whether you have single items that draw large amounts of power.

Between 2,500 and 3,000 watts, most lamphouses make the transition from 1 to 3 phase supplies, mainly because 3 phase handles these larger loads without everything in your building dimming when they're turned on. Yes, these things can be run on single phase, but the size of the incoming service becomes more of a factor.

There are 3 ways you can get from 3,000 to 4,000 watts out of single-phase service, ASSUMING your building can handle the load and you haven't already used up your capacity.

A couple of older 2,000 watt supplies can be wired in parallel, each providing half the power. They run on single phase. There's a drive-in that did that recently with good results (Barry also knows about this).

You can also do this by using one of Strong's 7,000 watt switching supplies. They will provide up to 4,000 watts if connected to single phase (and they're ok with this... it's in the book).

Finally, rotary phase convertors will provide 3 phase power from single phase sources. In cases where you can't get 3-phase service, these are sometimes a good alternative.

For your building, there are a number of ways to figure out what you have now.

First... you could always ask an electrician. You might have to pay for that, though he can tell you in about 2 minutes or less.

The power company is also a good choice. 3 phase is a specific kind of service which has its own way of measurement and billing. The power company will be able to tell you what they're feeding your building without any question.

Are the transformers that power your building on a pole (not in a box on the ground)? If you have only one up there, you're single phase. 3 phase can be provided from 2 or 3 transformers, but not from one.

Look at your bill. If it says anything about a peak "demand charge", you're paying for 3 phase service. Not all utilities have this charge though. It's based on the largest load you place on the lines at any one time during the billing period. Think of it this way. If you turn everything on at once and draw 400 amps, yet your normal usage is 200, the power company has to plan their local grid to always provide the full 400, along with everything else in the area. If your meter says you tend to do this, they'll charge you for that capacity, which is where the "demand" term comes in.

Take a look at your power meter. Somewhere on the face, it will say whether it's watching 2 or 3 wires. If it's 3-wire, then you have a 3 phase service. Most home and small business meters will be 2-wire, which is single phase.

You can also check your breaker boxes. You'll mostly have small switches and a few larger ones. The larger breakers may have two switch handles tied together by a metal rod, but not always. In any case though, these ones are usually double the size. Those will be for things like your hot water, a residential stove, your lamphouse power, and maybe your furnace, popcorn and ice machines. All of that is single-phase stuff.

If you have even larger switches... ones that take 3 times the space in your breaker box as an outlet or lighting circuit, then you probably have 3 phase in your building. Those breakers would handle the largest of your loads... things like electric furnaces, large auditorium fans and restaurant-level cooking equipment. They would also handle larger lamphouses, though from what you say, it doesn't sound like you have that.

If you don't have it now, will you NEED 3-phase? That's something to consider once you've added up all the equipment you have now, then think about what you're likely to need in the future. If you have a smaller building that's adequately lit, there's little expansion potential and you haven't maxed out your current wiring... maybe not. If you need more light, you're planning to add a lot of equipment, maybe air conditioning or live theatre with lots of lights, then you're probably where you need to sit down with someone who can map all this out and project your needs and how to meet them.

[This message has been edited by rodeojack (edited September 12, 2007).]

Thanks guys. I think I get it now.

If I understand correctly, three phase helps level out large loads to help minimize drops and spikes. The larger the load, the more significant such variations could be in the performance of the equipment and the entire service to the building.

I don't think I have 3 phase service to my building currently. I happened to be speaking with the building inspector today and he said he didn't think there was 3 phase service anywhere in that area. I thought there might be, but now it seems there isn't.

I now feel more comfortable with the fact that I will probably have to go with single phase. I think my larger lamphouse will be a 2k and illuminate an approximately 11x25 screen. The other will be smaller, so it shouldn't be an issue either.

I am planning to include some cooking equipment in the building, but they are more akin to concession equipment than big restaurant level stuff. Expansion is unlikely, although the old store next door is for sale without any hurry to sell until the owners retire in 6 years. If I ever decide expansion in that direction makes sense, then I could absorb their electrical service to make the total larger.

The building already had air conditioning (even if it needs a lot of repair from sitting idol for a dozen years), and I'm not planning on live events (this just isn't the right facility for it).

I can't think of any other major additions to the electrical load except the addition of a second screen, but as I said it is not as large as the first. It will be tiny, really, with only a 7x13 screen. I'm figuring that it will need no more than a 750 watt lamphouse. Other power requirements in this second theater will be correspondingly low because of the small size. Hey, I couldn't make it any bigger without ruining the other theater. It will be about 13 feet wide with about a 30 foot throw. It will seat 35-40. I don't expect anyone to get excited about seeing films in such a small space, but at least I can offer newer films and more variety by adding the second screen.

Thanks again!

Sounds like you have it figured out!

One more thing: If you don't need to use 3-phase equipment but have your existing service maxed out, you can always have an additional single phase service wired into your place. Nothing says you have to have only one meter. At my drive-in I have 3 single services and wiring for two 3-phase services, though I only have one active now.

An older theatre in my area recently installed a new rooftop heat/ac unit that runs on 3-phase, though their building runs on single. They had a 3-phase meter installed just for that equipment.