Powering lighting in a non-theater space.

We are putting a show into a former IMAX movie theater and will have a deck with truss to hang lights. Our power will come from the front stage area and we need to use the existing outlets located there for power.

What size or type of cable will be appropriate to run up to 70 feet of power to our truss? Is there a recommended supplier for these power cables?

We want to be prepared for the load-in with enough cables ready. We have 12 led slimpars, 4 Rogue R2, 6 Q-Wash 560Z, 8 Martin MX-4, and 7 Martin 300 wash.

Thanks for the help.

So, a few things.

1) You should hire an entertainment electrician. This is their job. I know this seems like an unhelpful suggestion, but someone on site with experience and more information can better design the electrical system you need.
2) What are your power needs? What wattage is each fixture? How many fixtures can you daisy-chain power through?
3) How many individual circuits (not outlets) are available? What's the breaker rating on each circuit? (It should be 20A in the US, but check.)
4) For 20A circuits, you need 12-gauge 3-conductor cable with appropriate connectors on each end. While you can build these, if they're not done correctly, they can be dangerous. I would rent from an area entertainment or event company like 4Wall or High Output. Search around for whomever is in your area.

I'm really not trying to be harsh. Electricity is dangerous stuff, and it's better to have someone on hand who has some experience. It will also save you some time and headache if you need to troubleshoot your system.

If you say *former* IMAX theatre, i'm not even sure the circuits would be 20A, they're probably only 15A. Which means your continuous load per circuit should only be 1500W.

If you do get an entertainment electrician, I'd take a look at the former projection room. Assuming that old IMAX projector was powered at 120v or 203v, there might be a high current tie in an electrician can either adapt or plug a distribution (distro) box into.

EdSavoie said:

If you say *former* IMAX theatre, i'm not even sure the circuits would be 20A, they're probably only 15A. Which means your continuous load per circuit should only be 1500W.

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That would be MAX continous load. The 20% derate for continous load would only be 1440 Watts.

Rent a gennie and bring power from outside.

EdSavoie said:

If you say *former* IMAX theatre, i'm not even sure the circuits would be 20A, they're probably only 15A. Which means your continuous load per circuit should only be 1500W.

If you do get an entertainment electrician, I'd take a look at the former projection room. Assuming that old IMAX projector was powered at 120v or 203v, there might be a high current tie in an electrician can either adapt or plug a distribution (distro) box into.

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If it was true 15/70 IMAX, the projection booth will have power, but you will need a real electrician to get at it. An old school small 35mm setup I ran in college used 20A 3ph for a 2KW lamp and had a 1/4 horse motor driving the projector itself, plus 20A circuits for the sound system and amps. Except for the sound gear, everything was hard wired to the breaker panel. If I remember back to my summers in a commercial multiplex 20 years ago, the same held true about the projectors being hard wired in. Some of the biggest old school 15/70 IMAX lamps were 15KW according to wikipedia (https://en.wikipedia.org/wiki/IMAX#Projectors).

Getting back to the original topic at hand, the only size/type of cable for power is either socapex or 12/3 SO.

Van said:

Rent a gennie and bring power from outside.

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That's kinda hard, as I'm pretty sure the venue in question is in the middle of a pyramid. Originally built as a quasi-ride, it's been called the worst IMAX theatre ever built.

cbach said:

What size or type of cable will be appropriate to run up to 70 feet of power to our truss? Is there a recommended supplier for these power cables?

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Call PRG or 4Wall. Ask for help from the house electrician(s).

I find most convenience receptacles in commercial buildings are 20 amp, but they could be 15. Is the event likely to be near "continous" electrically - 3 he at full IIRC .

jonliles said:

That would be MAX continous load. The 20% derate for continous load would only be 1440 Watts.

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Sorry, you are indeed correct. I had pulled the number out of my head for a 125v 15A circuit.

BillConnerFASTC said:

I find most convenience receptacles in commercial buildings are 20 amp, but they could be 15. Is the event likely to be near "continous" electrically - 3 he at full IIRC .

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As a wise @RonHebbard pointed out to me, I was applying my amperage guess based on my personal experience north of the border, where I find 15A commercial circuits just as, if not more often than 20A ones!