I need to run a power for 18000 watt DJ equipment

[dbuckley]

Do not assume that an entertainment lighting load will ever be balanced - for two seconds at some point in a two hour show the balance may be perfect, but every other second it'll be unbalanced, and often wildly so. Lighting folk dont really care about phase balance as its an unrealistic expectation. As long as the supply is adequately rated for the load there are normally no problems.

 

[mivey]

I would not concentrate so much on the output figures quoted. I suspect there is some playing around with the power figures.

The power output of audio equipment is often exaggerated to make it sound bigger and better (add lots of grunts here). They often speak of the very brief (few cycles) peak output. This allows them to deliver very high output for very brief periods with relatively small equipment.

You may find the equipment peak output figures to be 10 times (or more) higher than the actual input.

 

[zbang]

Lighting folk dont really care about phase balance as its an unrealistic expectation. As long as the supply is adequately rated for the load there are normally no problems.

Actually, I've found that the better folks do care about it, and will try to spread the load evenly. Doesn't matter much when everything's changing, but at least they don't wire everything onto a single leg. (It's hard to do that on modern dimmer racks, anyway.) BTW, I'm talking about the 100kw+ rigs, not a few par cans in a dive bar.

 

[zbang]

this is simple, he has a 50amp range cord, probably 3 wire..thats feeds his distribution box. every small time band in the world has one, this very common. these guys are figuring their watts from the secondary of their power amps. these run at 26 volts. dont be scared when he says 18kw. just run a 6/3 on a 50 amp breaker with a regular 3 wire range outlet. . he'll do the rest. .... if it turns out he does have a 4 wire plug ( rare) then you will already have the 6/3, just change the device. most of these guys have a 4 wire to 3 wire converter anyway.

So... I'm supposed to give him 120/240 on a 3-wire receptacle? Where's the EGC? Isn't that where we started with this mess. If the band's gear has a N-G bond in it, I'm not connecting it. (If, and it's a big if, they have a 3-wire plug and a separate EGC, I might hook it up if it otherwise looks OK.) As for putting a 4-wire rec. on a 3 wire cable.... t'ain't gonna happen, either.

Oh, 26 volts? A Crest CPA900 amp (600 watt RMS/channel, 8 ohm) power amps is rated at max 82v RMS out.

 

[wireguru]

this is simple, he has a 50amp range cord, probably 3 wire..thats feeds his distribution box. Every small time band in the world has one, this very common. These guys are figuring their watts from the secondary of their power amps. These run at 26 volts. Dont be scared when he says 18kw. Just run a 6/3 on a 50 amp breaker with a regular 3 wire range outlet. . He'll do the rest. .... If it turns out he does have a 4 wire plug ( rare) then you will already have the 6/3, just change the device. Most of these guys have a 4 wire to 3 wire converter anyway.

what?!?!?!?!???????

 

[ultramegabob]

this is simple, he has a 50amp range cord, probably 3 wire..thats feeds his distribution box. every small time band in the world has one, this very common. these guys are figuring their watts from the secondary of their power amps. these run at 26 volts. dont be scared when he says 18kw. just run a 6/3 on a 50 amp breaker with a regular 3 wire range outlet. . he'll do the rest. .... if it turns out he does have a 4 wire plug ( rare) then you will already have the 6/3, just change the device. most of these guys have a 4 wire to 3 wire converter anyway.

if you read the original post, the customer wanted a 4 wire 50 amp recept fed with a 100 amp breaker. I told him I wouldnt install it that way, and that it was illegal and dangerous, he chose to just call someone else because I was too much of a hassle, now he has wasted his money on the install, and lost whatever profits he was going to make for the show because it got shut down. I have no clue how much equipment this guy runs, I have to go off of what the customer says they need, I have run power for shows that require a 200 amp 3phase disconnect for lighting, and a 100 amp single phase disconnect for amplification.... I will install whatever sized circuit a customer asks for, but it will have the correct breaker, wire size, and recept. etc....

 

[dbuckley]

BTW, I'm talking about the 100kw+ rigs, not a few par cans in a dive bar.

As am I. On a standard house or touring dimmer, the load will be spread across the phases, but not balanced.

The real fun is what do you do with strobes... they are horrible loads. When you're out in a field its fairly common to have a seperate genset for just the strobes, and then life is easy. On house power the supply better be damned stiff or voltage sags will cause all kinds of mayhem, like digital audio desks rebooting mid-show, never a good thing to have happen...