Power Feeder and Voltage Drop

Re: Power Feeder and Voltage Drop

Chris Delcambre said:
Yessir I am using the vsx for processing... At what distance was your FOH???
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Typically 100-125', I would not use an amp bigger than a Pro 5200 on those ribbons. Bigger amps on the subs might be a plus, but you might consider upgrading to Versarray 218's. We are running 8 now at only 2200 watts per box and I always have PLENTY of low end! The SRX will go lower, but I would bet that the VR218's are louder at "actual audio" frequencies.
 
Re: Power Feeder and Voltage Drop

200 Amps is plenty for most stuff these days. #2 banded is rated for 190 amps. It's what I use. I use a 200 Amp OCPD and inspectors have always been good with it. (Just dont pull over 190 Amps) If you need bigger wire, say 2/0 or 4/0 for a bigger show, let the generator provider bring the cable. That being said, you won't need the big wire unless you get a totally different rig and lots of it.

Next weekend I will be providing six 3-way tops a side, 20 subs, 12 monitor mixes, sidefills, 16 movers, some LED pars, consoles, stage power, etc. we will be running on #2 five wire. We will have plenty of extra capacity for safety margin. If I get a break, I'll measure current at full output and post it here. I am assuming somewhere around 100 amps.
 
Re: Power Feeder and Voltage Drop

Those cable current ratings are for continuous power. In this case, 'continuous' means 3 hours. So in a lighting circuit it could be a factor, but nobody runs full volume test tones for 3 hours.
 
Re: Power Feeder and Voltage Drop

Chris Delcambre said:
Thanks Silas... Does that #1 run your vertec rig I see in your pictures and all your lighting or do you have a seperate light distro???

Chris
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I don't own the Vertec rig, unfortunately.

The 200 amp 3 phase distro has always been enough power for everything I've done. I've never seen more than 100 amps continuous on any leg unless I was using my former 40k conventional rig at 100%, or if I was using my strobes.
 
Re: Power Feeder and Voltage Drop

Well Guys I thank you for all of your responses... I have ordered the new distro...

Its going to be 100ft #2 feeder to amprack 1 and 50ft #2 feeder from amprack 1 to amprack 2. Each amp rack will have 15- 20AEdison Circuits and a L14-30A circuit for my monitor rack packs... Should be good to go on power for a while...

Jim at the AmpShop.com was a huge help in getting it designed to meet my exact needs...

Thanks again.
Chris
 
Re: Power Feeder and Voltage Drop

Upgrading the power distro to reduce voltage sag is good but unless the lack of performance you noticed was due to premature clipping, you won't improve the amps' performance.

It's an oddly common misconception that mains voltage controls a power amp's gain--and therefore the loudness. Mains voltage does directly influence the supply rail voltages in most power amps, and therefore the voltage at which the amp clips. IOW, voltage sag will cut into headroom but unless it's so bad that it causes the amp to shut down or otherwise behave strangely, it won't affect the amp outputs.

I concur with those who have suggested that the likely core issue is insufficient "rig for the gig" and resulting power compression.
 
Re: Power Feeder and Voltage Drop

Silas Pradetto said:
You should refer to NEC400 for ampacity of free-air feeder cable. Common sizes are:

#2 AWG 190 amps
#1 AWG 220 amps
#2/0 AWG 300 amps
#4/0 AWG 400 amps

I use #1

Especially consider that you CANNOT band feeder cable as it will require derating. Also know that 2/5 SOOW cord has WAY less current capacity than free-air #2 due to derating as well.
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You can band feeder with no derating as long as there are not more than 3 conductors in a bundle (2 current carrying). 2 hots, neutral and ground would need to be derated.

We band all of our feeder in a set of 3 and a set of 2.

We have no problem with running 2/O banded this way, 4/O is a whole different deal.

db
 
Re: Power Feeder and Voltage Drop

RYAN LOUDMUSIC JENKINS said:
200 Amps is plenty for most stuff these days. #2 banded is rated for 190 amps. It's what I use. I use a 200 Amp OCPD and inspectors have always been good with it. (Just dont pull over 190 Amps) If you need bigger wire, say 2/0 or 4/0 for a bigger show, let the generator provider bring the cable. That being said, you won't need the big wire unless you get a totally different rig and lots of it.

Next weekend I will be providing six 3-way tops a side, 20 subs, 12 monitor mixes, sidefills, 16 movers, some LED pars, consoles, stage power, etc. we will be running on #2 five wire. We will have plenty of extra capacity for safety margin. If I get a break, I'll measure current at full output and post it here. I am assuming somewhere around 100 amps.
Click to expand...

Did my show yesterday. During all of the openers I was running typically 24-31 amps per leg of three phase. During peaks I would get 40-45 per leg. These measurements were for audio only. we put lighting on another generator and he was averaging 8-9 amps per leg except while the atomic 3000s were going. During the last song of the headliner it to waaaaayyyyyy too loud with intense bass. I was not at the generator to check the current at that moment. This show was a hip hop show with national artists and at the busiest time we had 10,000 to 12,000 people in front of the stage.
 
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