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Are two 20 amp circuits enough?

jakelly

jakelly

Nov 8, 2009
582
27
#1
We have a gig coming up on the 17th of Sept., an outside gig. There are only two 20 amp circuits close by for the band to use. We are a five-piece with a medium-sized PA, but we will need to run at least some lights since we will be playing 'til around 11PM.

I'm wondering if you all think we will have to rent a generator or will two 20 amp circuits be enough? Should we find an alternative way to hook up lights, or?

Thanks a lot!
 
#2
missing data. How much power does the "medium sized" PA draw? How much power does the the lighting need? Ballpark estimates work here---(i.e.: PA draws 4 amps, lighting draws 10 amps, bass,guit, keyboard amplifiers draw 8 amps combined, etc).

Stabbing in the dark, i would say TWO 20-amp circuits would be probably be close to twice of what is necessary. But its good to be thinking of that in advance. Just need to find the numbers ( I = P/E). Current(amps) = Power(watts) divided by Voltage
 
#3
jakelly said:
We have a gig coming up on the 17th of Sept., an outside gig. There are only two 20 amp circuits close by for the band to use. We are a five-piece with a medium-sized PA, but we will need to run at least some lights since we will be playing 'til around 11PM.

I'm wondering if you all think we will have to rent a generator or will two 20 amp circuits be enough? Should we find an alternative way to hook up lights, or?

Thanks a lot!
Click to expand...

If your lights are the typical halogen lamp type, no way along with a PA. Modern LED Pars, sure. But really you need to total the amount of amps you draw with the equipment you intend to use.

If it's insufficient, see if they have a 220 circuit. See if you know any electricians who can rig up a 220 panel for you (with it's own 110 outlets on a circuit breaker) with many different 220 coupling adapters. Something like that comes in handy at outdoor gigs.

Generator would have to be pretty darn big to be of any use with continuous power.

I'd be comfortable with two 20 amp circuits if it was just guitar and bass amps, a couple of lights (or a slew of LED ones) and a very small PA. Check what you draw.
 
#4
Sundogue said:
If it's insufficient, see if they have a 220 circuit. See if you know any electricians who can rig up a 220 panel for you (with it's own 110 outlets on a circuit breaker) with many different 220 coupling adapters.
Click to expand...

That won't work on most 220v circuits. Most have black and red feeds but no neutral. You can't create a 110v outlet without a neutral.
 
#5
by "medium-sized PA", what exactly do you mean?

my 4-pc rock band has a "van-sized" PA; two yorkie E15 tops, 4 LS608 subs, a 2800-watt QSC PL4 power amp for lows and a 2000w PL2 for highs. (IEMs spare us from lugging monitor wedges and amps, yay.) along with a 1500w bass power amp, a 100w tube guitar amp, and a bunch of LED lights, we can play anywhere with one 20-amp circuit. two is luxury, where we put the subs amp on its own circuit and the rest on the other.
 
#6
Thanks for the replies! I have no numbers yet, as to current draw but...

By "medium-sized PA" I mean two powered subs, 4 powered monitors, two passive mains (mains powered by 600 watts - but we may actually get a bigger power amp by showtime).

Maybe what I call "medium-sized" is actually a small PA.

But walterw, if its possible to power your system with one 20 amp circuit, we should be fine, depending on the lighting.
 
#7
If everyone is using tube amps and you are using standard PAR cans and not LED's no.

PAR cans suck the life out of a breaker box.

We have run an entire band off of 20 amps.

Roland digital kit plus monitor amp, Micro VR, Marshall half stack, lights (LED), board, Crown XTI 2000, XTI 4000 misc rack effects etc with no issue. That's just on one 20 amp circuit.
 
#8
Without more info, a good answer is difficult, but I'll try.

Make sure the bass amp and PA (especially if you have subs) are on separate circuits.

Distribute the other stuff equally on each circuit---keys on one circuit, guit on the other.

The lights become a problem. One 300 watt on each circuit might be ok. If you want to be a bit more certain, rent a generator for the lights only. If the lights are "starved for power" they'll just illuminate less. Amplifiers won't operate as well on the generator unless it is fairly large (8000 + watts), and its out put is "clean".
 
#9
calculated like this 20 amp x 120 volts = 2400 watts
then 80 percent (80 percent is a code thing) of the 2400 which leaves you 1920 watts per circuit ( you can stretch the watts a bit over 80 percent but tripping a breaker is not far off)
Add up your lights which will be your biggest load if the can squeeze onto one circuit you might make it
Keep in mind the watt rating on amps is peak so if your running your amp a half the volume you won't be drawing the peak rating
On the other hand the lights need to be rated at full wattage
 
#11
Rick Auricchio said:
That won't work on most 220v circuits. Most have black and red feeds but no neutral. You can't create a 110v outlet without a neutral.
Click to expand...

It will on most 220 Vac plugs & tap-ins I've encountered. Older ones & ones for welding machines might delete the neutral.

But 20 A sounds like two 110 volt connections. If using dimmers I'd worry if they are on the same phase; electrical noise carry-over.
 
#12
Rick Auricchio said:
That won't work on most 220v circuits. Most have black and red feeds but no neutral. You can't create a 110v outlet without a neutral.
Click to expand...

We had an electrician make up a circuit box with 110 outlets and separate circuit breakers for each. Then the main connector on it has multiple 220 adapters to fit into just about any type of 220 outlet.

That has saved our butt on many an occasion where they had insufficient 110 outlets. Of course that depends on whether they actually have any 220 outlets. Most outdoor gigs have food vendors that utilize 220, so there is almost always a power feed on those gigs. And most bars that serve food have 220 we can tap into as well.

We've even convinced some places we play at to have an electrician put a 220 connection in onstage.
 
#13
Sundogue said:
We had an electrician make up a circuit box with 110 outlets and separate circuit breakers for each. Then the main connector on it has multiple 220 adapters to fit into just about any type of 220 outlet.

That has saved our butt on many an occasion where they had insufficient 110 outlets. Of course that depends on whether they actually have any 220 outlets. Most outdoor gigs have food vendors that utilize 220, so there is almost always a power feed on those gigs. And most bars that serve food have 220 we can tap into as well.

We've even convinced some places we play at to have an electrician put a 220 connection in onstage.
Click to expand...

The only way to get 110 volts safely is to have a neutral conductor (like the other guy said)
If you plug into a 3 wire plug you will be using the ground conductor to carry current and while it will work it doesn't give you anyway to safely open a circuit breaker in the event of a fault to any off your equipment and thus will likely burn up a bunch of stuff
Make sure you have 4 conductors
2-hots black /red
1 white Neutral
and one ground either green or bare
No other way is safe
 
#15
Two 20 amp circuits isn't ideal, but I've done it plenty. We were running 6 par cans and 6 LED cans. PA was about 3000 watts total (mains, subs and monitors), 500 watt bass amp, 60 watt guitar amp. we just kept the lights on one circuit and everything else on the other. Worst case scenario the lights will trip the breaker a few times, but the other circuit should be fine.
 
#16
cashpoor51 said:
The only way to get 110 volts safely is to have a neutral conductor (like the other guy said)
If you plug into a 3 wire plug you will be using the ground conductor to carry current and while it will work it doesn't give you anyway to safely open a circuit breaker in the event of a fault to any off your equipment and thus will likely burn up a bunch of stuff
Make sure you have 4 conductors
2-hots black /red
1 white Neutral
and one ground either green or bare
No other way is safe
Click to expand...

Not sure what the electrician did. All I know is we have a 110 breaker box on a cart with 100 ft. of some heavy ass cable with a 220 connector, and a ton of adapters.

We've been tapping into 220 at places with this for 20 years with no problems at all. It's been upgraded a few times during that span.
 
#17
I'll Be the first to note that you contract should read "2 ea 20 amp --- OR 3 ea 30 amp clean power supply via 12 awg lines --- these extension cords must notbe orange in color"

I wouldn't let my band take liability for bad power or jerri-rigging something that may negate liability insurance or create Ill will
 
#18
MNAirHead said:
I'll Be the first to note that you contract should read "2 ea 20 amp --- OR 3 ea 30 amp clean power supply via 12 awg lines --- these extension cords must notbe orange in color"

I wouldn't let my band take liability for bad power or jerri-rigging something that may negate liability insurance or create Ill will
Click to expand...

Oh yea. Supplied 110 115 not 220
 
#19
jakelly said:
We have a gig coming up on the 17th of Sept., an outside gig. There are only two 20 amp circuits close by for the band to use. We are a five-piece with a medium-sized PA, but we will need to run at least some lights since we will be playing 'til around 11PM.

I'm wondering if you all think we will have to rent a generator or will two 20 amp circuits be enough? Should we find an alternative way to hook up lights, or?

Thanks a lot!
Click to expand...

You'll be fine. Divide it up on the AC line rating of each device as best you can.

I've done 2 guitars (100w tube heads), 3 x Behringer EP2500, 16 100w par cans, and a 1400 watt bass head on 2 x 15A circuits without an issue.

All we had to do was setup the lights with a max of 8 'on' at any one time (10 was possible, but a margin of safety is always a good thing).. easy as cake with a good set of dimmer packs and a good DMX lighting controller :) We got away with 4 lights on constant and the rest on an audio pattern.

We also did a lower volume gig once with the same PA, 8 100w pars, a single 25w guitar head and my RH236. All on the same 12 ga 50' extension cord going to one 15A outlet.. Not a single problem in 4 hours.
 

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