Power Needs

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Each light has an amperage rating. This can be found by the following:

Wattage/Voltage = Amperage [W/V=(A)] (Mean amperage, as it may change during use based on the light itself)

Most outlets are 15-20Amps. Here in FL, code now requires that they're 20AMP whether it's a commercial or residential application.

Never max out an outlet. Save a little bit of headroom.

*DO NOT pull amperage value from fuse rating.* You will be way off.
 
You dont need a formula, most outlets are 15 amps so that is how much you can draw. What you need to figure out is how much current your system draws.
 
Most home outlets are 15 amps and have what we all know as an Edison plug with 2 straight blades that look like this: ||
20 amp service is typically found in commercial buildings and the outlet allows for either a 15 amp plug or a 20 amp plug which looks like like this |- with one normal blade and one sideways blade. I don't have a character for a socket, but I think you know what one looks like.

Electrical codes seem to vary from state to state, county to county, town to town and inspector to inspector but I think the national code was changed about 20 years ago requiring all kitchen outlets to be 20 amp service to prevent a large toaster oven or microwave from overheating a 15 amp circuit. I think the national code also specifies that cellar and outdoor circuits are 20 amps. Whenever I do house parties I try to grab both an outdoor circuit and a kitchen circuit through a window.
 
Yup. It's called Ohm's Law. Do some research on it. Everything that has to do with electrical service is based on Ohm's Law. :)

I'd like to add a caveat ~ don't consider power amp output in watts as AC power requirement. The service requirement is actually much less.

If you'd like an idea of how much service you'll need, try maxing out your system at home on a standard 15 amp service. If the breaker holds, you'll be fine. If not, you'll need more.
 
No perfect answer for this as every place will be different. First you can only pull about 80% of the outlets total amps. So if it is a 20 amps, you can only get 16 amps before it will trip and about 12 amps on a 15 amp. You will also need to remember also if you use too small an power cord, that could raise your amp draw. One more thing is you never know what else may be on that same plug. Most of the time something else will be tied onto that same circuit.

But as Rick points out you will first need to know what the total amp draw is. I think the meter he is speaking of can be found at parts express.
 
SoftJock Rick said:
Spend the $20 for a Kill-A-Watt meter... :)

You can check each component individually, or all plugged in as one. It will give you amps, watts and VA of actually usage.
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This is good advise! Every DJ should have one in his/her toolbox along with a cable tester.
 
Fred Wright said:
Yup. It's called Ohm's Law. Do some research on it. Everything that has to do with electrical service is based on Ohm's Law. :)

I'd like to add a caveat ~ don't consider power amp output in watts as AC power requirement. The service requirement is actually much less.

If you'd like an idea of how much service you'll need, try maxing out your system at home on a standard 15 amp service. If the neighbors don't complain, you'll be fine. If not, you'll need more.
Click to expand...
There I fixed that for ya!
 
prodjay said:
No perfect answer for this as every place will be different. First you can only pull about 80% of the outlets total amps. So if it is a 20 amps, you can only get 16 amps before it will trip and about 12 amps on a 15 amp. You will also need to remember also if you use too small an power cord, that could raise your amp draw. One more thing is you never know what else may be on that same plug. Most of the time something else will be tied onto that same circuit.
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That 80% load recommendation is continuous load. A musical amplifier is (typically) not a continuous load. Other than EDM with extended bass, most music runs at a rather low amperage draw with very short bursts of high current, in fact you should be able to easily pull full power and possibly a little more from a circuit breaker for very short periods of time. A kill-a-watt will show you the numbers.
 
Rule of thumb for me always use a kilowatt meter before the show starts (Lowes stocks them). If you frequent the same hall make a notebook for what outlets are separate from each other. I had an issue back about 10 years ago and shared the beer cooler on the opposite wall...didn't work out. I usually try to have 2 circuits at all times for small setup, just in case. Old school Crown CE2000 amp and EV Eliminators (mains or subs) needed 10 amps per pair when I used them. Now with powered speakers (way more efficient) can pull about 12-13 amps when using 2 subs and 2 mains when turned up pretty loud. LED lighting has helped a ton too...barely 1 amp for most of what I use. When I use a moving head fixture I will grab another circuit. I usually go for the 220AC and split it myself just to be safe for the bigger shows.


I have a Furman surge protector mounted in my rack for each circuit that I use that monitors voltage and current draw...very helpful and you can see where you are at while performing.
 
prodjay said:
No perfect answer for this as every place will be different. First you can only pull about 80% of the outlets total amps. So if it is a 20 amps, you can only get 16 amps before it will trip and about 12 amps on a 15 amp. You will also need to remember also if you use too small an power cord, that could raise your amp draw. One more thing is you never know what else may be on that same plug. Most of the time something else will be tied onto that same circuit.

But as Rick points out you will first need to know what the total amp draw is. I think the meter he is speaking of can be found at parts express.
Click to expand...

ProDJ is correct about using too small a cord, but for the wrong reason. Smaller wire size cords = increased resistance = meltdown. Then again if it melted untill the insulation was gone and the wires shorted you would have increased current for a second :)
 
Ron said:
Anyone have a good formula for determining how much you can pull from a single outlet for your gear?
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You would need total input current for all your gear. NEC assumes 80% continuous load. 12 amp load for 15 amp ckt. 16amp load for 20 amp ckt.
 
Follow up note... certain amplifiers, like QSC Powerlites, and QSC PLX series will only use the amount of power it is capable of obtaining from the line. You'll be ok, but your sound will suffer, not enough of a "pipelne" available at times. But, they are designed not to pop a circuit. The bass will sound shallower, etc... I personally luv it when I have a power distro header, or a clean 20 or 30 amp circuit... the QSC 3402's just hummm along putting out bass to our subs.

Also, lighting draws a lot of power. Speaking of non LED stuff that is professional... not "spin and pukes" etc... so always go separate circuits for sound and lighting. Final comment, beyond Furman's etc... find out your biggest power draw on the lighting side. After you are set up and operational... turn those lights on, and monitor your Furman's. If they move a few volts or amps... you are on the same circuit as your sound... it's the last ditch, pure tell tale answer to find separate circuits.
 
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