Current Draw for Gear/lights

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S

Steve LeBlanc

Mac Daddy DJ
Aug 19, 2006
6,829
192
65
Fredericton, NB
www.frederictonweddingdj.com
So I have a University House social this Saturday. I'm renting 2 LS800 subs and going with my regular set up.....plus a couple of extra lights. I had asked the university for 3 separate circuits to be safe...
They have come back and said that the facilities people can give me enough juice from one circuit (new hall)...They want to know how much I need
So heres the set up

2 FBT Maxx 6A's
console case w/ mixer, wireless mic, laptop, rack pc
4 LED pars, Chauvet Kinta, Oceana, and 2 Chauvet Shooting Stars, 2 starballs..

normally I have no issues with one circuit with all this....I assume I'm pulling less than 7 or 8 amps...

So the extras are:

2 LS800 subs (powered)
2 Martin Destroyers
perhaps 2 scanners


I am more than good if they can give me 30 amps through a 120 plug?

Thanks in advance.......
 
Well... yes and no. If they can give you 30 amps you should be fine. I assume your system has 15 amp plugs on it... or maybe 20 amp? If you need help distinguising between the two I'd be happy to help there.

There's a quick way to figure your approximate amperage draw. There are some variables (power factor, etc... but for the sake of easy math we'll assume that the PF is unity or "1"). It's basically Ohm's Law.

First we should define the terms we’ll use:

Amperes (I)– a unit of measure for the current or flow of a circuit

Voltage (E)– the difference of potential in a circuit, or the “pressure” behind the electricity

Power – the measure of “work” accomplished in a circuit. Power is measured by Watts and Volt-Amperes.

Volt-Amperes (VA or P) – also called “Apparent Power”. This is the sum of volts x amps.

Watts (P)– also called “Real Power”. This is the sum of the current squared x the resistance.

E = I x R (Ohm’s Law)

P = I2 x R

VA = E x I (Watt’s Law)

Therefore your Voltage (E) we'll assume is 115 the amperage is unknown, but we know the wattage approximately. We'll use the Oceana as an example where P = 800. In a Unity power factor VA = P.

So our equation will stack up like this 800 = 115 X I So we need to solve for I. 800 / 115 = I So your amperage on an Oceana is 6.96. So that fixture alone is drawing nearly 7 amps. Many fixtures and devices will have the anticipated current draw (Amps) listed. You can just add them up, and solve for those that don't indicate it. Your equipment may not draw it's listed draw because you may not be running it at it's full potential, but if you plan for it you won't have any problems.

I hope this helped.

Ben
 
:sqconfused:

Sort of...

The Oceana does have a 7 amp fuse, as does the Kinta...so i guess that tells me something there..Total Draw 14 amps..

So I've run these in my house with my console and speakers and haven't blown a fuse?

The LED Pars are 30w..am I correct that they draw about a third of an amp each?

The LS800's according to their website draw 8 amps each....16 amps total

I looked at the backs of my FBT's. There's a sticker with 6.3 A om it...could that be the draw?

I add all this up and get 42 amps...so give or take 50 amps.....

Huh?

and Ben...I'm assuming 15 amp plugs...They look normal......How do you tell?

Seems like a lot of juice....
 
Your system is likely not drawing it's full potential, and fuses are basically the last line of defense before a failure. We electrical geeks call them "overcurrent protection devices". It's unlikely that you were running your system at full power with both the Kinta and Oceana on at the same time. So your system was likely drawing less than 6 amps, keeping the total under 20. Another thing to know about circuit breakers... they are typically triggered thermally. So they can warm up over time, while allowing in excess of their rated power for a little while, but once hot they will trip faster if you repeatedly offend them.

A good example of a system's "potential" draw and "real" draw would be a system we did for a gymnasium. The three power amps have a "potential" draw of 36 amps combined, however we have them running on a 20 amp circuit. When we calibrated the limiters in the DSP for the system we connected an ammeter and found that at the greatest anticipated use of the system, it was only drawing 16 amps, and under typical use about 13.

A 15 amp plug is a "typical" household outlet with two vertical lines and a grounding plug. A 20 amp plug has one horizontal line, one vertical line and a grounding plug. Many times a 20 amp receptacle will have the horizontal and vertical conductor as a "T" so that it can accept both 15 amp and 20 amp plugs, since a 20 amp circuit will handle 15 amps, but a 15 amp receptacle will not accept a 20 amp plug.

Ben

thatmusicguy said:
:sqconfused:

Sort of...

The Oceana does have a 7 amp fuse, as does the Kinta...so i guess that tells me something there..Total Draw 14 amps..

So I've run these in my house with my console and speakers and haven't blown a fuse?

The LED Pars are 30w..am I correct that they draw about a third of an amp each?

The LS800's according to their website draw 8 amps each....16 amps total

I looked at the backs of my FBT's. There's a sticker with 6.3 A om it...could that be the draw?

I add all this up and get 42 amps...so give or take 50 amps.....

Huh?

and Ben...I'm assuming 15 amp plugs...They look normal......How do you tell?

Seems like a lot of juice....
Click to expand...
 
30 amps at 120 volts should be plenty of power, but they or you will need to break that 30 amp circuit out into 15 amp edisons in order to use it safely. I would assume that they will provide a breakout box / distribution, but even if they do you need to carry enough cords to run separate circuits to the distro.

I wouldn't want to run all that on a single 15 amp rated plug. The distro would divide the load for you.
 
I did a wedding awhile back where the room had a 50amp breaker for all the wall plugs... turn that one breaker off and the whole thing shut down...

I've always used the 100 watt = 1 amp method just to be easy and safe,,, overkill but I've rarely blown a circuit...
 
I'm getting it. All my plugs are 15 amp plugs.
I presume that the university can deliver more than 15 amps to each outlet in the room. They are telling me I won't need to go outside the room,so I presume they'll give me two or 3 outlets at 20 amps per.....
My thought is to tun the two Ls800's to one and the remainders to the others.......

Thanks all
 
or if three run lights on one sub on the other and system and tops to the other. You end up with a core system regardless of one of the others blowing a fuze.
 
Is there an easier way to tell if two outlets are on the same circuit than flipping through the mis-(or un-)labeled panels and turning off half the building before finding the outlet(s) in question?

Just wondering how others' deal with this annoyance.
 
Unless things are very different in Canada the maximum current allowed on standard outlet is 20 amperes. That is the maximum current for a branch circuit serving receptacles as well. In older construction the branch circuit may be breakered or fused at 15 amperes.

The typical receptacle (itself) is rated at 15 amperes. The 20 ampere receptacles have a small notch perpendicular to one prong's blade.

If you are using the older type amps with big filter caps and a standard linear supply, if the amps are turned on simultaneously, the inrush current when turned on should be your worse case situation. If you are using newer amps with switching type supplies the case is different.

Don't forget to that the breaker does not trip immediately upon exceeding the rated ampacity. If drawing only 15 or 20 percent more the circuit might not trip for hours. At 100 percent over the rating you might only have a couple of minutes or less.
 
The answer may be as close as Home Depot or Lowes

awdj said:
Is there an easier way to tell if two outlets are on the same circuit than flipping through the mis-(or un-)labeled panels and turning off half the building before finding the outlet(s) in question?

Just wondering how others' deal with this annoyance.
Click to expand...

There are devices that you can plug into an outlet that will place a signal on the line (branch circuit). A pickup device can read the tone placed by the sender. This is one example:

http://www.mygreenlee.com/products/det.cfm?id=3229&upc=07578
 
I just wanted to clarify what Balanced Line is saying. A branch circuit is the wiring between the final OCPD (breaker) and the receptacle (outlet). 20 amps is not the maximum branch circuit rating for supplying a receptacle, it is the maximum branch circuit rating for supplying a 15 or 20 amp receptacle. Receptacles come in all sorts of voltage and amperate ratings. So if you have a distro, as Audiopyle was stating, you can use much higher rated receptacles and distribute them down into smaller circuits.

The breakdown is as follows (NEC 2005, Table 210.21(B)(2)) for maximum Cord and Plug loads connected to a receptacle:

Circuit Rating Receptacle Rating
15 Not more than 15
20 15 or 20
30 30
40 40 or 50
50 50

Bear in mind though that there are supply conductor requirements for these larger loads. For a 15A BC it is 14 AWG, for a 50A it is 6 AWG. For the complete breakdown, please reference table 210.24 in the 2005 NEC.

Ben
 
Clarifying the clarification

Woah Ben, there have to be eyes swimming around here! I have not checked what Ben has said and given the reference I’d wager money that he has so Ben thank you for the research. It’s great to have you and it is wonderful to have someone doing research.

When you exceed 20 amps the circuit must be dedicated to a single load. A range cook top or freestanding range or electric clothes dryer or similar load that typically draws and is breakered at more than 20 amperes (and often uses a cord set) must be a single dedicated circuit. One breaker will be connected to one receptacle. Unless Canada has different regulations, a standard receptacle outlet will always be breakered at 20 amps or possibly 15 in the case of older installations.

I’m sure Ben knew what is stated here but may have not realized how it read. As mobil DJ’s you should not ever encounter a circuit breakered (or fused) at more than 20 amps. The problem is that anyone plugging in some light duty device such as a table lamp into a high amperage circuit still expects the circuit to be protected. The lighter gauge wiring associated with that type of plug and receptacle may not draw sufficient current to pop (trip) a large breaker.

Each high ampacity circuit has a specific type of receptacle and circuit associated with it. When an installation is wired to code, if you can plug your equipment into it, you will be protected in an over current situation using the device made for it.

I hope this helps more than it confuses. - Big cord sets that draw more than 20 amps exist but you ain’t gonna plug into it cause your plug will not fit in da hole unless it was made for it.

- Bob
 
Color me embarrased. LOL. Sorry to get off on the deep end. I'm a true geek I guess. It wasn't much research... I've been accused of having the NEC memorized. We do so much contracting and system design that I'm constantly referencing it. I'll try to "keep it simple" from here on in. ;)

Incidentally... if there are jocks with large format shows that are encountering difficulty with this subject, there are some really simple solutions to your problem. Devices like the Furman ACD-100 will allow you to use a variety (had to restrain myself from being specific LOL) of input voltages, phases and amperages to acheive a standard 120V output of 5 x 20 amp receptacles. 100 amps should run just about any DJ show on the planet. ;)

Ben
 
As Northern Light FX and audiopyle were pointing out there are portable distribution panels that can be used to hook up to those heavier ampacity outlets. If you have purchased or are already using one you know the drill. For those not familiar with their use and the less technically savy understand you cannot use those big honkin' outlets just by getting a big cord.

If using a portable distribution panel, get someone to break you in on its use and safety features. This is especially true if 15 amp edisons or OCPD sounds like Greek to you.
 
Forgive me...

The Vinyl Spinner said:
I'm sorry if I missed it, for I skimmed, but, to my knowledge, the standard household circuit in Canada is 15 amps.
Click to expand...
Johnny, did you mean "Forgive me father for I have skimmed."? To the best of knowledge, this isn't a mortal sin unless you do it against the mob.
 
Balanced Line said:
As Northern Light FX and audiopyle were pointing out there are portable distribution panels that can be used to hook up to those heavier ampacity outlets. If you have purchased or are already using one you know the drill. For those not familiar with their use and the less technically savy understand you cannot use those big honkin' outlets just by getting a big cord.

If using a portable distribution panel, get someone to break you in on its use and safety features. This is especially true if 15 amp edisons or OCPD sounds like Greek to you.
Click to expand...

Greek sounds easy compared to that. I really like the idea of the ACD-100 distro. Looks like a very usable piece of stuff. But how do you go about hooking it up? Is it something I have to hard wire into the circuit box or what?
 
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