1. Register NOW and become part of this fantastic knowledge base forum! This message will go away once you have registered.

How much equipment per circuit breaker

Discussion in 'Pro Audio Equipment' started by Scott_Fouts, Jun 19, 2003.

  1. Scott_Fouts

    Scott_Fouts Guest

    I've been wondering how close I'm getting to tripping a circuit breaker. Do most of you run your equipment on one circuit, or are you upgrading to a 20 amp? Or . . . are you using more than one circuit?

    How do you calculate when its time to look for more power?

    -Scott
     
  2. Davedog

    Davedog Distinguished Member

    Joined:
    Dec 10, 2001
    Location:
    Pacific NW
    You would have to be drawing a continuous current of over 15 amps to trip a 15 amp breaker.Recording equipment,computers,electronic instruments, and such do not normally display a spike in current draw even when theres a lot going on.Large tube type guitar and bass amps are another thing though with a large output transformer there is a buffering of the current draw.
    I dont know what youre running in your setup but chances are unless you are running a large console and several racks of outboard tube gear you're probably safe.
     
  3. jslator

    jslator Guest

    Or maybe a couple of clothes irons. They draw big current. Recording gear generally doesn't.
     
  4. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    Scott - all of the equipment you use should indicate the actually power you will consume during use........ add it all up and see where you are.

    Today's equipment does not use a whole lot of power - so 15 amps goes quite a ways......

    If you do find the need to expand and pull another circuit in - i would suggest trying to make sure it's from the same leg of your power supply as the one you're using now - i have seen some weird things happen with ground loops when it isn't.

    Good luck and Happy Hunting

    Rod
     
  5. Ron.G

    Ron.G Active Member

    Joined:
    Apr 24, 2003
    Also check to see what else is on that circuit. If your in a house, chances are good that you have other household things on that circuit.

    If the house is some what new at least you won't be sharing a circut with the refrigerator or other appliances. Probably sharing a adjacent room's outlets.

    If you know a electrician, he could put a amp meter on the wire leading to that circuit breaker and tell you exactly what your drawing.
     
  6. Scott_Fouts

    Scott_Fouts Guest

    hey everyone - thanks for the responses.

    and -yes - i do use a clothes iron, but only for that cool efx smoothing when i need to compress the sound of the flourescent lights and the ceiling fan.

    thanks! i'll get an ampmeter from a friend. never thought of that!

    scott sends . . .
     
  7. Davedog

    Davedog Distinguished Member

    Joined:
    Dec 10, 2001
    Location:
    Pacific NW
    Remember, that when you clamp your meter onto this particular circuit that all your equipment will not only have to be on, but it'll have to be doing something. Gear at idle has very very little current draw.Mostly just for the lights and such. You would have to be in a very very old house to have a circuit that shares power with the kitchen, that is if youre in a bedroom or a basement.If you're in the dining room then the chances are greater.Also, in thinking of changing a circuit to a higher ampere setting on the breaker, this would mean running a new wire rather than just changing the breaker.Breakers protect the wire and a larger breaker on smaller wire is a condition that can lead to fire.
    I only say this stuff because in my 30 years of being an electrician I've seen all kinds of messes caused by stuff like this.And as Rod said, you'll want to be on the same phase in order to squelch any ground loops....thats if you decide to add a circuit.
    About these irons.An iron is a resistive circuit and will only draw current up to the heat setting its on.It also does this in a linear fashion, rather a smoothcurve without spikes.Unlike a motor circuit which has an inrush at starting and can draw as much as 700 times its running current.

    Thats it for electricity 101 for today class..Be carefull and never test ac with your tongue.
     
  8. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    I would also mention that not only do you want your gear to be on - but if this circuit connects to any other room in the house - you check what is plugged into it. You probably want that draw in the mix as well - depending on what it is though.

    It's amazing how - even if you are in a totally isolated room and can't "hear" a sound (vacum cleaner - fans, etc.)- just what you can pick up through recording gear. 60 cycle motor "sounds" transfer through electrical wires very nicely, as does transformer noise from fluorescent lighting.

    Something else to think about.

    You can probably handle a problem like that with a high quality power conditioner...... it's what i use - and all my gear and additional power strips are "protected" by it.

    I know what you mean about what you see in the construction industry - hell - i've seen old knob and tube wiring in houses with 25 or 30 feet of 18 ga extension cord wire tapped on in the attic and then run down through walls to an outlet or 2 1n a bedroom. Then 6 plug strips from there to handle tv's - hair dryers...... etc......

    Scary though when ya think about it.....

    Happy Hunting

    Rod
     
  9. Scott_Fouts

    Scott_Fouts Guest

    this place is great. thanks for all of the info. i'll keep it all in mind when doing this. looks like i'm going for a Furman AR 1215.

    scott sends . . .
     
  10. Doublehelix

    Doublehelix Distinguished Member

    Joined:
    Oct 7, 2001
    I recently (1 year ago???) added a dedicated 20 amp circuit to my breaker box so that I could run the entire studio off of a dedicated circuit. The earlier comments about ground loop problems are real, and I wanted to avoid any hum or buzz issues. It really didn't cost that much to do the project, although the breaker box is in the basement as is my studio, so it was fairly easy to run the wiring. The entire project took about 20 minutes, cost about $20 in parts, and gave me a lot of piece of mind!

    I personally think it is worth it to know that the circuit is dedicated. The "no refridgerators" comment really got me laughing because before I added the dedicated circuit, I was on the same line as the basement refidge, which I used to turn off during recording sessions... :)

    Also, it is worth it to have everything on ONE circuit...reduces the chance of ground loops.
     
  11. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    Actually - the important thing is to have everything off the same legs of the panel.... you can do multiple circuits off the same hot leg - without going crazy with problems (that go beyond just ground loops).

    Happy Hunting

    Rod
     
  12. JeffreyMajeau

    JeffreyMajeau Active Member

    Joined:
    Sep 5, 2000
    W/V=A My engineer brother told me that that formula's only reliable for DC, but it's worked for me on film shoots where I needed a certain amount of lights and only had so much power.

    I have ONE circuit and ONE outlet in my video edit room. I run the NLE, the amp, the UMatic, the DV deck, the mixer, the office computer, the ceiling fan, printer, analog multitrack, 3 CRT monitors, DAW....

    all at once - I _think_ it's a 20 amp circuit. House was built in 1890, retrofitted with new electrical at some point in the 70s or 80s to accomodate the electric heat (might as well just leave all the gear on, it'd cost about the same :p ).

    Dan
     
  13. Andy Leviss

    Andy Leviss Guest

    Your engineer brother has no idea what he's talking about. That equation is standard for electricity, alternating or not. Changing the direction of the current has no effect on wattage, voltage, or amperage.

    --Andy (who occasionally works as a theatrical electrician)
     
  14. Midlandmorgan

    Midlandmorgan Active Member

    Joined:
    Jul 21, 2002
    We upgraded to a full 125A dedicated system for the studio buildings...each quad box has its own 20A dedicated line...

    Primary (no pun intended) reason for this was clean headroom...20A is quite a bit, but it still can get eaten up pretty quickly...then add on non-audio things like security lights, air conditioning units (2), alarm system, coffee pots (always in use)... you get the idea...

    Plus, upgrading to at least 2 20A dedicated lines will eliminate system strain when (not if...when) you start adding goodies galore....
     
  15. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    midlandmorgan,

    Good for you.... a dedicated panel is always the ideal..... just remember to seperate the legs from the perspective of - motors - cpmpressors - ect. off leg 1 - sound gear off leg 2 - this way you minimize the chances of picking up 60 cycle motor noise on your sound gear.

    Just for the record by the way - Andy Leviss is correct - the formular you're quoting is actually based on "OHMS LAW".

    It applies to any electrical source.

    You can find an explaination for this in UGLY'S Electrical References by George V. Hart, among other places.

    Happy Hunting

    Rod
     
  16. Davedog

    Davedog Distinguished Member

    Joined:
    Dec 10, 2001
    Location:
    Pacific NW
    Everybodys an Electrician!!.......I simply want to second Rod's point about about keeping motor loads off of your delicate electronic equipment circuits.Motors 'spike' when starting and add some real interesting harmonics to their current.These can be easily assimilated by gear on the same circuit and also by signal lines laid in close proximity through walls etc.So watch what youre doing unless the 60hz hum of your airconditioner is your idea of 'The New Music'......Also..flourescent lighting emits frequencies that can be picked up by different pieces of gear.Tube amps love them...Flourescent lights are in Bflat in case you want to use them for something.
     
  17. Rod Gervais

    Rod Gervais Active Member

    Joined:
    Jun 8, 2003
    Location:
    Central Village, CT
    Dave,

    almost eveone is an electrician - those of us who aren't do some electrical engineering. :D

    A subtle difference - but a difference none the less....... :p:


    Happy Hunting

    Rod
     
  18. sdevino

    sdevino Active Member

    Joined:
    Mar 31, 2002
    Chiming in as another EE, in the US I use the following rules:

    Allow 1 amp for every 100W of power.
    Since i (current) = P/E (power/Voltage)
    Since line voltage varies between 110 and 120 v, the formula above will give you a 10 to 17% safety factor.

    So add up the power consumption from the labels next tot he plug on all your gear, divide by 100 and that would be the current required.

    This is a common technique used by theatre lighting techs.

    Steve
     

Share This Page