how many watts on one outlet?

Discussion in 'Grow Room Design & Setup' started by basement nirvana, Mar 13, 2010.

  1.  
    Drr

    Drr Well-Known Member


    this guy is bang on..

    the formula is Power(watts) = Volts x Amps
    actually P(w)=E(v) x I(a)...

    watts, amps, volts.. are the units of measurement..

    so we know our volts 120... we know our amps 20 or 15 on a lower case scenerio but we're gonna go with 20..

    P=120x20

    P=2400 watts on that circuit.. BUT

    you wanna use 80% of it(some say 85%).. that's how IAm5toned arrives at the 1920 watts constant over a 20 AMP circuit... If you wanna stay safe and have piece of mind.. BUT also that's why we invented breakers.. they are designed to trip if overused... Just hope your breaker works right.. :bigjoint:

    Just thought i'd give a crash course on how to figure it out... and how he ended up with those numbers... it's the same thing for any volts or amps.. just punch in the numbers.. and you will get the max wattage.. then you multiply by .80 to get the 80% safe use number...

    It's a cake walk once you know the formula..

    ANYWAY... those lights are 1000w X 2... if they are efeicent electronic ballasts then they probly use no more then 1100 watts each.. so 2200 watts total on a high.. (2100 in a best case scenerio) so regardless you're over your safety net BUT under your max.. you don't have much room for spikes.. which will trip the breaker and fuck your light cycle.. not worth finding out..

    Like mentioned above the breaker will heat up over time.. it may not trip with those numbers BUT it will wear out and It may not work right over time.. WHICH is a safety concern...

    You could get away with it ...BUT it is not recommended and YOU'RE responsible for your actions..

    The best thing to do here is run a second 20 amp 120 volt line.. and if your gonna do that, your better off putting in a 30amp 240 volt like mentioned by someone in this thread.. that's if you have room in the breaker... if not another 20 amp will be fine..
  2.  
    IAm5toned

    IAm5toned Well-Known Member

    well the way it works is for any equipment that is to be energized for a period greater than 6 hours shall be rated @ 120% of the maximum ampacity... 6 hours or greater of operation is considered a continuous duty cycle, so this is done to protect the thermal element inside the breaker/fuse. not only can it cause premature tripping or nuiscance tripping, but it can also fuse/weld the breaker shut and cause a failure to trip in a short circuit condition., if you run it @ its maximum rated load with a continuous duty cycle, especially over extended periods of time. the danger is not on the first run, but maybe on the 5th.... by rating your breakers @ 80%, you prevent that.
    with a 100 amp breaker, just because the numbers are simple to demonstrate-

    100 amp breaker = 100% load = 100 amp

    80% load = 80 amps.

    80 amps x 120% = 100 amps

    you can see you the 120% works now. by rating your breakers @ 80%, your rating your equipment for 120% ampacity, as required by code ;)
    multiplying the max amperage by .8 on a breaker, gives you the exact number of amps you can safely run. or watts. the equation works either way. i always use amps myself just because thats just easier for me, ive been doing it long enough i tend to have all the wattages memorized anyway...

    so to size a breaker for a grow op- multiply the max wattage of all connected equipment by 120%. then convert the wattage into amperage by dividing by the voltage.

    heres an example: (im ust inventing the wattages, bear with me if there not dead on)

    3 600 hid lights. max input power = 660w per ballast.
    2 fans 45w each
    2 pumps, 75w each
    timer/contacter 20w

    660 x 3
    45 x 2
    75 x 2
    + 20
    2240w
    x 120%
    2688w

    2688w/240v= 11.2 amps @ 240v. you always round up to the nearest size so for our examples sake it would be a 15 amp breaker.

    to find what you can run on an existing breaker-

    multiply the amperage by the voltage by 80%

    20 amp breaker, @ 120v... how many lamps can i run on it??

    20 x 120 x 80% = 1920w of lighting goodness for your baby girls.

    1920w x 120% = 19.2 (always round up, remember?? so its 20 amps.)

    and thats how it works. for any power equation.
  3.  
    imlegal

    imlegal Active Member

    ihave a 400w hps, a floor fan, and a small humidifier plugged to a bathroom outlet u think im maxin it out at all? thanks for any help because last thing i want to do is create a fire
  4.  
    sixstring2112

    sixstring2112 Active Member

    you should be fine. a good hair dryer will pull 1200 - 1500 watts and your under that. nothing like takin a dump under the street lights:o
  5.  
    WaRpIg

    WaRpIg Well-Known Member

    Dont use 14 gauage wires use 12 or 10 cuz the big number mean smaller wires ...:) i would use those outlet that have own breaker just in case ....so u have 2 breaker :)
  6.  
    JeffersonBud

    JeffersonBud Active Member

    Its not necessarily about the watts, its more about amps. Usually 100 watts is around an amp. Most plugs in the house are rated for 15-20 amps @120 volts. There is sometimes an initial amp increase when starting a device as well. 30 amp lines are 240 volts and are usually connected to large appliances such as the oven or HVAC. If you have the option to run your ballasts off of a 240v plug, then do it! contrary to popular belief, you won't really save any money, but you will cut your devices amp usage by half. if 1 1000watt ballast runs @ 10 amps on 120v, then it can run only 5 amps on 240v. This allows more lights to run on a single breaker.
    Most of your products have amp rating and this is what you want to look for.
  7.  
    WaRpIg

    WaRpIg Well-Known Member

    Its not necessarily about the watts, its more about amps. Usually 100 watts is around an amp. Most plugs in the house are rated for 15-20 amps @120 volts. There is sometimes an initial amp increase when starting a device as well. 30 amp lines are 240 volts and are usually connected to large appliances such as the oven or HVAC. If you have the option to run your ballasts off of a 240v plug, then do it! contrary to popular belief, you won't really save any money, but you will cut your devices amp usage by half. if 1 1000watt ballast runs @ 10 amps on 120v, then it can run only 5 amps on 240v. This allows more lights to run on a single breaker.
    Most of your products have amp rating and this is what you want to look for.


    so i can run 1 1000 watts on 120v outlet with a single 20 amp breaker will be ok ?
  8.  
    JeffersonBud

    JeffersonBud Active Member

    so i can run 1 1000 watts on 120v outlet with a single 20 amp breaker will be ok ?[/QUOTE]

    Yes you can. It will most likely consume 10 amps. Just make sure that your romex wire (12 gauge) on the plug and the breaker is made for 20 amps. 20 amp plugs look like this...

    http://www.frentzandsons.com/Hardware References/plugandreceptacleconfiguratio.htm

    As you can see, the plugs on a 15 amp are the normal small (hot) large(neutral) and ground. The 20 amp has an extra horizontal plug space on it. Usually the plugs are rated for 15 amp even though they are using the 12 guage romex because not many people run things larger then15 amps that on a single plug. You can get away with the normal plug if you are only running 10 amps or one single light but I like to make sure everything is up to the full 20 amp spec.

    Hopefully im not just rambling about things you already know :)
  9.  
    JeffersonBud

    JeffersonBud Active Member

    also, you can run the regular male plugs on the 20 amp. They have the extra horizontal plug not only to distinguish it from the 15 amp, but so they can accept more devices.
  10.  
    WaRpIg

    WaRpIg Well-Known Member

    the 1000 watts light power supply have 2 opt. 120 v or 240 . it had that reg plugs like house .. is it ok use that plugs or should i change it to one link u shouw me ? i only run 120 v out that power supply the 240 kinda too much for me ..
  11.  
    WaRpIg

    WaRpIg Well-Known Member

    Should i change amp to 10 to be safe or is it safe with 20 amp breaker ?
  12.  
    JeffersonBud

    JeffersonBud Active Member

    Yes, you should be fine with the plugs you have. you want to keep the 20 amp breaker. The larger amp rating on the breaker, the better. The smaller number gauge wire, the better. Are you running anything else on the circuit (all the plugs that run into the 20 amp breaker) like pumps, fans, ect?
  13.  
    IAm5toned

    IAm5toned Well-Known Member

    in all seriousness, its never about guessing! electricity is all about math, because math deals in absolutes. when dealing with electricity, dont guess. either know before you start or consult a pro. a little research can go a long way and save you thousands in the long run. a 1000w fixture does not pull 10 amps, for instance. if it did, id be worried about that ballast catching on fire.
    this thread is the reason I donate my time here. call it community service for karma.

    look, and listen, ok?

    any HID lamp requires a ballast. the ballasts power factor will tell you what wattage it pulls in addition to the lamp. thats right, a ballast also consumes electrical energy. you multiply the power factor by the lamp wattage to get the maximum input power. sometimes the ballast manufacturer is nice and on the nameplate rating of theballast they will put the maximum input power. this is what the ballast lamp combo consumes. sometimes it is in amps,and sometimes it is in watts. sometimes its not there at all, and all there is is an efficincy rating/power factor.

    for examples sake, lets pretend the maximum input power of your light fixture is 1075 watts.

    1075w @ 120vac = 8.96 amps
    8.96 amps @ 120vac x 120% (continuous duty cycle demand factor) = 10.76 amps.
    1075w @ 240vac = 4.48 amps
    4.48 amps @ 240vac x 120% (continuous duty cycle demand factor) = 5.38 amps

    note how the wattage never changes in relation to the voltage, but the amperage is inversely proportionate to the voltage. the higher the voltage, the lower the amperage. the lower the voltage, the higher the amperage.......

    someoone said in a previous post a 30 amp breaker is 240v. this is horse shit. the amperage of a breaker has absolutley nothing to do with the voltage of the circuit. the voltage of the circuit is determined by the availability of power from a transformer/generator. 99% of all households in the US have 120/240v single phase service. that means in order to have 240v, you must use both phases of the a/c power cycle. in plain english, that means a 240v breaker takes up 2slots in a panel. do not be fooled by a tandem breaker, also called a piggyback breaker. a tandem breaker fits 2 circuits in one slot of the of the panel, they are easily identified by there smaller size compared to other breakers. a 240v breaker will also have a bar, or common trip that locks both handles together so that if one phase trips, it also trips the other.

    school is now out of session.

    thank you, come again
  14.  
    JeffersonBud

    JeffersonBud Active Member

    Thanks for the clarification. I did not mean to state that all 30 amp breakers are 240v. Most of the time, household appliances are on a 30 amp double pole breaker, but as stated, a rating of amperage on a breaker does not mean its 240 volt.
  15.  
    WaRpIg

    WaRpIg Well-Known Member

    I run many wires to once place like blower have own breaker and light have own breaker ...
  16.  
    robbie4door

    robbie4door Member

    now where u plug the cord into the receptical. the plug and the cord/cord end have to be sized also???????
  17.  
    IAm5toned

    IAm5toned Well-Known Member

    yes, they do. however a plug that is SPEC Grade can be run @ 100% ampacity. so a 20 amp SPEC grade plug is good for 20 amps. as long as it is terminated correctly.
    dont use anything but SPEC grade plugs for a grow op. they are the most expensive, but they are built for heavy duty usage, as compared to a regular .99 plug from the bargain bin isnt good for 80% of the amperage on the packaging...
    cord ends need to be rated @ 120% however. that id critical. the cord end is the connection point, and is what we like to call a point of failure in the trade. this means the probability of something going wrong there is pretty high, so in order to avoid problems, dont cut corners. do it right, and sleep at night... as ive told many apprentices.
  18.  
    JeffersonBud

    JeffersonBud Active Member

  19.  
    robbie4door

    robbie4door Member

    thanks bud
    i thought so but just wanted to stress that point of contact is the most croushal
  20.  
    stoney917

    stoney917 Member

    so if my math is correct. i have a 20a breaker with 14 wire ran to it. i plan on runnin a 1000w hps with 2 136w fans and 2 20w airpumps bringin me to 1312w so lets say round up 1400w total now my math tells me max load would be 1800w. is this correct? 15x120=1800 and i know you should not max it out and cannot change ne of the wiring easily.i think i remember hearing 1440 continous so im stiil below max recomendations.

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