Why so much talk of 240v?

Discussion in 'DIY' started by Ognennyy, Feb 10, 2011.

  1. Ognennyy

    Ognennyy Begun Flowering

    My working knowledge of electricity is modest. I'm comfortable with gutting/remodeling and rewiring a room, but not an entire house. Can wire 3-way switches, end of the run switches powering multiple lights, all that tricky shit that's a nightmare to a newb, and caused me to rip new sheetrock off to rewire circuits so many years ago when I learned those circuits the hard way lol.


    I see so much talk of 240v in discussions on DIY projects in here and it's raising my eyebrows. The reason for my concern is I'm in the analysis/design phases for an indoor grow setup. So if ya'll know something I don't, please hook me up. I'd love to have all the knowledge I can to avoid some "hindsight is always 20x20" after I poor dollars and hours into this setup.


    I'm only planning to go with 600w lights, but say for argument's sake I were to go with a 1000w HP for flower box and 1000w MH for the veg box. Each 1000w light draws 1000w/120v=8.3 amps. My inclination would be either to wire each one on its own 15amp breaker from the panel, or to run one wire out of a 20amp breaker, then split the line at a junction, and feed each light from the junction box.


    What am I missing that I don't see the necessity for 200v here?
     
  2. RKinG

    RKinG Full Flowering

    Fairly certain that some members are from Europe as well, 240v is the norm there.
     
  3. JuggaloKing420

    JuggaloKing420 Just clownin around

    If your working with multiple lights(more than 2k's worth) 240v runs less total amps..I ran a 50amp sub panel into my room with 30 amps 120v and 20 amps 240v.. The 240v is for just lights.. Instead of needing roughly 30 amps for 3k 120v I can now run 3k 240v off a 20 amp breaker, leaving the extra amperage for other shit. You're really only going to need 240v if you need more amps..


    Its early and I have to get the kid out of the bath and off to school.. Hope this helped.
     
  4. Green Goblin

    Green Goblin Cannabis Connoisseur

    U dont wanna draw more than 80% of ur breaker rating. 16 amps on a 20 amp circuit is not good...go with a 30amp breaker and appropriaye wire size in that scenario.


    16amp max on a 20


    24amps max on a 30


    :pimp:
     
  5. JuggaloKing420

    JuggaloKing420 Just clownin around

    So which one is it, GG? 16 amps on a 20 good or bad? Your post is kind of contradictory..


    My F-I-L is a licensed electrician and that's the setup he told me to go for.
     
  6. Green Goblin

    Green Goblin Cannabis Connoisseur

    You make it confusing.,16 amps is the,max for a 20 amp breaker. 8.3 + 8.3 is 16.6


    If you were drawing 16 on a 20 you may end up with a hot breaker. Therefor 16 on a 20 is not good.


    Am I talkin fuckin greek?
     
  7. rasganjah

    rasganjah True Ganjaman

    Look the advantage of 240V over 120V is a lower amperage draw per light or appliance. A 1k watt light on a 240V circuit pulls approx 4.16 amps draw. So if you are wired for 240V power you can run more lights per circuit safely. I run all 5k watt of HPS lighting in my room on a single 30AMP 240V circuit. It's simply more efficient. When you are running several high wattage lights, appliances etc. it's more efficient to use 240V circuits. Some extremely high wattage shop type equipment draws so much wattage that they are only setup to run on 240V safely. If they were to run on 120V it would be too high of an amperage load.
     
  8. JuggaloKing420

    JuggaloKing420 Just clownin around

    Ognn - I'm not trying to start shit in your thread.. 240v = more lights, less amps
     
  9. mt.king

    mt.king mud drags champion

    I'll break it to you so everybody can be happy


    Less amps less heat Less heat less resistance Less resistance less heat all in all


    It means less power consumption and wear on all electronic components plugins wires breakers ect.
     
    rasganjah likes this.
  10. rasganjah

    rasganjah True Ganjaman

    Si senor, es correcto!
     
  11. Ognennyy

    Ognennyy Begun Flowering

    Yeah that sounds pretty close to what I came up with as well. I play poker on Thursdays with guys who all do electrical contracting together. They said the main reason people do that is because when you split the load in half, onto two poles in the device, there is less resistance. Ballasts will last longer apparently.


    Haha the one answer I got most up above, and knew to be incorrect before I asked the question, is "less total amps". 20amps is 20amps is 20amps. Doesn't matter if you send it down one conductor, or split it and send 10amps down two conductors, 10x2=20amps. Anyway you slice it up.


    If you're running, let's say a 1,000W HPS and 1,000W MH, for a total of 2,000W, and doing so for 20 hours a day. You find your power consumption by (watts x number of hours of usage) / 1000. So in our case, (2000 x 20) / 1000 = 40kWh, which in my area where electricty runs about $.06 per kWh, means it costs $2.40 / day to run those lights. Power company doesn't care if I send all those watts down one conductor, two conductors, one hundred conductors... (and in fact, it is abstracted from them. they can't figure that out even if they want to, without coming here) it's gonna cost $2.40 / day no matter how you wire it. Same # of amps, same # of watts.
     
  12. rasganjah

    rasganjah True Ganjaman

    Amps X Volts = Watts Once I learned that it all made sense when figuring amperage draws.
     
  13. Ognennyy

    Ognennyy Begun Flowering

    NO! It's Watts / Volts = Amps! Hehe j/k :p
     
  14. Chronic Don

    Chronic Don Daddy of RP & GG

    so if its 240v or 120v they still take the same amount of watts per hr, a 1000w drawn at 120v and 1000w drawn at 240v is still 1 kilowatt of power. either volt you still use the same amount of electricity you pay for.


    think of it all as water flow, volts as the size of pipe, amps as the pressure and watts as the total that comes out the end. its more work to push 1000w out of a small pipe er volt then it is out of a larger pipe er volt so then the more work the more heat the more heat the more losses.
     
  15. Useless

    Useless Diogenes Reincarnate

    At 120 VAC a 1kw HPS draws 10.3-10.5 amps when firing up, after it is warm is drops to between 9.8 and 9.3 amps depending on how "clean" your incoming voltage is.


    Aside from using 1/2 of the amperage than 120V, because 240v runs through 2 legs (phases) it also makes the ballast run slightly more efficient.


    Chronic Don - you almost got the analogy right. Voltage would be the equivalent of the water pressure, and amperage the volume of water. Least that's how my old college Professors and Engineering co-workers always refer to it. ;)
     
  16. Chronic Don

    Chronic Don Daddy of RP & GG

    I am not sure about that, watts is the product/volume not amps as you dont pay for amperage you pay for watts used or kilowatts used. it was explained to me as volt is the size of the pipe, times the pressure in the pipe or amperage going thru the pipe/voltage is equal to the amount of product moved or watts.


    in any event as Ofo says it will save you money on wire, and on connections/equipment and on cooling etc plus will cause less heat in the wires. however if a newbie is not comfortable with the concept of using 240v then maybe its best they use extra equipment and go 120v
     
  17. teamster6

    teamster6 Guest

    I run two lights on 240v and also two lights on 120v. The 240v is just a tad cheaper but hardly worth mentioning as far as the electric bill. I only do this because I had the 240v outlets already in and it does not overload all the circuits with everything else I have running in the room.


    t6
     
  18. rasganjah

    rasganjah True Ganjaman

    I use 240V for my 8k watt grow simply because it's more efficient, all the way around. Less wire, less breakers, less resistance. It's a simple analogy to think of it as 120V is a single lane road. Only so much traffic can pass, but on a 240V circuit it's like a 2 lane expressway, now twice as much traffic can pass in the same amount of time. Less resistance.
     
  19. SteelCity Smoker

    SteelCity Smoker To Be Continued

    I am cracking up with all the analogies. So here is my 2 cents.


    Voltage is a measurement of EMF or ElectroMotive Force. EMF is what pushes the current and in turn the current measured in amperes "does the work". Cars run on a 12v system and if you look at the devices that run on 12v they are current based devices they draw more current because EMF is at a premium with only 12v pushing. An average alternator is 75-110amps that's as much as a house just for some lights, ignition and the radio etc. When there is more EMF available it's easier to get the job done with less current. When you are doing things like charging up large capacitors it's better to be faster than stronger since it acts as a buffer regardless...Steelcity
     
  20. Ognennyy

    Ognennyy Begun Flowering

    Two 20amp single pole breakers = two slots in the panel


    One 40amp *double pole* breaker = two slots in the panel


    Does one 40amp double pole breaker cost less than two 20amp single poles? That'd be another wonderful reason (along with 3 conductor wire not costing twice as much as 2 conductor wire, of the same gauge) for 220. Would be another great money saver.


    All in all thanks for great info everyone. This post has done exactly what I was hoping for, and that's show me a lot of points of view I'd never seen before.
     

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