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How many computers can i plug into one power outlet?

Discussion in 'Electronics & Electrics' started by ChEEkY ChiNo, Jun 1, 2003.

  1. Gnuthad

    Gnuthad Member

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    That would be 2.5 for power, but not all electricians run this, some I've seen have run the slightly cheaper 1.5 for power.

    Not all houses have circuit breakers, and those that use fuses can usually be upgraded to breakers from pretty much any hardware store etc. Such add-in breakers come in 8A, 16A, 20A and 32A, all the same physical size. There is nothing stopping someone from plugging in a 32A breaker on their lights because they've got a few hundred downlights installed.

    Yes, I think this is the case, but I'd sure like to be able to pull through just a few more amps. My power is underground so running 3-phase isn't really a viable option, not when the conduit needs to be dug up and then replaced.
     
  2. Outlore

    Outlore Member

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    i remember a lan a few years ago, in a mates back room, it was the largest lan we had ever had, 16 poeple, with room for 10 :p

    now, his room and the back room of his house are all on the same circuit, allong with the kitchen and laundry (it was a budget extension before the bought the place). now with 16 comps running, him mum decided to to a load of washing... and when that was done, she decided to do another load, and put the first one in the drier. ran fine. it was when the went to cook some food in the microwave that it went downhill... and that was a 15amp fuse...

    i myself have run 18 player lans, all on the one 15A line, and havent had a problem. it's been spread out over 6 seperate sockets, but still the one breaker...

    if you were running a public lan, then worry about power. but if you're just at home, have as many people as you want, cos i could almost gaurintee that you'll run out of table space and chairs before you start tripping breakers/fuses
     
  3. Aaron_85

    Aaron_85 Member

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    2.5 isnt much more than 1.5... especialy if you get it at wholesale like most elictricians do i think its $70 for a roll of 2.5 and $50 for 1.5 (100m))... but i spose if they wanna pinch pennies here and there

    yeah, i geuss so. but i reckon it would probly work out cheaper if you replaced all your fuses with circut breakers and get proper ones installed by an electrician. the plug in ones are like 100 bucks each, while normal ones are like 15 bucks.

    yeah, it would be hard and expensive to get 3 phase in if youve got underground, but it can be done (ive had to do it. 16mm2 3-phase cable is hard as hell to pull thru 50m conduit as the cable is about an inch thick) what you could do to get an extra 63 amps is get annother phase put in. i know that when we do undergrounds we use conduit big enough to allow for annother phase later on (basicly adding annothr wire)
     
  4. Symon

    Symon Castigat ridendo mores

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    That has to be one of the worst things they could have put in the 2000 edition of AS3000. As per the 1991 (and older) standards the minimum size for GPO's was 2.5 sq mm, but now it is up to what the electrical contractor "thinks" is safe. Which is a load of BS if you ask me.

    IMO any electrician who wires outlets in 1.5 sq mm should have their licence suspended. Just my 2c.

    I would be pretty worried if you manage to draw over 63A, you would need a mean A/C or a pretty savage folding farm to achieve that. Either way, you need to consult your supply authority about 3-phase supply, from experience they usually aren't too keen on doing it if you are on a fairly old estate.
     
  5. Gnuthad

    Gnuthad Member

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    Never underestimate the ability of anyone to cut corners in order to save 5c :)
    Not all my house was wired well, my hot water uses a 20A main switch....for an 18A heater. Real safe that is! I'm having a disconnect/reconnect licensed electrician come out in a week or so to replace the switch for a 30A or higher unit and to hook up my new 15A circuit for my computers. (Yes, I really DO need it)
     
  6. Symon

    Symon Castigat ridendo mores

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    Isn't that the truth, I especially hate it when they buy crap circuit breakers that are a whopping 12c cheaper than ones that are half decent - really says a lot for safety. That goes for the RCD units as well.

    When I ran power out to my shed (hey, every man needs a shed doesn't he?) I spent just that little bit more to put decent stuff in there, I can sleep that bit better at night now...
     
  7. PNut

    PNut Member

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    I'm currently in a similar boggled situation. I'm looking at running a 80 person lan at an RSL club function room, which is fairly large with your standard 10amp powerpoints absolutely all over the place, and a single 20amp out the front.
    I'm pretty sure the 20amp should be on its own CB, but with the rest of the standard 10amps, i've got no idea which ones are on the same or separate circuits. Anyone got any ideas on how I can find out if they're on the same circuit or not? I want to avoid having 80 people in total darkness at all costs. :p Getting access to the power switch board at an RSL club isn't exactly possible without cutting through zillions of red tape either. :(
     
  8. D F

    D F Member

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    I have 2 tricks up my sleeve if you want to test if 2 power points are on the same circuit:

    1. Measure for any potential between the 2 respective active lines of each power points to which you are testing. If you measure 415 volts AC, they are on different circuits. (a negative result is still unknown because you can have 2 circuits on the same phase; remember.)
    2. Get a blowheater, plug it in to either of the 2 power points you wish to test. Measure voltage on other receptacle while your friend switches blowheater on and off. Make sure the blowheater you get is 2400watts, the results will be more pronounced.

    You should see a voltage drop of around 5 volts or more. This indicates that the 2 power points in on the same circuit, If it holds steady, its not. Make a map on paper of all the power points, Go round and start testing them all in a systematic order. Mark the ones off as 'like' or unlike. Then, when you have found all the power points on the one circuit, goto another power point that you haven't got a positive result and start again. Typically, you will not have 2 power points on the same circuit being on opposite sides of the room. Also, look to see if you can get access to the kitchen, there is usually 15amp dedicated outlets for cooking appliances, like food heaters etc which you will probably not be using. Also, if you're testing points right next to the distroboard, be aware that the voltage drop you are looking for will be very small, probably less than that of the fluctuation of the normal line voltage.

    And then the circuits could be 16 amps each, so observe the 80% rule again and aim for 10 amps/ circuit. AND USE DOUBLE ADAPTERS to split off some of the computers - split it up 60/40 or 70/30 so you ensure the breakers will not trip in the power boards under normal operation, or even 80/20, if you like. Unlike some lans ccgl cough cough, where the person at the end would merely keep resetting the power board before I could summon some more extension leads, since they didn't have double adapters.. (they were running 11-12/extension power board, and on most runs, I can describe "gentle heating" --even with a 40m run of 1mm^2 copper-- of the extension cords, rather than the significant softening which you will experience at 10.0 amps. (at 20deg ambient).) The problem is that the breakers on those cheap power boards are not very precise, they are simply thermal breakers, the the ampbient temperature can affect their trip point. I had one trip with only 8-9 amps of current at home because of the prolonged consistent heating my blow heater caused it to trip. They are a nuisance more than anything else.

    However, if the recepticles are marked, then you have no problem.

    And a question: whats the physical difference between a 15amp plug and socket, and a 10 amp plug and socket? from what I can tell, the prongs of a 15 and 10 amp plug are the same (besides earth.. ), so is the difference in the power point?
     
    Last edited: Jun 3, 2003
  9. Symon

    Symon Castigat ridendo mores

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    Don't use double adaptors. If it starts a fire, forget about insurance, that's the last thing I'm going to say on that topic.

    The difference between 15A and 10A is in the outlet. A 15A outlet has wider and longer contacts. The pins on the plug are the same (apart from a wider earth pin) but the contacts inside the outlet are larger.

    The 20A outlet will definately be on it's own circuit. Usually (and I mean usually, not always) you would have no more than about 30 points per circuit (a double power point counts as two). Most power circuits are protected by 16 or 20A breakers. So if you use D F's methods for working out what is on what circuit, you should be able to work out how many PC's you can stick on each circuit.

    To LEGALLY use the 20A outlet to full capacity you will need the help of a friendly electrician.
     
  10. Aaron_85

    Aaron_85 Member

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    id like to continue on with a few things i enquired about today.

    we rate 2.5mm at 25A for lenths under 30m (most houses) and over 30 - 100 we do 20A. anything over 100 we do 4mm (and then the voltage drop can still be too much.)

    a 100m roll of 2.5 costs my boss 45 bucks (he is a wholesaler also so he gets it cheap) compared to 100m of 1.5 costs 40 bucks. neglible diff if u ask me. thats also the reason why we run 1.5 for lights, unlike most electricians only use one. 1mm is about 35 bucks a 100m roll, but u can only put round 15 lights to a circut, which is bugger all when u start putting on fans, compared to 20-25 for 1.5 (and the fact that 1mm is i solid core and 1.5 is multcore so its easier to work with.)

    rcd's (safety switch) wont stop you gettign electricuted/dieing. an RCD will only protect you from an active-earth electrocution. an active-neutral connection (of you) the RCD will do shit, and with an active-nuetral short you will get more current flowing through you also. also, youl find that you still can get electrocuted from and active-earth electrocution even with an RCD, and it wont trip, as most of the time your reflexes pull you off before the RCD has a chance to go off. RCD's are really ony usefell if you get latched on to something, or an active shorts out onto the metal casing of an appliance, making it live.

    RCD's are still no substitution for safety and common sense

    a 20A breaker for an 18 amp appliance is excelent. the closer you can get the breaker to the load rating the better. the only problem that you would have there if it was a motor or whatever, as the startup currnet may trip it. but even then you have "d" class circut breakers for motors (normal breakers ar "c" class) which accounts for that allready anyway. just remember -> circut breakers are designed to protect the wiring - NOT the appliance. so its plenty safe as long as the breaker rating is between the appliance rating and the rating of the cable (closer to the appliance rating the better) (after the cable has been der-rated of course)
     
  11. Gnuthad

    Gnuthad Member

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    Please re-read the quoted section of my post. I stated that my HWS had a main switch with a 20A rating....for a unit with an 18A draw. Whilst such a switch would work, it is hardly the safest thing to do, especially with a HWS's normal operating time of 5-6 hours continuous. The breaker is a 20A breaker, a unit which replaces the ceramic fuse unit (my house is 14yrs old)

    Should the HWS ever be upgraded to a larger unit, the main switch (off-peak) will also need to be replaced, merely because some electrician fool couldn't be bothered paying $2 more for a 25A or 30A switch.
     
  12. MacroP

    MacroP Member

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    At least here WA our regulatory authority had the decency to over-ride this decision. It opens the way for some people to be even more 'dodgy'.
     
    Last edited: Jun 6, 2003
  13. MacroP

    MacroP Member

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    I can't see why there should be any red tape. Have you asked them? If they are going to hire the function room out to you, surely they'll let you sort out the power requirements first.
    Maybe they could get it sorted for you. Are the GPO's marked already perhaps? Ask them about RCD protection?

    There's really no easy way to decipher the circuits without access to the switchboard.
     
    Last edited: Jun 6, 2003
  14. PNut

    PNut Member

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    Yes unfortunately there is plenty of red tape, since it's a big RSL club they're not very keen to have the general public have access to their switch boards which also power absolutely everything in the club including their pokies which to them mean thousands if not millions of dollars worth of income. Anything like that would have to go through a board of directors yada yada... and yes... big pain in the buttox... :(
     
  15. Gnuthad

    Gnuthad Member

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    Have you made them aware (preferably in writing) of your intended use of their facilities? Is so, I would be asking them to provide details as to the separate circuits available or risk having them constantly have to reset circuit breakers.

    You will find that a lot of larger premises such as clubs will be able to clearly notify you as to which outlets are on which circuits and often, the outlets themselves will have an indication stuck on them as to which breaker controls their power.
     
    Last edited: Jun 6, 2003
  16. pOpArOb

    pOpArOb Member

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    how many computers u recon I could run in my lil trailer at the local trailor park ??
     
  17. Aaron_85

    Aaron_85 Member

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    OK, so what i gather from this is that there is a 20A SWITCH for the hotwater system aswell as a 20A CIRCUT BREAKER? if thats the case yes the switch for it coulda been bigger. BUT all the places ive dun so far just have the circut breaker on the HWS, thats why i assumed it was jsut a 20A breaker.
     
  18. Gnuthad

    Gnuthad Member

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    Oh, my apologies. I have Off-Peak hot water which requires a separate switch. The rest of the off-peak on the switchboard is installed well, 40A relay, 4mm cable and then they go and do a damn stupid thing like dropping a 20A switch on the circuit.
     
  19. Aaron_85

    Aaron_85 Member

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    ok, i understand now ;)
     
  20. Symon

    Symon Castigat ridendo mores

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    Depends on what you have your trailer plugged into. Most of them have 32A outlets don't they?
     

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